# vmalert

`vmalert` executes a list of the given [alerting](https://prometheus.io/docs/prometheus/latest/configuration/alerting_rules/)
or [recording](https://prometheus.io/docs/prometheus/latest/configuration/recording_rules/)
rules against configured `-datasource.url` compatible with Prometheus HTTP API. For sending alerting notifications
vmalert relies on [Alertmanager](https://github.com/prometheus/alertmanager) configured via `-notifier.url` flag.
Recording rules results are persisted via [remote write](https://prometheus.io/docs/prometheus/latest/storage/#remote-storage-integrations)
protocol and require `-remoteWrite.url` to be configured.
Vmalert is heavily inspired by [Prometheus](https://prometheus.io/docs/alerting/latest/overview/)
implementation and aims to be compatible with its syntax.

A [single-node](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html#vmalert)
or [cluster version](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html#vmalert)
of VictoriaMetrics are capable of proxying requests to vmalert via `-vmalert.proxyURL` command-line flag. 
Use this feature for the following cases:
* for proxying requests from [Grafana Alerting UI](https://grafana.com/docs/grafana/latest/alerting/);
* for accessing vmalerts UI through VictoriaMetrics Web interface.

## Features

* Integration with [VictoriaMetrics](https://github.com/VictoriaMetrics/VictoriaMetrics) TSDB;
* VictoriaMetrics [MetricsQL](https://docs.victoriametrics.com/MetricsQL.html)
  support and expressions validation;
* Prometheus [alerting rules definition format](https://prometheus.io/docs/prometheus/latest/configuration/alerting_rules/#defining-alerting-rules)
  support;
* Integration with [Alertmanager](https://github.com/prometheus/alertmanager) starting from [Alertmanager v0.16.0-alpha](https://github.com/prometheus/alertmanager/releases/tag/v0.16.0-alpha.0);
* Keeps the alerts [state on restarts](#alerts-state-on-restarts);
* Graphite datasource can be used for alerting and recording rules. See [these docs](#graphite);
* Recording and Alerting rules backfilling (aka `replay`). See [these docs](#rules-backfilling);
* Lightweight and without extra dependencies.
* Supports [reusable templates](#reusable-templates) for annotations;
* Load of recording and alerting rules from local filesystem, URL, GCS and S3;
* Detect alerting rules which [don't match any series](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/4039).

## Limitations

* `vmalert` execute queries against remote datasource which has reliability risks because of the network.
  It is recommended to configure alerts thresholds and rules expressions with the understanding that network
  requests may fail;
* by default, rules execution is sequential within one group, but persistence of execution results to remote
  storage is asynchronous. Hence, user shouldn't rely on chaining of recording rules when result of previous
  recording rule is reused in the next one;

## QuickStart

To build `vmalert` from sources:

```console
git clone https://github.com/VictoriaMetrics/VictoriaMetrics
cd VictoriaMetrics
make vmalert
```

The build binary will be placed in `VictoriaMetrics/bin` folder.

To start using `vmalert` you will need the following things:

* list of rules - PromQL/MetricsQL expressions to execute;
* datasource address - reachable endpoint with [Prometheus HTTP API](https://prometheus.io/docs/prometheus/latest/querying/api/#http-api) support for running queries against;
* notifier address [optional] - reachable [Alert Manager](https://github.com/prometheus/alertmanager) instance for processing,
  aggregating alerts, and sending notifications. Please note, notifier address also supports Consul and DNS Service Discovery via
  [config file](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/app/vmalert/notifier/config.go).
* remote write address [optional] - [remote write](https://prometheus.io/docs/prometheus/latest/storage/#remote-storage-integrations)
  compatible storage to persist rules and alerts state info. To persist results to multiple destinations use vmagent
  configured with multiple remote writes as a proxy;
* remote read address [optional] - MetricsQL compatible datasource to restore alerts state from.

Then configure `vmalert` accordingly:

```console
./bin/vmalert -rule=alert.rules \            # Path to the file with rules configuration. Supports wildcard
    -datasource.url=http://localhost:8428 \  # Prometheus HTTP API compatible datasource
    -notifier.url=http://localhost:9093 \    # AlertManager URL (required if alerting rules are used)
    -notifier.url=http://127.0.0.1:9093 \    # AlertManager replica URL
    -remoteWrite.url=http://localhost:8428 \ # Remote write compatible storage to persist rules and alerts state info (required if recording rules are used)
    -remoteRead.url=http://localhost:8428 \  # Prometheus HTTP API compatible datasource to restore alerts state from
    -external.label=cluster=east-1 \         # External label to be applied for each rule
    -external.label=replica=a                # Multiple external labels may be set
```

Note there's a separate `-remoteWrite.url` command-line flag to allow writing results of
alerting/recording rules into a different storage than the initial data that's
queried. This allows using `vmalert` to aggregate data from a short-term,
high-frequency, high-cardinality storage into a long-term storage with
decreased cardinality and a bigger interval between samples.
See also [stream aggregation](https://docs.victoriametrics.com/stream-aggregation.html).

See the full list of configuration flags in [configuration](#configuration) section.

If you run multiple `vmalert` services for the same datastore or AlertManager - do not forget
to specify different `-external.label` command-line flags in order to define which `vmalert` generated rules or alerts.

Configuration for [recording](https://prometheus.io/docs/prometheus/latest/configuration/recording_rules/)
and [alerting](https://prometheus.io/docs/prometheus/latest/configuration/alerting_rules/) rules is very
similar to Prometheus rules and configured using YAML. Configuration examples may be found
in [testdata](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/app/vmalert/config/testdata) folder.
Every `rule` belongs to a `group` and every configuration file may contain arbitrary number of groups:

```yaml
groups:
  [ - <rule_group> ]
```

### Groups

Each group has the following attributes:

```yaml
# The name of the group. Must be unique within a file.
name: <string>

# How often rules in the group are evaluated.
[ interval: <duration> | default = -evaluationInterval flag ]

# Limit the number of alerts an alerting rule and series a recording
# rule can produce. 0 is no limit.
[ limit: <int> | default = 0 ]

# How many rules execute at once within a group. Increasing concurrency may speed
# up round execution speed.
[ concurrency: <integer> | default = 1 ]

# Optional type for expressions inside the rules. Supported values: "graphite" and "prometheus".
# By default "prometheus" type is used.
[ type: <string> ]

# Optional list of HTTP URL parameters
# applied for all rules requests within a group
# For example:
#  params:
#    nocache: ["1"]                # disable caching for vmselect
#    denyPartialResponse: ["true"] # fail if one or more vmstorage nodes returned an error
#    extra_label: ["env=dev"]      # apply additional label filter "env=dev" for all requests
# see more details at https://docs.victoriametrics.com#prometheus-querying-api-enhancements
params:
  [ <string>: [<string>, ...]]

# Optional list of HTTP headers in form `header-name: value`
# applied for all rules requests within a group
# For example:
#  headers:
#    - "CustomHeader: foo"
#    - "CustomHeader2: bar"
# Headers set via this param have priority over headers set via `-datasource.headers` flag.
headers:
  [ <string>, ...]

# Optional list of HTTP headers in form `header-name: value`
# applied for all alert notifications sent to notifiers 
# generated by rules of this group.
# For example:
#  notifier_headers:
#    - "TenantID: foo"
notifier_headers:
        [ <string>, ...]

# Optional list of labels added to every rule within a group.
# It has priority over the external labels.
# Labels are commonly used for adding environment
# or tenant-specific tag.
labels:
  [ <labelname>: <labelvalue> ... ]

rules:
  [ - <rule> ... ]
```

### Rules

Every rule contains `expr` field for [PromQL](https://prometheus.io/docs/prometheus/latest/querying/basics/)
or [MetricsQL](https://docs.victoriametrics.com/MetricsQL.html) expression. `vmalert` will execute the configured
expression and then act according to the Rule type.

There are two types of Rules:

* [alerting](https://prometheus.io/docs/prometheus/latest/configuration/alerting_rules/) -
  Alerting rules allow defining alert conditions via `expr` field and to send notifications to
  [Alertmanager](https://github.com/prometheus/alertmanager) if execution result is not empty.
* [recording](https://prometheus.io/docs/prometheus/latest/configuration/recording_rules/) -
  Recording rules allow defining `expr` which result will be then backfilled to configured
  `-remoteWrite.url`. Recording rules are used to precompute frequently needed or computationally
  expensive expressions and save their result as a new set of time series.

`vmalert` forbids defining duplicates - rules with the same combination of name, expression, and labels
within one group.

#### Alerting rules

The syntax for alerting rule is the following:

```yaml
# The name of the alert. Must be a valid metric name.
alert: <string>

# The expression to evaluate. The expression language depends on the type value.
# By default, PromQL/MetricsQL expression is used. If group.type="graphite", then the expression
# must contain valid Graphite expression.
expr: <string>

# Alerts are considered firing once they have been returned for this long.
# Alerts which have not yet been fired for long enough are considered pending.
# If param is omitted or set to 0 then alerts will be immediately considered
# as firing once they return.
[ for: <duration> | default = 0s ]

# Whether to print debug information into logs.
# Information includes alerts state changes and requests sent to the datasource.
# Please note, that if rule's query params contain sensitive
# information - it will be printed to logs.
# Is applicable to alerting rules only.
# Available starting from https://docs.victoriametrics.com/CHANGELOG.html#v1820
[ debug: <bool> | default = false ]

# Defines the number of rule's updates entries stored in memory
# and available for view on rule's Details page.
# Overrides `rule.updateEntriesLimit` value for this specific rule.
# Available starting from https://docs.victoriametrics.com/CHANGELOG.html#v1860
[ update_entries_limit: <integer> | default 0 ]

# Labels to add or overwrite for each alert.
labels:
  [ <labelname>: <tmpl_string> ]

# Annotations to add to each alert.
annotations:
  [ <labelname>: <tmpl_string> ]
```

#### Templating

It is allowed to use [Go templating](https://golang.org/pkg/text/template/) in annotations to format data, iterate over
or execute expressions.
The following variables are available in templating:

| Variable                           | Description                                                                                               | Example                                                                                                                                                                |
|------------------------------------|-----------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| $value or .Value                   | The current alert's value. Avoid using value in labels, it may cause unexpected issues.                   | {% raw %}Number of connections is {{ $value }}{% endraw %}                                                                                                             |
| $activeAt or .ActiveAt             | The moment of [time](https://pkg.go.dev/time) when alert became active (`pending` or `firing`).           | {% raw %}http://vm-grafana.com/panelId=xx?from={{($activeAt.Add (parseDurationTime \"1h\")).Unix}}&to={{($activeAt.Add (parseDurationTime \"-1h\")).Unix}}{% endraw %} |
| $labels or .Labels                 | The list of labels of the current alert. Use as ".Labels.<label_name>".                                   | {% raw %}Too high number of connections for {{ .Labels.instance }}{% endraw %}                                                                                         |
| $alertID or .AlertID               | The current alert's ID generated by vmalert.                                                              | {% raw %}Link: vmalert/alert?group_id={{.GroupID}}&alert_id={{.AlertID}}{% endraw %}                                                                                   |
| $groupID or .GroupID               | The current alert's group ID generated by vmalert.                                                        | {% raw %}Link: vmalert/alert?group_id={{.GroupID}}&alert_id={{.AlertID}}{% endraw %}                                                                                   |
| $expr or .Expr                     | Alert's expression. Can be used for generating links to Grafana or other systems.                         | {% raw %}/api/v1/query?query={{ $expr&#124;queryEscape }}{% endraw %}                                                                                                  |
| $for or .For                       | Alert's configured for param.                                                                             | {% raw %}Number of connections is too high for more than {{ .For }}{% endraw %}                                                                                        |
| $externalLabels or .ExternalLabels | List of labels configured via `-external.label` command-line flag.                                        | {% raw %}Issues with {{ $labels.instance }} (datacenter-{{ $externalLabels.dc }}){% endraw %}                                                                          |
| $externalURL or .ExternalURL       | URL configured via `-external.url` command-line flag. Used for cases when vmalert is hidden behind proxy. | {% raw %}Visit {{ $externalURL }} for more details{% endraw %}                                                                                                         |

Additionally, `vmalert` provides some extra templating functions listed [here](#template-functions) and [reusable templates](#reusable-templates).

#### Template functions

`vmalert` provides the following template functions, which can be used during [templating](#templating):

- `args arg0 ... argN` - converts the input args into a map with `arg0`, ..., `argN` keys.
- `externalURL` - returns the value of `-external.url` command-line flag.
- `first` - returns the first result from the input query results returned by `query` function.
- `htmlEscape` - escapes special chars in input string, so it can be safely embedded as a plaintext into HTML.
- `humanize` - converts the input number into human-readable format by adding [metric prefixes](https://en.wikipedia.org/wiki/Metric_prefix).
  For example, `100000` is converted into `100K`.
- `humanize1024` - converts the input number into human-readable format with 1024 base.
  For example, `1024` is converted into 1ki`.
- `humanizeDuration` - converts the input number in seconds into human-readable duration.
- `humanizePercentage` - converts the input number to percentage. For example, `0.123` is converted into `12.3%`.
- `humanizeTimestamp` - converts the input unix timestamp into human-readable time.
- `jsonEscape` - JSON-encodes the input string.
- `label name` - returns the value of the label with the given `name` from the input query result.
- `match regex` - matches the input string against the provided `regex`.
- `parseDuration` - parses the input string into duration in seconds. For example, `1h` is parsed into `3600`.
- `parseDurationTime` - parses the input string into [time.Duration](https://pkg.go.dev/time#Duration).
- `pathEscape` - escapes the input string, so it can be safely put inside path part of URL.
- `pathPrefix` - returns the path part of the `-external.url` command-line flag.
- `query` - executes the [MetricsQL](https://docs.victoriametrics.com/MetricsQL.html) query against `-datasource.url` and returns the query result.
  For example, {% raw %}`{{ query "sort_desc(process_resident_memory_bytes)" | first | value }}`{% endraw %} executes the `sort_desc(process_resident_memory_bytes)`
  query at `-datasource.url` and returns the first result.
- `queryEscape` - escapes the input string, so it can be safely put inside [query arg](https://en.wikipedia.org/wiki/Percent-encoding) part of URL.
- `quotesEscape` - escapes the input string, so it can be safely embedded into JSON string.
- `reReplaceAll regex repl` - replaces all the occurrences of the `regex` in input string with the `repl`.
- `safeHtml` - marks the input string as safe to use in HTML context without the need to html-escape it.
- `sortByLabel name` - sorts the input query results by the label with the given `name`.
- `stripDomain` - leaves the first part of the domain. For example, `foo.bar.baz` is converted to `foo`.
  The port part is left in the output string. E.g. `foo.bar:1234` is converted into `foo:1234`.
- `stripPort` - strips `port` part from `host:port` input string.
- `strvalue` - returns the metric name from the input query result.
- `title` - converts the first letters of every input word to uppercase.
- `toLower` - converts all the chars in the input string to lowercase.
- `toTime` - converts the input unix timestamp to [time.Time](https://pkg.go.dev/time#Time).
- `toUpper` - converts all the chars in the input string to uppercase.
- `value` - returns the numeric value from the input query result.

#### Reusable templates

Like in Alertmanager you can define [reusable templates](https://prometheus.io/docs/prometheus/latest/configuration/template_examples/#defining-reusable-templates)
to share same templates across annotations. Just define the templates in a file and
set the path via `-rule.templates` flag.

For example, template `grafana.filter` can be defined as following:

{% raw  %}
```
{{ define "grafana.filter" -}}
  {{- $labels := .arg0 -}}
  {{- range $name, $label := . -}}
    {{- if (ne $name "arg0") -}}
      {{- ( or (index $labels $label) "All" ) | printf "&var-%s=%s" $label -}}
    {{- end -}}
  {{- end -}}
{{- end -}}
```
{% endraw %}

And then used in annotations:

{% raw  %}
```yaml
groups:
  - name: AlertGroupName
    rules:
      - alert: AlertName
        expr: any_metric > 100
        for: 30s
        labels:
          alertname: 'Any metric is too high'
          severity: 'warning'
        annotations:
          dashboard: '{{ $externalURL }}/d/dashboard?orgId=1{{ template "grafana.filter" (args .CommonLabels "account_id" "any_label") }}'
```
{% endraw %}

The `-rule.templates` flag supports wildcards so multiple files with templates can be loaded.
The content of `-rule.templates` can be also [hot reloaded](#hot-config-reload).


#### Recording rules

The syntax for recording rules is following:

```yaml
# The name of the time series to output to. Must be a valid metric name.
record: <string>

# The expression to evaluate. The expression language depends on the type value.
# By default, MetricsQL expression is used. If group.type="graphite", then the expression
# must contain valid Graphite expression.
expr: <string>

# Labels to add or overwrite before storing the result.
labels:
  [ <labelname>: <labelvalue> ]


# Defines the number of rule's updates entries stored in memory
# and available for view on rule's Details page.
# Overrides `rule.updateEntriesLimit` value for this specific rule.
[ update_entries_limit: <integer> | default 0 ]
```

For recording rules to work `-remoteWrite.url` must be specified.

### Alerts state on restarts

`vmalert` has no local storage, so alerts state is stored in the process memory. Hence, after restart of `vmalert`
the process alerts state will be lost. To avoid this situation, `vmalert` should be configured via the following flags:

* `-remoteWrite.url` - URL to VictoriaMetrics (Single) or vminsert (Cluster). `vmalert` will persist alerts state
  into the configured address in the form of time series named `ALERTS` and `ALERTS_FOR_STATE` via remote-write protocol.
  These are regular time series and maybe queried from VM just as any other time series.
  The state is stored to the configured address on every rule evaluation.
* `-remoteRead.url` - URL to VictoriaMetrics (Single) or vmselect (Cluster). `vmalert` will try to restore alerts state
  from configured address by querying time series with name `ALERTS_FOR_STATE`.

Both flags are required for proper state restoration. Restore process may fail if time series are missing
in configured `-remoteRead.url`, weren't updated in the last `1h` (controlled by `-remoteRead.lookback`)
or received state doesn't match current `vmalert` rules configuration.

### Multitenancy

There are the following approaches exist for alerting and recording rules across
[multiple tenants](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html#multitenancy):

* To run a separate `vmalert` instance per each tenant.
  The corresponding tenant must be specified in `-datasource.url` command-line flag
  according to [these docs](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html#url-format).
  For example, `/path/to/vmalert -datasource.url=http://vmselect:8481/select/123/prometheus`
  would run alerts against `AccountID=123`. For recording rules the `-remoteWrite.url` command-line
  flag must contain the url for the specific tenant as well.
  For example, `-remoteWrite.url=http://vminsert:8480/insert/123/prometheus` would write recording
  rules to `AccountID=123`.

* To specify `tenant` parameter per each alerting and recording group if
  [enterprise version of vmalert](https://docs.victoriametrics.com/enterprise.html) is used
  with `-clusterMode` command-line flag. For example:

```yaml
groups:
- name: rules_for_tenant_123
  tenant: "123"
  rules:
    # Rules for accountID=123

- name: rules_for_tenant_456:789
  tenant: "456:789"
  rules:
    # Rules for accountID=456, projectID=789
```

The results of alerting and recording rules contain `vm_account_id` and `vm_project_id` labels
if `-clusterMode` is enabled. These labels can be used during [templating](https://docs.victoriametrics.com/vmalert.html#templating),
and help to identify to which account or project the triggered alert or produced recording belongs.

If `-clusterMode` is enabled, then `-datasource.url`, `-remoteRead.url` and `-remoteWrite.url` must
contain only the hostname without tenant id. For example: `-datasource.url=http://vmselect:8481`.
`vmalert` automatically adds the specified tenant to urls per each recording rule in this case.

If `-clusterMode` is enabled and the `tenant` in a particular group is missing, then the tenant value
is obtained from `-defaultTenant.prometheus` or `-defaultTenant.graphite` depending on the `type` of the group.

The enterprise version of vmalert is available in `vmutils-*-enterprise.tar.gz` files
at [release page](https://github.com/VictoriaMetrics/VictoriaMetrics/releases) and in `*-enterprise`
tags at [Docker Hub](https://hub.docker.com/r/victoriametrics/vmalert/tags).

### Reading rules from object storage

[Enterprise version](https://docs.victoriametrics.com/enterprise.html) of `vmalert` may read alerting and recording rules
from object storage:

- `./bin/vmalert -rule=s3://bucket/dir/alert.rules` would read rules from the given path at S3 bucket
- `./bin/vmalert -rule=gs://bucket/bir/alert.rules` would read rules from the given path at GCS bucket

S3 and GCS paths support only matching by prefix, e.g. `s3://bucket/dir/rule_` matches
all files with prefix `rule_` in the folder `dir`.

The following [command-line flags](#flags) can be used for fine-tuning access to S3 and GCS:

- `-s3.credsFilePath` - path to file with GCS or S3 credentials. Credentials are loaded from default locations if not set.
- `-s3.configFilePath` - path to file with S3 configs. Configs are loaded from default location if not set.
- `-s3.configProfile` - profile name for S3 configs. If no set, the value of the environment variable will be loaded (`AWS_PROFILE` or `AWS_DEFAULT_PROFILE`).
- `-s3.customEndpoint` - custom S3 endpoint for use with S3-compatible storages (e.g. MinIO). S3 is used if not set.
- `-s3.forcePathStyle` - prefixing endpoint with bucket name when set false, true by default.

### Topology examples

The following sections are showing how `vmalert` may be used and configured
for different scenarios.

Please note, not all flags in examples are required:

* `-remoteWrite.url` and `-remoteRead.url` are optional and are needed only if
  you have recording rules or want to store [alerts state](#alerts-state-on-restarts) on `vmalert` restarts;
* `-notifier.url` is optional and is needed only if you have alerting rules.

#### Single-node VictoriaMetrics

The simplest configuration where one single-node VM server is used for
rules execution, storing recording rules results and alerts state.

`vmalert` configuration flags:

```
./bin/vmalert -rule=rules.yml  \                    # Path to the file with rules configuration. Supports wildcard
    -datasource.url=http://victoriametrics:8428 \   # VM-single addr for executing rules expressions
    -remoteWrite.url=http://victoriametrics:8428 \  # VM-single addr to persist alerts state and recording rules results
    -remoteRead.url=http://victoriametrics:8428 \   # VM-single addr for restoring alerts state after restart
    -notifier.url=http://alertmanager:9093          # AlertManager addr to send alerts when they trigger
```

<img alt="vmalert single" width="500" src="vmalert_single.png">

#### Cluster VictoriaMetrics

In [cluster mode](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html)
VictoriaMetrics has separate components for writing and reading path:
`vminsert` and `vmselect` components respectively. `vmselect` is used for executing rules expressions
and `vminsert` is used to persist recording rules results and alerts state.
Cluster mode could have multiple `vminsert` and `vmselect` components.

`vmalert` configuration flags:

```
./bin/vmalert -rule=rules.yml  \                                # Path to the file with rules configuration. Supports wildcard
    -datasource.url=http://vmselect:8481/select/0/prometheus    # vmselect addr for executing rules expressions
    -remoteWrite.url=http://vminsert:8480/insert/0/prometheus   # vminsert addr to persist alerts state and recording rules results
    -remoteRead.url=http://vmselect:8481/select/0/prometheus    # vmselect addr for restoring alerts state after restart
    -notifier.url=http://alertmanager:9093                      # AlertManager addr to send alerts when they trigger
```

<img alt="vmalert cluster" src="vmalert_cluster.png">

In case when you want to spread the load on these components - add balancers before them and configure
`vmalert` with balancer addresses. Please, see more about VM's cluster architecture
[here](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html#architecture-overview).

#### HA vmalert

For HA user can run multiple identically configured `vmalert` instances.
It means all of them will execute the same rules, write state and results to
the same destinations, and send alert notifications to multiple configured
Alertmanagers.

`vmalert` configuration flags:

```
./bin/vmalert -rule=rules.yml \                   # Path to the file with rules configuration. Supports wildcard
    -datasource.url=http://victoriametrics:8428 \   # VM-single addr for executing rules expressions
    -remoteWrite.url=http://victoriametrics:8428 \  # VM-single addr to persist alerts state and recording rules results
    -remoteRead.url=http://victoriametrics:8428 \   # VM-single addr for restoring alerts state after restart
    -notifier.url=http://alertmanager1:9093 \       # Multiple AlertManager addresses to send alerts when they trigger
    -notifier.url=http://alertmanagerN:9093         # The same alert will be sent to all configured notifiers
```

<img alt="vmalert ha" width="800px" src="vmalert_ha.png">

To avoid recording rules results and alerts state duplication in VictoriaMetrics server
don't forget to configure [deduplication](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html#deduplication).
The recommended value for `-dedup.minScrapeInterval` must be greater or equal to vmalert `evaluation_interval`.
If you observe inconsistent or "jumping" values in series produced by vmalert, try disabling `-datasource.queryTimeAlignment`
command line flag. Because of alignment, two or more vmalert HA pairs will produce results with the same timestamps.
But due of backfilling (data delivered to the datasource with some delay) values of such results may differ,
which would affect deduplication logic and result into "jumping" datapoints.

Alertmanager will automatically deduplicate alerts with identical labels, so ensure that
all `vmalert`s are having the same config.

Don't forget to configure [cluster mode](https://prometheus.io/docs/alerting/latest/alertmanager/)
for Alertmanagers for better reliability. List all Alertmanager URLs in vmalert `-notifier.url`
to ensure [high availability](https://github.com/prometheus/alertmanager#high-availability).

This example uses single-node VM server for the sake of simplicity.
Check how to replace it with [cluster VictoriaMetrics](#cluster-victoriametrics) if needed.

#### Downsampling and aggregation via vmalert

_Please note, [stream aggregation](https://docs.victoriametrics.com/stream-aggregation.html) might be more efficient
for cases when downsampling or aggregation need to be applied **before data gets into the TSDB.**_

`vmalert` can't modify existing data. But it can run arbitrary PromQL/MetricsQL queries
via [recording rules](#recording-rules) and backfill results to the configured `-remoteWrite.url`.
This ability allows to aggregate data. For example, the following rule will calculate the average value for
metric `http_requests` on the `5m` interval:

```yaml
  - record: http_requests:avg5m
    expr: avg_over_time(http_requests[5m])
```

Every time this rule will be evaluated, `vmalert` will backfill its results as a new time series `http_requests:avg5m`
to the configured `-remoteWrite.url`.

`vmalert` executes rules with specified interval (configured via flag `-evaluationInterval`
or as [group's](#groups) `interval` param). The interval helps to control "resolution" of the produced series.
This ability allows to downsample data. For example, the following config will execute the rule only once every `5m`:

```yaml
groups:
  - name: my_group
    interval: 5m
    rules:
    - record: http_requests:avg5m
      expr: avg_over_time(http_requests[5m])
```

Ability of `vmalert` to be configured with different `-datasource.url` and `-remoteWrite.url` command-line flags
allows reading data from one data source and backfilling results to another. This helps to build a system
for aggregating and downsampling the data.

The following example shows how to build a topology where `vmalert` will process data from one cluster
and write results into another. Such clusters may be called as "hot" (low retention,
high-speed disks, used for operative monitoring) and "cold" (long term retention,
slower/cheaper disks, low resolution data). With help of `vmalert`, user can setup
recording rules to process raw data from "hot" cluster (by applying additional transformations
or reducing resolution) and push results to "cold" cluster.

`vmalert` configuration flags:

```
./bin/vmalert -rule=downsampling-rules.yml \                                        # Path to the file with rules configuration. Supports wildcard
    -datasource.url=http://raw-cluster-vmselect:8481/select/0/prometheus            # vmselect addr for executing recording rules expressions
    -remoteWrite.url=http://aggregated-cluster-vminsert:8480/insert/0/prometheus    # vminsert addr to persist recording rules results
```

<img alt="vmalert multi cluster" src="vmalert_multicluster.png">

Please note, [replay](#rules-backfilling) feature may be used for transforming historical data.

Flags `-remoteRead.url` and `-notifier.url` are omitted since we assume only recording rules are used.

See also [stream aggregation](https://docs.victoriametrics.com/stream-aggregation.html) and [downsampling](https://docs.victoriametrics.com/#downsampling).

#### Multiple remote writes

For persisting recording or alerting rule results `vmalert` requires `-remoteWrite.url` to be set.
But this flag supports only one destination. To persist rule results to multiple destinations
we recommend using [vmagent](https://docs.victoriametrics.com/vmagent.html) as fan-out proxy:

<img alt="vmalert multiple remote write destinations" src="vmalert_multiple_rw.png">

In this topology, `vmalert` is configured to persist rule results to `vmagent`. And `vmagent`
is configured to fan-out received data to two or more destinations.
Using `vmagent` as a proxy provides additional benefits such as
[data persisting when storage is unreachable](https://docs.victoriametrics.com/vmagent.html#replication-and-high-availability),
or time series modification via [relabeling](https://docs.victoriametrics.com/vmagent.html#relabeling).


### Web

`vmalert` runs a web-server (`-httpListenAddr`) for serving metrics and alerts endpoints:

* `http://<vmalert-addr>` - UI;
* `http://<vmalert-addr>/api/v1/rules` - list of all loaded groups and rules;
* `http://<vmalert-addr>/api/v1/alerts` - list of all active alerts;
* `http://<vmalert-addr>/vmalert/api/v1/alert?group_id=<group_id>&alert_id=<alert_id>` - get alert status in JSON format.
  Used as alert source in AlertManager.
* `http://<vmalert-addr>/vmalert/alert?group_id=<group_id>&alert_id=<alert_id>` - get alert status in web UI.
* `http://<vmalert-addr>/vmalert/rule?group_id=<group_id>&rule_id=<rule_id>` - get rule status in web UI.
* `http://<vmalert-addr>/metrics` - application metrics.
* `http://<vmalert-addr>/-/reload` - hot configuration reload.

`vmalert` web UI can be accessed from [single-node version of VictoriaMetrics](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html)
and from [cluster version of VictoriaMetrics](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html).
This may be used for better integration with Grafana unified alerting system. See the following docs for details:

* [How to query vmalert from single-node VictoriaMetrics](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html#vmalert)
* [How to query vmalert from VictoriaMetrics cluster](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html#vmalert)


## Graphite

vmalert sends requests to `<-datasource.url>/render?format=json` during evaluation of alerting and recording rules
if the corresponding group or rule contains `type: "graphite"` config option. It is expected that the `<-datasource.url>/render`
implements [Graphite Render API](https://graphite.readthedocs.io/en/stable/render_api.html) for `format=json`.
When using vmalert with both `graphite` and `prometheus` rules configured against cluster version of VM do not forget
to set `-datasource.appendTypePrefix` flag to `true`, so vmalert can adjust URL prefix automatically based on the query type.

## Rules backfilling

vmalert supports alerting and recording rules backfilling (aka `replay`). In replay mode vmalert
can read the same rules configuration as normal, evaluate them on the given time range and backfill
results via remote write to the configured storage. vmalert supports any PromQL/MetricsQL compatible
data source for backfilling.

Please note, that response caching may lead to unexpected results during and after backfilling process.
In order to avoid this you need to reset cache contents or disable caching when using backfilling
as described in [backfilling docs](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html#backfilling).

See a blogpost about [Rules backfilling via vmalert](https://victoriametrics.com/blog/rules-replay/).

### How it works

In `replay` mode vmalert works as a cli-tool and exits immediately after work is done.
To run vmalert in `replay` mode:

```
./bin/vmalert -rule=path/to/your.rules \        # path to files with rules you usually use with vmalert
    -datasource.url=http://localhost:8428 \     # Prometheus HTTP API compatible datasource
    -remoteWrite.url=http://localhost:8428 \    # remote write compatible storage to persist results
    -replay.timeFrom=2021-05-11T07:21:43Z \     # time from begin replay
    -replay.timeTo=2021-05-29T18:40:43Z         # time to finish replay
```

The output of the command will look like the following:

```
Replay mode:
from:   2021-05-11 07:21:43 +0000 UTC   # set by -replay.timeFrom
to:     2021-05-29 18:40:43 +0000 UTC   # set by -replay.timeTo
max data points per request: 1000       # set by -replay.maxDatapointsPerQuery

Group "ReplayGroup"
interval:       1m0s
requests to make:       27
max range per request:  16h40m0s
> Rule "type:vm_cache_entries:rate5m" (ID: 1792509946081842725)
27 / 27 [----------------------------------------------------------------------------------------------------] 100.00% 78 p/s
> Rule "go_cgo_calls_count:rate5m" (ID: 17958425467471411582)
27 / 27 [-----------------------------------------------------------------------------------------------------] 100.00% ? p/s

Group "vmsingleReplay"
interval:       30s
requests to make:       54
max range per request:  8h20m0s
> Rule "RequestErrorsToAPI" (ID: 17645863024999990222)
54 / 54 [-----------------------------------------------------------------------------------------------------] 100.00% ? p/s
> Rule "TooManyLogs" (ID: 9042195394653477652)
54 / 54 [-----------------------------------------------------------------------------------------------------] 100.00% ? p/s
2021-06-07T09:59:12.098Z        info    app/vmalert/replay.go:68        replay finished! Imported 511734 samples
```

In `replay` mode all groups are executed sequentially one-by-one. Rules within the group are
executed sequentially as well (`concurrency` setting is ignored). Vmalert sends rule's expression
to [/query_range](https://docs.victoriametrics.com/keyConcepts.html#range-query) endpoint
of the configured `-datasource.url`. Returned data is then processed according to the rule type and
backfilled to `-remoteWrite.url` via [remote Write protocol](https://prometheus.io/docs/prometheus/latest/storage/#remote-storage-integrations).
Vmalert respects `evaluationInterval` value set by flag or per-group during the replay.
Vmalert automatically disables caching on VictoriaMetrics side by sending `nocache=1` param. It allows
to prevent cache pollution and unwanted time range boundaries adjustment during backfilling.

#### Recording rules

The result of recording rules `replay` should match with results of normal rules evaluation.

#### Alerting rules

The result of alerting rules `replay` is time series reflecting [alert's state](#alerts-state-on-restarts).
To see if `replayed` alert has fired in the past use the following PromQL/MetricsQL expression:

```
ALERTS{alertname="your_alertname", alertstate="firing"}
```

Execute the query against storage which was used for `-remoteWrite.url` during the `replay`.

### Additional configuration

There are following non-required `replay` flags:

* `-replay.maxDatapointsPerQuery` - the max number of data points expected to receive in one request.
  In two words, it affects the max time range for every `/query_range` request. The higher the value,
  the fewer requests will be issued during `replay`.
* `-replay.ruleRetryAttempts` - when datasource fails to respond vmalert will make this number of retries
  per rule before giving up.
* `-replay.rulesDelay` - delay between sequential rules execution. Important in cases if there are chaining
  (rules which depend on each other) rules. It is expected, that remote storage will be able to persist
  previously accepted data during the delay, so data will be available for the subsequent queries.
  Keep it equal or bigger than `-remoteWrite.flushInterval`.
* `-replay.disableProgressBar` - whether to disable progress bar which shows progress work.
  Progress bar may generate a lot of log records, which is not formatted as standard VictoriaMetrics logger.
  It could break logs parsing by external system and generate additional load on it.

See full description for these flags in `./vmalert -help`.

### Limitations

* Graphite engine isn't supported yet;
* `query` template function is disabled for performance reasons (might be changed in future);
* `limit` group's param has no effect during replay (might be changed in future);

## Unit Testing for Rules

You can use `vmalert` to run unit tests for alerting and recording rules.
In unit test mode vmalert performs the following actions:
* sets up an isolated VictoriaMetrics instance;
* simulates the periodic ingestion of time series;
* queries the ingested data for recording and alerting rules evaluation;
* tests whether the firing alerts or resulting recording rules match the expected results. 

See how to run vmalert in unit test mode below:
```
# Run vmalert with one or multiple test files via -unittestFile cmd-line flag
./vmalert -unittestFile=test1.yaml -unittestFile=test2.yaml
```

vmalert is compatible with [Prometheus config format for tests](https://prometheus.io/docs/prometheus/latest/configuration/unit_testing_rules/#test-file-format)
except `promql_expr_test` field. Use `metricsql_expr_test` field name instead. The name is different because vmalert 
validates and executes [MetricsQL](https://docs.victoriametrics.com/MetricsQL.html) expressions, 
which aren't always backward compatible with [PromQL](https://prometheus.io/docs/prometheus/latest/querying/basics/).

### Test file format

The configuration format for files specified in `-unittestFile` cmd-line flag is the following:
```
# Path to the files or http url containing [rule groups](https://docs.victoriametrics.com/vmalert.html#groups) configuration.
# Enterprise version of vmalert supports S3 and GCS paths to rules.
rule_files:
  [ - <string> ]

# The evaluation interval for rules specified in `rule_files`
[ evaluation_interval: <duration> | default = 1m ]

# Groups listed below will be evaluated by order.
# Not All the groups need not be mentioned, if not, they will be evaluated by define order in rule_files.
group_eval_order:
  [ - <string> ]

# The list of unit test files to be checked during evaluation.
tests:
  [ - <test_group> ]
```

#### `<test_group>`

```
# Interval between samples for input series
interval: <duration>
# Time series to persist into the database according to configured <interval> before running tests.
input_series:
  [ - <series> ]

# Name of the test group, optional
[ name: <string> ]

# Unit tests for alerting rules
alert_rule_test:
  [ - <alert_test_case> ]

# Unit tests for Metricsql expressions.
metricsql_expr_test:
  [ - <metricsql_expr_test> ]

# External labels accessible for templating.
external_labels:
  [ <labelname>: <string> ... ]

```

#### `<series>`

```
# series in the following format '<metric name>{<label name>=<label value>, ...}'
# Examples:
#      series_name{label1="value1", label2="value2"}
#      go_goroutines{job="prometheus", instance="localhost:9090"}
series: <string>

# values support several special equations:
#     'a+bxc' becomes 'a a+b a+(2*b) a+(3*b) … a+(c*b)'
#     Read this as series starts at a, then c further samples incrementing by b.
#     'a-bxc' becomes 'a a-b a-(2*b) a-(3*b) … a-(c*b)'
#     Read this as series starts at a, then c further samples decrementing by b (or incrementing by negative b).
#    '_' represents a missing sample from scrape
# Examples:
#     1. '-2+4x3' becomes '-2 2 6 10' - series starts at -2, then 3 further samples incrementing by 4.
#     2. ' 1-2x4' becomes '1 -1 -3 -5 -7' - series starts at 1, then 4 further samples decrementing by 2.
#     3. ' 1x4' becomes '1 1 1 1 1' - shorthand for '1+0x4', series starts at 1, then 4 further samples incrementing by 0.
#     4. ' 1 _x3' becomes '1 _ _ _ ' - the missing sample cannot increment, so 3 missing samples are produced by the '_x3' expression.
values: <string>
```

#### `<alert_test_case>`

vmalert by default adds `alertgroup` and `alertname` to the generated alerts and time series. 
So you will need to specify both `groupname` and `alertname` under a single `<alert_test_case>`, 
but no need to add them under `exp_alerts`.
You can also pass `--disableAlertgroupLabel` to prevent vmalert from adding `alertgroup` label.

```
# The time elapsed from time=0s when this alerting rule should be checked.
# Means this rule should be firing at this point, or shouldn't be firing if 'exp_alerts' is empty.
eval_time: <duration>

# Name of the group name to be tested.
groupname: <string>

# Name of the alert to be tested.
alertname: <string>

# List of the expected alerts that are firing under the given alertname at
# the given evaluation time. If you want to test if an alerting rule should
# not be firing, then you can mention only the fields above and leave 'exp_alerts' empty.
exp_alerts:
  [ - <alert> ]
```

#### `<alert>`

```
# These are the expanded labels and annotations of the expected alert.
# Note: labels also include the labels of the sample associated with the alert
exp_labels:
  [ <labelname>: <string> ]
exp_annotations:
  [ <labelname>: <string> ]
```

#### `<metricsql_expr_test>`

```
# Expression to evaluate
expr: <string>

# The time elapsed from time=0s when this expression be evaluated.
eval_time: <duration>

# Expected samples at the given evaluation time.
exp_samples:
  [ - <sample> ]
```

#### `<sample>`

```
# Labels of the sample in usual series notation '<metric name>{<label name>=<label value>, ...}'
# Examples:
#      series_name{label1="value1", label2="value2"}
#      go_goroutines{job="prometheus", instance="localhost:9090"}
labels: <string>

# The expected value of the Metricsql expression.
value: <number>
```

### Example

This is an example input file for unit testing which will pass.
`test.yaml` is the test file which follows the syntax above and `alerts.yaml` contains the alerting rules.

With `rules.yaml` in the same directory, run `./vmalert -unittestFile=./unittest/testdata/test.yaml`.

#### `test.yaml`

```
rule_files:
  - rules.yaml

evaluation_interval: 1m

tests:
  - interval: 1m
    input_series:
      - series: 'up{job="prometheus", instance="localhost:9090"}'
        values: "0+0x1440"

    metricsql_expr_test:
      - expr: suquery_interval_test
        eval_time: 4m
        exp_samples:
          - labels: '{__name__="suquery_interval_test", datacenter="dc-123", instance="localhost:9090", job="prometheus"}'
            value: 1

    alert_rule_test:
      - eval_time: 2h
        groupname: group1
        alertname: InstanceDown
        exp_alerts:
          - exp_labels:
              job: prometheus
              severity: page
              instance: localhost:9090
              datacenter: dc-123
            exp_annotations:
              summary: "Instance localhost:9090 down"
              description: "localhost:9090 of job prometheus has been down for more than 5 minutes."

      - eval_time: 0
        groupname: group1
        alertname: AlwaysFiring
        exp_alerts:
          - exp_labels:
              datacenter: dc-123

      - eval_time: 0
        groupname: group1
        alertname: InstanceDown
        exp_alerts: []

    external_labels:
      datacenter: dc-123
```

#### `alerts.yaml`

```
# This is the rules file.

groups:
  - name: group1
    rules:
      - alert: InstanceDown
        expr: up == 0
        for: 5m
        labels:
          severity: page
        annotations:
          summary: "Instance {{ $labels.instance }} down"
          description: "{{ $labels.instance }} of job {{ $labels.job }} has been down for more than 5 minutes."
      - alert: AlwaysFiring
        expr: 1

  - name: group2
    rules:
      - record: job:test:count_over_time1m
        expr: sum without(instance) (count_over_time(test[1m]))
      - record: suquery_interval_test
        expr: count_over_time(up[5m:])
```

## Monitoring

`vmalert` exports various metrics in Prometheus exposition format at `http://vmalert-host:8880/metrics` page.
The default list of alerting rules for these metric can be found [here](https://github.com/VictoriaMetrics/VictoriaMetrics/tree/master/deployment/docker).
We recommend setting up regular scraping of this page either through `vmagent` or by Prometheus so that the exported
metrics may be analyzed later.

Use the official [Grafana dashboard](https://grafana.com/grafana/dashboards/14950-victoriametrics-vmalert/) for `vmalert` overview. 
Graphs on this dashboard contain useful hints - hover the `i` icon in the top left corner of each graph in order to read it.
If you have suggestions for improvements or have found a bug - please open an issue on github or add
a review to the dashboard.

## Troubleshooting

### Data delay

Data delay is one of the most common issues with rules execution.
vmalert executes configured rules within certain intervals at specifics timestamps. 
It expects that the data is already present in configured `-datasource.url` at the moment of time when rule is executed:

<img alt="vmalert expected evaluation" src="vmalert_ts_normal.gif">

Usually, troubles start to appear when data in `-datasource.url` is delayed or absent. In such cases, evaluations
may get empty response from the datasource and produce empty recording rules or reset alerts state:

<img alt="vmalert evaluation when data is delayed" src="vmalert_ts_data_delay.gif">

Try the following recommendations to reduce the chance of hitting the data delay issue:

* Always configure group's `evaluationInterval` to be bigger or at least equal to 
[time series resolution](https://docs.victoriametrics.com/keyConcepts.html#time-series-resolution);
* Ensure that `[duration]` value is at least twice bigger than 
[time series resolution](https://docs.victoriametrics.com/keyConcepts.html#time-series-resolution). For example,
if expression is `rate(my_metric[2m]) > 0` then ensure that `my_metric` resolution is at least `1m` or better `30s`. 
If you use VictoriaMetrics as datasource, `[duration]` can be omitted and VictoriaMetrics will adjust it automatically.
* If you know in advance, that data in datasource is delayed - try changing vmalerts `-datasource.lookback`
command-line flag to add a time shift for evaluations. Or extend `[duration]` to tolerate the delay.
For example, `max_over_time(errors_total[10m]) > 0` will be active even if there is no data in datasource for last `9m`.
* If [time series resolution](https://docs.victoriametrics.com/keyConcepts.html#time-series-resolution)
in datasource is inconsistent or `>=5min` - try changing vmalerts `-datasource.queryStep` command-line flag to specify
how far search query can lookback for the recent datapoint. The recommendation is to have the step 
at least two times bigger than the resolution.

> Please note, data delay is inevitable in distributed systems. And it is better to account for it instead of ignoring.

By default, recently written samples to VictoriaMetrics aren't visible for queries for up to 30s
(see `-search.latencyOffset` command-line flag at vmselect). Such delay is needed to eliminate risk of incomplete
data on the moment of querying, since metrics collectors won't be able to deliver the data in time.

### Alerts state

Sometimes, it is not clear why some specific alert fired or didn't fire. It is very important to remember, that
alerts with `for: 0` fire immediately when their expression becomes true. And alerts with `for > 0` will fire only
after multiple consecutive evaluations, and at each evaluation their expression must be true. If at least one evaluation
becomes false, then alert's state resets to the initial state.

If `-remoteWrite.url` command-line flag is configured, vmalert will persist alert's state in form of time series
`ALERTS` and `ALERTS_FOR_STATE` to the specified destination. Such time series can be then queried via
[vmui](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html#vmui) or Grafana to track how alerts state
changed in time.

vmalert stores last `-rule.updateEntriesLimit` (or `update_entries_limit` [per-rule config](https://docs.victoriametrics.com/vmalert.html#alerting-rules)) 
state updates for each rule starting from [v1.86](https://docs.victoriametrics.com/CHANGELOG.html#v1860).
To check updates, click on `Details` link next to rule's name on `/vmalert/groups` page 
and check the `Last updates` section:

<img alt="vmalert state" src="vmalert_state.png">

Rows in the section represent ordered rule evaluations and their results. The column `curl` contains an example of
HTTP request sent by vmalert to the `-datasource.url` during evaluation. If specific state shows that there were
no samples returned and curl command returns data - then it is very likely there was no data in datasource on the
moment when rule was evaluated.

### Debug mode

vmalert allows configuring more detailed logging for specific alerting rule starting from [v1.82](https://docs.victoriametrics.com/CHANGELOG.html#v1820).
Just set `debug: true` in rule's configuration and vmalert will start printing additional log messages:
```terminal
2022-09-15T13:35:41.155Z  DEBUG rule "TestGroup":"Conns" (2601299393013563564) at 2022-09-15T15:35:41+02:00: query returned 0 samples (elapsed: 5.896041ms)
2022-09-15T13:35:56.149Z  DEBUG datasource request: executing POST request with params "denyPartialResponse=true&query=sum%28vm_tcplistener_conns%7Binstance%3D%22localhost%3A8429%22%7D%29+by%28instance%29+%3E+0&step=15s&time=1663248945"
2022-09-15T13:35:56.178Z  DEBUG rule "TestGroup":"Conns" (2601299393013563564) at 2022-09-15T15:35:56+02:00: query returned 1 samples (elapsed: 28.368208ms)
2022-09-15T13:35:56.178Z  DEBUG datasource request: executing POST request with params "denyPartialResponse=true&query=sum%28vm_tcplistener_conns%7Binstance%3D%22localhost%3A8429%22%7D%29&step=15s&time=1663248945"
2022-09-15T13:35:56.179Z  DEBUG rule "TestGroup":"Conns" (2601299393013563564) at 2022-09-15T15:35:56+02:00: alert 10705778000901301787 {alertgroup="TestGroup",alertname="Conns",cluster="east-1",instance="localhost:8429",replica="a"} created in state PENDING
...
2022-09-15T13:36:56.153Z  DEBUG rule "TestGroup":"Conns" (2601299393013563564) at 2022-09-15T15:36:56+02:00: alert 10705778000901301787 {alertgroup="TestGroup",alertname="Conns",cluster="east-1",instance="localhost:8429",replica="a"} PENDING => FIRING: 1m0s since becoming active at 2022-09-15 15:35:56.126006 +0200 CEST m=+39.384575417
```

### Never-firing alerts

vmalert can detect if alert's expression doesn't match any time series in runtime 
starting from [v1.91](https://docs.victoriametrics.com/CHANGELOG.html#v1910). This problem usually happens
when alerting expression selects time series which aren't present in the datasource (i.e. wrong `job` label)
or there is a typo in the series selector (i.e. `env=rpod`). Such alerting rules will be marked with special icon in 
vmalerts UI and exposed via `vmalert_alerting_rules_last_evaluation_series_fetched` metric. The metric value will
show how many time series were matched before the filtering by rule's expression. If metric value is `-1`, then
this feature is not supported by the datasource (old versions of VictoriaMetrics). The following expression can be
used to detect rules matching no series:
```
max(vmalert_alerting_rules_last_evaluation_series_fetched) by(group, alertname) == 0
```

See more details [here](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/4039).
This feature is available only if vmalert is using VictoriaMetrics v1.90 or higher as a datasource.

### Series with the same labelset

vmalert can produce the following error message during rules evaluation:
```
result contains metrics with the same labelset after applying rule labels
```

The error means there is a collision between [time series](https://docs.victoriametrics.com/keyConcepts.html#time-series)
after applying extra labels to result.

For example, a rule with `expr: foo > 0` returns two distinct time series in response:
```
foo{bar="baz"} 1
foo{bar="qux"} 2
```

If user configures `-external.label=bar=baz` cmd-line flag to enforce
adding `bar="baz"` label-value pair, then time series won't be distinct anymore:
```
foo{bar="baz"} 1
foo{bar="baz"} 2 # 'bar' label was overriden by `-external.label=bar=baz
```

The same issue can be caused by collision of configured `labels` on [Group](#groups) or [Rule](#rules) levels.
To fix it one should avoid collisions by carefully picking label overrides in configuration.


## Profiling

`vmalert` provides handlers for collecting the following [Go profiles](https://blog.golang.org/profiling-go-programs):

* Memory profile. It can be collected with the following command (replace `0.0.0.0` with hostname if needed):

<div class="with-copy" markdown="1">

```console
curl http://0.0.0.0:8880/debug/pprof/heap > mem.pprof
```

</div>

* CPU profile. It can be collected with the following command (replace `0.0.0.0` with hostname if needed):

<div class="with-copy" markdown="1">

```console
curl http://0.0.0.0:8880/debug/pprof/profile > cpu.pprof
```

</div>

The command for collecting CPU profile waits for 30 seconds before returning.

The collected profiles may be analyzed with [go tool pprof](https://github.com/google/pprof).
It is safe sharing the collected profiles from security point of view, since they do not contain sensitive information.

## Configuration

### Flags

Pass `-help` to `vmalert` in order to see the full list of supported
command-line flags with their descriptions.

The shortlist of configuration flags is the following:
{% raw  %}
```console
  -clusterMode
     If clusterMode is enabled, then vmalert automatically adds the tenant specified in config groups to -datasource.url, -remoteWrite.url and -remoteRead.url. See https://docs.victoriametrics.com/vmalert.html#multitenancy . This flag is available only in VictoriaMetrics enterprise. See https://docs.victoriametrics.com/enterprise.html
  -configCheckInterval duration
     Interval for checking for changes in '-rule' or '-notifier.config' files. By default, the checking is disabled. Send SIGHUP signal in order to force config check for changes.
  -datasource.appendTypePrefix
     Whether to add type prefix to -datasource.url based on the query type. Set to true if sending different query types to the vmselect URL.
  -datasource.basicAuth.password string
     Optional basic auth password for -datasource.url
  -datasource.basicAuth.passwordFile string
     Optional path to basic auth password to use for -datasource.url
  -datasource.basicAuth.username string
     Optional basic auth username for -datasource.url
  -datasource.bearerToken string
     Optional bearer auth token to use for -datasource.url.
  -datasource.bearerTokenFile string
     Optional path to bearer token file to use for -datasource.url.
  -datasource.disableKeepAlive
     Whether to disable long-lived connections to the datasource. If true, disables HTTP keep-alives and will only use the connection to the server for a single HTTP request.
  -datasource.disableStepParam
     Whether to disable adding 'step' param to the issued instant queries. This might be useful when using vmalert with datasources that do not support 'step' param for instant queries, like Google Managed Prometheus. It is not recommended to enable this flag if you use vmalert with VictoriaMetrics.
  -datasource.headers string
     Optional HTTP extraHeaders to send with each request to the corresponding -datasource.url. For example, -datasource.headers='My-Auth:foobar' would send 'My-Auth: foobar' HTTP header with every request to the corresponding -datasource.url. Multiple headers must be delimited by '^^': -datasource.headers='header1:value1^^header2:value2'
  -datasource.lookback duration
     Lookback defines how far into the past to look when evaluating queries. For example, if the datasource.lookback=5m then param "time" with value now()-5m will be added to every query.
  -datasource.maxIdleConnections int
     Defines the number of idle (keep-alive connections) to each configured datasource. Consider setting this value equal to the value: groups_total * group.concurrency. Too low a value may result in a high number of sockets in TIME_WAIT state. (default 100)
  -datasource.oauth2.clientID string
     Optional OAuth2 clientID to use for -datasource.url. 
  -datasource.oauth2.clientSecret string
     Optional OAuth2 clientSecret to use for -datasource.url.
  -datasource.oauth2.clientSecretFile string
     Optional OAuth2 clientSecretFile to use for -datasource.url. 
  -datasource.oauth2.scopes string
     Optional OAuth2 scopes to use for -datasource.url. Scopes must be delimited by ';'
  -datasource.oauth2.tokenUrl string
     Optional OAuth2 tokenURL to use for -datasource.url.
  -datasource.queryStep duration
     How far a value can fallback to when evaluating queries. For example, if -datasource.queryStep=15s then param "step" with value "15s" will be added to every query. If set to 0, rule's evaluation interval will be used instead. (default 5m0s)
  -datasource.queryTimeAlignment
     Whether to align "time" parameter with evaluation interval.Alignment supposed to produce deterministic results despite number of vmalert replicas or time they were started. See more details here https://github.com/VictoriaMetrics/VictoriaMetrics/pull/1257 (default true)
  -datasource.roundDigits int
     Adds "round_digits" GET param to datasource requests. In VM "round_digits" limits the number of digits after the decimal point in response values.
  -datasource.showURL
     Whether to show -datasource.url in the exported metrics. It is hidden by default, since it can contain sensitive info such as auth key
  -datasource.tlsCAFile string
     Optional path to TLS CA file to use for verifying connections to -datasource.url. By default, system CA is used
  -datasource.tlsCertFile string
     Optional path to client-side TLS certificate file to use when connecting to -datasource.url
  -datasource.tlsInsecureSkipVerify
     Whether to skip tls verification when connecting to -datasource.url
  -datasource.tlsKeyFile string
     Optional path to client-side TLS certificate key to use when connecting to -datasource.url
  -datasource.tlsServerName string
     Optional TLS server name to use for connections to -datasource.url. By default, the server name from -datasource.url is used
  -datasource.url string
     Datasource compatible with Prometheus HTTP API. It can be single node VictoriaMetrics or vmselect URL. Required parameter. E.g. http://127.0.0.1:8428 . See also -remoteRead.disablePathAppend and -datasource.showURL
  -defaultTenant.graphite string
     Default tenant for Graphite alerting groups. See https://docs.victoriametrics.com/vmalert.html#multitenancy .This flag is available only in VictoriaMetrics enterprise. See https://docs.victoriametrics.com/enterprise.html
  -defaultTenant.prometheus string
     Default tenant for Prometheus alerting groups. See https://docs.victoriametrics.com/vmalert.html#multitenancy . This flag is available only in VictoriaMetrics enterprise. See https://docs.victoriametrics.com/enterprise.html
  -disableAlertgroupLabel
     Whether to disable adding group's Name as label to generated alerts and time series.
  -dryRun
     Whether to check only config files without running vmalert. The rules file are validated. The -rule flag must be specified.
  -enableTCP6
     Whether to enable IPv6 for listening and dialing. By default, only IPv4 TCP and UDP are used
  -envflag.enable
     Whether to enable reading flags from environment variables in addition to the command line. Command line flag values have priority over values from environment vars. Flags are read only from the command line if this flag isn't set. See https://docs.victoriametrics.com/#environment-variables for more details
  -envflag.prefix string
     Prefix for environment variables if -envflag.enable is set
  -eula
     By specifying this flag, you confirm that you have an enterprise license and accept the EULA https://victoriametrics.com/assets/VM_EULA.pdf . This flag is available only in VictoriaMetrics enterprise. See https://docs.victoriametrics.com/enterprise.html
  -evaluationInterval duration
     How often to evaluate the rules (default 1m0s)
  -external.alert.source string
     External Alert Source allows to override the Source link for alerts sent to AlertManager for cases where you want to build a custom link to Grafana, Prometheus or any other service. Supports templating - see https://docs.victoriametrics.com/vmalert.html#templating . For example, link to Grafana: -external.alert.source='explore?orgId=1&left={"datasource":"VictoriaMetrics","queries":[{"expr":{{$expr|jsonEscape|queryEscape}},"refId":"A"}],"range":{"from":"now-1h","to":"now"}}'. Link to VMUI: -external.alert.source='vmui/#/?g0.expr={{.Expr|queryEscape}}'. If empty 'vmalert/alert?group_id={{.GroupID}}&alert_id={{.AlertID}}' is used.
  -external.label array
     Optional label in the form 'Name=value' to add to all generated recording rules and alerts. Pass multiple -label flags in order to add multiple label sets.
     Supports an array of values separated by comma or specified via multiple flags.
  -external.url string
     External URL is used as alert's source for sent alerts to the notifier. By default, hostname is used as address.
  -flagsAuthKey string
     Auth key for /flags endpoint. It must be passed via authKey query arg. It overrides httpAuth.* settings
  -fs.disableMmap
     Whether to use pread() instead of mmap() for reading data files. By default, mmap() is used for 64-bit arches and pread() is used for 32-bit arches, since they cannot read data files bigger than 2^32 bytes in memory. mmap() is usually faster for reading small data chunks than pread()
  -http.connTimeout duration
     Incoming http connections are closed after the configured timeout. This may help to spread the incoming load among a cluster of services behind a load balancer. Please note that the real timeout may be bigger by up to 10% as a protection against the thundering herd problem (default 2m0s)
  -http.disableResponseCompression
     Disable compression of HTTP responses to save CPU resources. By default, compression is enabled to save network bandwidth
  -http.idleConnTimeout duration
     Timeout for incoming idle http connections (default 1m0s)
  -http.maxGracefulShutdownDuration duration
     The maximum duration for a graceful shutdown of the HTTP server. A highly loaded server may require increased value for a graceful shutdown (default 7s)
  -http.pathPrefix string
     An optional prefix to add to all the paths handled by http server. For example, if '-http.pathPrefix=/foo/bar' is set, then all the http requests will be handled on '/foo/bar/*' paths. This may be useful for proxied requests. See https://www.robustperception.io/using-external-urls-and-proxies-with-prometheus
  -http.shutdownDelay duration
     Optional delay before http server shutdown. During this delay, the server returns non-OK responses from /health page, so load balancers can route new requests to other servers
  -httpAuth.password string
     Password for HTTP server's Basic Auth. The authentication is disabled if -httpAuth.username is empty
  -httpAuth.username string
     Username for HTTP server's Basic Auth. The authentication is disabled if empty. See also -httpAuth.password
  -httpListenAddr string
     Address to listen for http connections. See also -httpListenAddr.useProxyProtocol (default ":8880")
  -httpListenAddr.useProxyProtocol
     Whether to use proxy protocol for connections accepted at -httpListenAddr . See https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt . With enabled proxy protocol http server cannot serve regular /metrics endpoint. Use -pushmetrics.url for metrics pushing
  -internStringCacheExpireDuration duration
     The expiry duration for caches for interned strings. See https://en.wikipedia.org/wiki/String_interning . See also -internStringMaxLen and -internStringDisableCache (default 6m0s)
  -internStringDisableCache
     Whether to disable caches for interned strings. This may reduce memory usage at the cost of higher CPU usage. See https://en.wikipedia.org/wiki/String_interning . See also -internStringCacheExpireDuration and -internStringMaxLen
  -internStringMaxLen int
     The maximum length for strings to intern. A lower limit may save memory at the cost of higher CPU usage. See https://en.wikipedia.org/wiki/String_interning . See also -internStringDisableCache and -internStringCacheExpireDuration (default 500)
  -loggerDisableTimestamps
     Whether to disable writing timestamps in logs
  -loggerErrorsPerSecondLimit int
     Per-second limit on the number of ERROR messages. If more than the given number of errors are emitted per second, the remaining errors are suppressed. Zero values disable the rate limit
  -loggerFormat string
     Format for logs. Possible values: default, json (default "default")
  -loggerJSONFields string
     Allows renaming fields in JSON formatted logs. Example: "ts:timestamp,msg:message" renames "ts" to "timestamp" and "msg" to "message". Supported fields: ts, level, caller, msg
  -loggerLevel string
     Minimum level of errors to log. Possible values: INFO, WARN, ERROR, FATAL, PANIC (default "INFO")
  -loggerOutput string
     Output for the logs. Supported values: stderr, stdout (default "stderr")
  -loggerTimezone string
     Timezone to use for timestamps in logs. Timezone must be a valid IANA Time Zone. For example: America/New_York, Europe/Berlin, Etc/GMT+3 or Local (default "UTC")
  -loggerWarnsPerSecondLimit int
     Per-second limit on the number of WARN messages. If more than the given number of warns are emitted per second, then the remaining warns are suppressed. Zero values disable the rate limit
  -memory.allowedBytes size
     Allowed size of system memory VictoriaMetrics caches may occupy. This option overrides -memory.allowedPercent if set to a non-zero value. Too low a value may increase the cache miss rate usually resulting in higher CPU and disk IO usage. Too high a value may evict too much data from the OS page cache resulting in higher disk IO usage
     Supports the following optional suffixes for size values: KB, MB, GB, TB, KiB, MiB, GiB, TiB (default 0)
  -memory.allowedPercent float
     Allowed percent of system memory VictoriaMetrics caches may occupy. See also -memory.allowedBytes. Too low a value may increase cache miss rate usually resulting in higher CPU and disk IO usage. Too high a value may evict too much data from the OS page cache which will result in higher disk IO usage (default 60)
  -metricsAuthKey string
     Auth key for /metrics endpoint. It must be passed via authKey query arg. It overrides httpAuth.* settings
  -notifier.basicAuth.password array
     Optional basic auth password for -notifier.url
     Supports an array of values separated by comma or specified via multiple flags.
  -notifier.basicAuth.passwordFile array
     Optional path to basic auth password file for -notifier.url
     Supports an array of values separated by comma or specified via multiple flags.
  -notifier.basicAuth.username array
     Optional basic auth username for -notifier.url
     Supports an array of values separated by comma or specified via multiple flags.
  -notifier.bearerToken array
     Optional bearer token for -notifier.url
     Supports an array of values separated by comma or specified via multiple flags.
  -notifier.bearerTokenFile array
     Optional path to bearer token file for -notifier.url
     Supports an array of values separated by comma or specified via multiple flags.
  -notifier.config string
     Path to configuration file for notifiers
  -notifier.oauth2.clientID array
     Optional OAuth2 clientID to use for -notifier.url. If multiple args are set, then they are applied independently for the corresponding -notifier.url
     Supports an array of values separated by comma or specified via multiple flags.
  -notifier.oauth2.clientSecret array
     Optional OAuth2 clientSecret to use for -notifier.url. If multiple args are set, then they are applied independently for the corresponding -notifier.url
     Supports an array of values separated by comma or specified via multiple flags.
  -notifier.oauth2.clientSecretFile array
     Optional OAuth2 clientSecretFile to use for -notifier.url. If multiple args are set, then they are applied independently for the corresponding -notifier.url
     Supports an array of values separated by comma or specified via multiple flags.
  -notifier.oauth2.scopes array
     Optional OAuth2 scopes to use for -notifier.url. Scopes must be delimited by ';'. If multiple args are set, then they are applied independently for the corresponding -notifier.url
     Supports an array of values separated by comma or specified via multiple flags.
  -notifier.oauth2.tokenUrl array
     Optional OAuth2 tokenURL to use for -notifier.url. If multiple args are set, then they are applied independently for the corresponding -notifier.url
     Supports an array of values separated by comma or specified via multiple flags.
  -notifier.suppressDuplicateTargetErrors
     Whether to suppress 'duplicate target' errors during discovery
  -notifier.tlsCAFile array
     Optional path to TLS CA file to use for verifying connections to -notifier.url. By default, system CA is used
     Supports an array of values separated by comma or specified via multiple flags.
  -notifier.tlsCertFile array
     Optional path to client-side TLS certificate file to use when connecting to -notifier.url
     Supports an array of values separated by comma or specified via multiple flags.
  -notifier.tlsInsecureSkipVerify array
     Whether to skip tls verification when connecting to -notifier.url
     Supports array of values separated by comma or specified via multiple flags.
  -notifier.tlsKeyFile array
     Optional path to client-side TLS certificate key to use when connecting to -notifier.url
     Supports an array of values separated by comma or specified via multiple flags.
  -notifier.tlsServerName array
     Optional TLS server name to use for connections to -notifier.url. By default, the server name from -notifier.url is used
     Supports an array of values separated by comma or specified via multiple flags.
  -notifier.url array
     Prometheus Alertmanager URL, e.g. http://127.0.0.1:9093. List all Alertmanager URLs if it runs in the cluster mode to ensure high availability.
     Supports an array of values separated by comma or specified via multiple flags.
  -notifier.blackhole bool
     Whether to blackhole alerting notifications. Enable this flag if you want vmalert to evaluate alerting rules without sending any notifications to external receivers (eg. alertmanager). `-notifier.url`, `-notifier.config` and `-notifier.blackhole` are mutually exclusive.
  -pprofAuthKey string
     Auth key for /debug/pprof/* endpoints. It must be passed via authKey query arg. It overrides httpAuth.* settings
  -promscrape.consul.waitTime duration
     Wait time used by Consul service discovery. Default value is used if not set
  -promscrape.consulSDCheckInterval duration
     Interval for checking for changes in Consul. This works only if consul_sd_configs is configured in '-promscrape.config' file. See https://docs.victoriametrics.com/sd_configs.html#consul_sd_configs for details (default 30s)
  -promscrape.discovery.concurrency int
     The maximum number of concurrent requests to Prometheus autodiscovery API (Consul, Kubernetes, etc.) (default 100)
  -promscrape.discovery.concurrentWaitTime duration
     The maximum duration for waiting to perform API requests if more than -promscrape.discovery.concurrency requests are simultaneously performed (default 1m0s)
  -promscrape.dnsSDCheckInterval duration
     Interval for checking for changes in dns. This works only if dns_sd_configs is configured in '-promscrape.config' file. See https://docs.victoriametrics.com/sd_configs.html#dns_sd_configs for details (default 30s)
  -pushmetrics.extraLabel array
     Optional labels to add to metrics pushed to -pushmetrics.url . For example, -pushmetrics.extraLabel='instance="foo"' adds instance="foo" label to all the metrics pushed to -pushmetrics.url
     Supports an array of values separated by comma or specified via multiple flags.
  -pushmetrics.interval duration
     Interval for pushing metrics to -pushmetrics.url (default 10s)
  -pushmetrics.url array
     Optional URL to push metrics exposed at /metrics page. See https://docs.victoriametrics.com/#push-metrics . By default, metrics exposed at /metrics page aren't pushed to any remote storage
     Supports an array of values separated by comma or specified via multiple flags.
  -remoteRead.basicAuth.password string
     Optional basic auth password for -remoteRead.url
  -remoteRead.basicAuth.passwordFile string
     Optional path to basic auth password to use for -remoteRead.url
  -remoteRead.basicAuth.username string
     Optional basic auth username for -remoteRead.url
  -remoteRead.bearerToken string
     Optional bearer auth token to use for -remoteRead.url.
  -remoteRead.bearerTokenFile string
     Optional path to bearer token file to use for -remoteRead.url.
  -remoteRead.disablePathAppend
     Whether to disable automatic appending of '/api/v1/query' path to the configured -datasource.url and -remoteRead.url
  -remoteRead.headers string
     Optional HTTP headers to send with each request to the corresponding -remoteRead.url. For example, -remoteRead.headers='My-Auth:foobar' would send 'My-Auth: foobar' HTTP header with every request to the corresponding -remoteRead.url. Multiple headers must be delimited by '^^': -remoteRead.headers='header1:value1^^header2:value2'
  -remoteRead.ignoreRestoreErrors
     Whether to ignore errors from remote storage when restoring alerts state on startup. DEPRECATED - this flag has no effect and will be removed in the next releases. (default true)
  -remoteRead.lookback duration
     Lookback defines how far to look into past for alerts timeseries. For example, if lookback=1h then range from now() to now()-1h will be scanned. (default 1h0m0s)
  -remoteRead.oauth2.clientID string
     Optional OAuth2 clientID to use for -remoteRead.url.
  -remoteRead.oauth2.clientSecret string
     Optional OAuth2 clientSecret to use for -remoteRead.url.
  -remoteRead.oauth2.clientSecretFile string
     Optional OAuth2 clientSecretFile to use for -remoteRead.url.
  -remoteRead.oauth2.scopes string
     Optional OAuth2 scopes to use for -remoteRead.url. Scopes must be delimited by ';'.
  -remoteRead.oauth2.tokenUrl string
     Optional OAuth2 tokenURL to use for -remoteRead.url. 
  -remoteRead.showURL
     Whether to show -remoteRead.url in the exported metrics. It is hidden by default, since it can contain sensitive info such as auth key
  -remoteRead.tlsCAFile string
     Optional path to TLS CA file to use for verifying connections to -remoteRead.url. By default, system CA is used
  -remoteRead.tlsCertFile string
     Optional path to client-side TLS certificate file to use when connecting to -remoteRead.url
  -remoteRead.tlsInsecureSkipVerify
     Whether to skip tls verification when connecting to -remoteRead.url
  -remoteRead.tlsKeyFile string
     Optional path to client-side TLS certificate key to use when connecting to -remoteRead.url
  -remoteRead.tlsServerName string
     Optional TLS server name to use for connections to -remoteRead.url. By default, the server name from -remoteRead.url is used
  -remoteRead.url vmalert
     Optional URL to datasource compatible with Prometheus HTTP API. It can be single node VictoriaMetrics or vmselect.Remote read is used to restore alerts state.This configuration makes sense only if vmalert was configured with `remoteWrite.url` before and has been successfully persisted its state. E.g. http://127.0.0.1:8428. See also '-remoteRead.disablePathAppend', '-remoteRead.showURL'.
  -remoteWrite.basicAuth.password string
     Optional basic auth password for -remoteWrite.url
  -remoteWrite.basicAuth.passwordFile string
     Optional path to basic auth password to use for -remoteWrite.url
  -remoteWrite.basicAuth.username string
     Optional basic auth username for -remoteWrite.url
  -remoteWrite.bearerToken string
     Optional bearer auth token to use for -remoteWrite.url.
  -remoteWrite.bearerTokenFile string
     Optional path to bearer token file to use for -remoteWrite.url.
  -remoteWrite.concurrency int
     Defines number of writers for concurrent writing into remote querier (default 1)
  -remoteWrite.disablePathAppend
     Whether to disable automatic appending of '/api/v1/write' path to the configured -remoteWrite.url.
  -remoteWrite.flushInterval duration
     Defines interval of flushes to remote write endpoint (default 5s)
  -remoteWrite.headers string
     Optional HTTP headers to send with each request to the corresponding -remoteWrite.url. For example, -remoteWrite.headers='My-Auth:foobar' would send 'My-Auth: foobar' HTTP header with every request to the corresponding -remoteWrite.url. Multiple headers must be delimited by '^^': -remoteWrite.headers='header1:value1^^header2:value2'
  -remoteWrite.maxBatchSize int
     Defines max number of timeseries to be flushed at once (default 1000)
  -remoteWrite.maxQueueSize int
     Defines the max number of pending datapoints to remote write endpoint (default 100000)
  -remoteWrite.oauth2.clientID string
     Optional OAuth2 clientID to use for -remoteWrite.url.
  -remoteWrite.oauth2.clientSecret string
     Optional OAuth2 clientSecret to use for -remoteWrite.url.
  -remoteWrite.oauth2.clientSecretFile string
     Optional OAuth2 clientSecretFile to use for -remoteWrite.url.
  -remoteWrite.oauth2.scopes string
     Optional OAuth2 scopes to use for -notifier.url. Scopes must be delimited by ';'.
  -remoteWrite.oauth2.tokenUrl string
     Optional OAuth2 tokenURL to use for -notifier.url.
  -remoteWrite.retryMaxTime duration
     The max time spent on retry attempts for the failed remote-write request. Change this value if it is expected for remoteWrite.url to be unreachable for more than -remoteWrite.retryMaxTime. See also -remoteWrite.retryMinInterval (default 30s)
  -remoteWrite.retryMinInterval duration
     The minimum delay between retry attempts. Every next retry attempt will double the delay to prevent hammering of remote database. See also -remoteWrite.retryMaxInterval (default 1s)
  -remoteWrite.sendTimeout duration
     Timeout for sending data to the configured -remoteWrite.url. (default 30s)
  -remoteWrite.showURL
     Whether to show -remoteWrite.url in the exported metrics. It is hidden by default, since it can contain sensitive info such as auth key
  -remoteWrite.tlsCAFile string
     Optional path to TLS CA file to use for verifying connections to -remoteWrite.url. By default, system CA is used
  -remoteWrite.tlsCertFile string
     Optional path to client-side TLS certificate file to use when connecting to -remoteWrite.url
  -remoteWrite.tlsInsecureSkipVerify
     Whether to skip tls verification when connecting to -remoteWrite.url
  -remoteWrite.tlsKeyFile string
     Optional path to client-side TLS certificate key to use when connecting to -remoteWrite.url
  -remoteWrite.tlsServerName string
     Optional TLS server name to use for connections to -remoteWrite.url. By default, the server name from -remoteWrite.url is used
  -remoteWrite.url string
     Optional URL to VictoriaMetrics or vminsert where to persist alerts state and recording rules results in form of timeseries. For example, if -remoteWrite.url=http://127.0.0.1:8428 is specified, then the alerts state will be written to http://127.0.0.1:8428/api/v1/write . See also -remoteWrite.disablePathAppend, '-remoteWrite.showURL'.
  -replay.disableProgressBar
     Whether to disable rendering progress bars during the replay. Progress bar rendering might be verbose or break the logs parsing, so it is recommended to be disabled when not used in interactive mode.
  -replay.maxDatapointsPerQuery /query_range
     Max number of data points expected in one request. It affects the max time range for every /query_range request during the replay. The higher the value, the less requests will be made during replay. (default 1000)
  -replay.ruleRetryAttempts int
     Defines how many retries to make before giving up on rule if request for it returns an error. (default 5)
  -replay.rulesDelay duration
     Delay between rules evaluation within the group. Could be important if there are chained rules inside the group and processing need to wait for previous rule results to be persisted by remote storage before evaluating the next rule.Keep it equal or bigger than -remoteWrite.flushInterval. (default 1s)
  -replay.timeFrom string
     The time filter in RFC3339 format to select time series with timestamp equal or higher than provided value. E.g. '2020-01-01T20:07:00Z'
  -replay.timeTo string
     The time filter in RFC3339 format to select timeseries with timestamp equal or lower than provided value. E.g. '2020-01-01T20:07:00Z'
  -rule array
     Path to the files or http url with alerting and/or recording rules.
     Supports hierarchical patterns and regexpes.
     Examples:
      -rule="/path/to/file". Path to a single file with alerting rules.
      -rule="http://<some-server-addr>/path/to/rules". HTTP URL to a page with alerting rules.
      -rule="dir/*.yaml" -rule="/*.yaml" -rule="gcs://vmalert-rules/tenant_%{TENANT_ID}/prod". 
      -rule="dir/**/*.yaml". Includes all the .yaml files in "dir" subfolders recursively.
     Rule files may contain %{ENV_VAR} placeholders, which are substituted by the corresponding env vars.
     
     Enterprise version of vmalert supports S3 and GCS paths to rules.
     For example: gs://bucket/path/to/rules, s3://bucket/path/to/rules
     S3 and GCS paths support only matching by prefix, e.g. s3://bucket/dir/rule_ matches
     all files with prefix rule_ in folder dir.
     See https://docs.victoriametrics.com/vmalert.html#reading-rules-from-object-storage
     
     Supports an array of values separated by comma or specified via multiple flags.
  -rule.configCheckInterval duration
     Interval for checking for changes in '-rule' files. By default, the checking is disabled. Send SIGHUP signal in order to force config check for changes. DEPRECATED - see '-configCheckInterval' instead
  -rule.maxResolveDuration duration
     Limits the maximum duration for automatic alert expiration, which by default is 4 times evaluationInterval of the parent group.
  -rule.resendDelay duration
     Minimum amount of time to wait before resending an alert to notifier
  -rule.templates array
     Path or glob pattern to location with go template definitions
     	for rules annotations templating. Flag can be specified multiple times.
     Examples:
      -rule.templates="/path/to/file". Path to a single file with go templates
      -rule.templates="dir/*.tpl" -rule.templates="/*.tpl". Relative path to all .tpl files in "dir" folder,
     absolute path to all .tpl files in root.
      -rule.templates="dir/**/*.tpl". Includes all the .tpl files in "dir" subfolders recursively.
     
     Supports an array of values separated by comma or specified via multiple flags.
  -rule.updateEntriesLimit int
     Defines the max number of rule's state updates stored in-memory. Rule's updates are available on rule's Details page and are used for debugging purposes. The number of stored updates can be overridden per rule via update_entries_limit param. (default 20)
  -rule.validateExpressions
     Whether to validate rules expressions via MetricsQL engine (default true)
  -rule.validateTemplates
     Whether to validate annotation and label templates (default true)
  -s2a_enable_appengine_dialer
     If true, opportunistically use AppEngine-specific dialer to call S2A.
  -s2a_timeout duration
     Timeout enforced on the connection to the S2A service for handshake. (default 3s)
  -s3.configFilePath string
     Path to file with S3 configs. Configs are loaded from default location if not set.
     See https://docs.aws.amazon.com/general/latest/gr/aws-security-credentials.html . This flag is available only in VictoriaMetrics enterprise. See https://docs.victoriametrics.com/enterprise.html
  -s3.configProfile string
     Profile name for S3 configs. If no set, the value of the environment variable will be loaded (AWS_PROFILE or AWS_DEFAULT_PROFILE), or if both not set, DefaultSharedConfigProfile is used. This flag is available only in VictoriaMetrics enterprise. See https://docs.victoriametrics.com/enterprise.html
  -s3.credsFilePath string
     Path to file with GCS or S3 credentials. Credentials are loaded from default locations if not set.
     See https://cloud.google.com/iam/docs/creating-managing-service-account-keys and https://docs.aws.amazon.com/general/latest/gr/aws-security-credentials.html . This flag is available only in VictoriaMetrics enterprise. See https://docs.victoriametrics.com/enterprise.html
  -s3.customEndpoint string
     Custom S3 endpoint for use with S3-compatible storages (e.g. MinIO). S3 is used if not set. This flag is available only in VictoriaMetrics enterprise. See https://docs.victoriametrics.com/enterprise.html
  -s3.forcePathStyle
     Prefixing endpoint with bucket name when set false, true by default. This flag is available only in VictoriaMetrics enterprise. See https://docs.victoriametrics.com/enterprise.html (default true)
  -tls
     Whether to enable TLS for incoming HTTP requests at -httpListenAddr (aka https). -tlsCertFile and -tlsKeyFile must be set if -tls is set
  -tlsCertFile string
     Path to file with TLS certificate if -tls is set. Prefer ECDSA certs instead of RSA certs as RSA certs are slower. The provided certificate file is automatically re-read every second, so it can be dynamically updated
  -tlsCipherSuites array
     Optional list of TLS cipher suites for incoming requests over HTTPS if -tls is set. See the list of supported cipher suites at https://pkg.go.dev/crypto/tls#pkg-constants
     Supports an array of values separated by comma or specified via multiple flags.
  -tlsKeyFile string
     Path to file with TLS key if -tls is set. The provided key file is automatically re-read every second, so it can be dynamically updated
  -tlsMinVersion string
     Optional minimum TLS version to use for incoming requests over HTTPS if -tls is set. Supported values: TLS10, TLS11, TLS12, TLS13
  -unittestFile array
     Path to the unit test files. When set, vmalert starts in unit test mode and performs only tests on configured files.
     Examples:
      -unittestFile="./unittest/testdata/test1.yaml,./unittest/testdata/test2.yaml".
     See more information here https://docs.victoriametrics.com/vmalert.html#unit-testing-for-rules.
  -version
     Show VictoriaMetrics version
```
{% endraw  %}

### Hot config reload

`vmalert` supports "hot" config reload via the following methods:

* send SIGHUP signal to `vmalert` process;
* send GET request to `/-/reload` endpoint;
* configure `-configCheckInterval` flag for periodic reload
  on config change.

### URL params

To set additional URL params for `datasource.url`, `remoteWrite.url` or `remoteRead.url`
just add them in address: `-datasource.url=http://localhost:8428?nocache=1`.

To set additional URL params for specific [group of rules](#Groups) modify
the `params` group:

```yaml
groups:
  - name: TestGroup
    params:
      denyPartialResponse: ["true"]
      extra_label: ["env=dev"]
```

Please note, `params` are used only for executing rules expressions (requests to `datasource.url`).
If there would be a conflict between URL params set in `datasource.url` flag and params in group definition
the latter will have higher priority.

### Notifier configuration file

Notifier also supports configuration via file specified with flag `notifier.config`:

```
./bin/vmalert -rule=app/vmalert/config/testdata/rules.good.rules \
  -datasource.url=http://localhost:8428 \
  -notifier.config=app/vmalert/notifier/testdata/consul.good.yaml
```

The configuration file allows to configure static notifiers, discover notifiers via
[Consul](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#consul_sd_config)
and [DNS](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#dns_sd_config):
For example:

```yaml
static_configs:
  - targets:
      - localhost:9093
      - localhost:9095

consul_sd_configs:
  - server: localhost:8500
    services:
      - alertmanager

dns_sd_configs:
  - names:
      - my.domain.com
    type: 'A'
    port: 9093
```

The list of configured or discovered Notifiers can be explored via [UI](#Web).
If Alertmanager runs in cluster mode then all its URLs needs to be available during discovery
to ensure [high availability](https://github.com/prometheus/alertmanager#high-availability).

The configuration file [specification](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/app/vmalert/notifier/config.go)
is the following:

```yaml
# Per-target Notifier timeout when pushing alerts.
[ timeout: <duration> | default = 10s ]

# Prefix for the HTTP path alerts are pushed to.
[ path_prefix: <path> | default = / ]

# Configures the protocol scheme used for requests.
[ scheme: <scheme> | default = http ]

# Sets the `Authorization` header on every request with the
# configured username and password.
# password and password_file are mutually exclusive.
basic_auth:
  [ username: <string> ]
  [ password: <string> ]
  [ password_file: <string> ]

# Optional `Authorization` header configuration.
authorization:
  # Sets the authentication type.
  [ type: <string> | default: Bearer ]
  # Sets the credentials. It is mutually exclusive with
  # `credentials_file`.
  [ credentials: <secret> ]
  # Sets the credentials to the credentials read from the configured file.
  # It is mutually exclusive with `credentials`.
  [ credentials_file: <filename> ]

# Configures the scrape request's TLS settings.
# see https://prometheus.io/docs/prometheus/latest/configuration/configuration/#tls_config
tls_config:
  [ <tls_config> ]

# Configures Bearer authentication token via string
bearer_token: <string>
# or by passing path to the file with token.
bearer_token_file: <string>

# Configures OAuth 2.0 authentication
# see https://prometheus.io/docs/prometheus/latest/configuration/configuration/#oauth2
oauth2:
  [ <oauth2_config> ]
  
# Optional list of HTTP headers in form `header-name: value`
# applied for all requests to notifiers
# For example:
#  headers:
#    - "CustomHeader: foo"
#    - "CustomHeader2: bar"
headers:
  [ <string>, ...]

# List of labeled statically configured Notifiers.
#
# Each list of targets may be additionally instructed with
# authorization params. Target's authorization params will
# inherit params from global authorization params if there
# are no conflicts.
static_configs:
  [ - targets: ]
      [ - '<host>' ]
      [ oauth2 ]
      [ basic_auth ]
      [ authorization ]
      [ tls_config ]
      [ bearer_token ]
      [ bearer_token_file ]
      [ headers ]

# List of Consul service discovery configurations.
# See https://prometheus.io/docs/prometheus/latest/configuration/configuration/#consul_sd_config
consul_sd_configs:
  [ - <consul_sd_config> ... ]

# List of DNS service discovery configurations.
# See https://prometheus.io/docs/prometheus/latest/configuration/configuration/#dns_sd_config
dns_sd_configs:
  [ - <dns_sd_config> ... ]

# List of relabel configurations for entities discovered via service discovery.
# Supports the same relabeling features as the rest of VictoriaMetrics components.
# See https://docs.victoriametrics.com/vmagent.html#relabeling
relabel_configs:
  [ - <relabel_config> ... ]

# List of relabel configurations for alert labels sent via Notifier.
# Supports the same relabeling features as the rest of VictoriaMetrics components.
# See https://docs.victoriametrics.com/vmagent.html#relabeling
alert_relabel_configs:
  [ - <relabel_config> ... ]
```

The configuration file can be [hot-reloaded](#hot-config-reload).

## Contributing

`vmalert` is mostly designed and built by VictoriaMetrics community.
Feel free to share your experience and ideas for improving this
software. Please keep simplicity as the main priority.

## How to build from sources

It is recommended using
[binary releases](https://github.com/VictoriaMetrics/VictoriaMetrics/releases)

* `vmalert` is located in `vmutils-*` archives there.

### Docker image

You can build `vmalert` docker image from source and push it to your own docker repository.
Run the following commands from the root folder of [the repository](https://github.com/VictoriaMetrics/VictoriaMetrics):
```console
make package-vmalert
docker tag victoria-metrics/vmalert:version my-repo:my-version-name
docker push my-repo:my-version-name
```

To run the built image in `victoria-metrics-k8s-stack` or `VMAlert` CR object apply the following config change:

```yaml
kind: VMAlert
spec:
  image:
    repository: my-repo
    tag: my-version-name
```

### Development build

1. [Install Go](https://golang.org/doc/install). The minimum supported version is Go 1.19.
2. Run `make vmalert` from the root folder of [the repository](https://github.com/VictoriaMetrics/VictoriaMetrics).
   It builds `vmalert` binary and puts it into the `bin` folder.

### Production build

1. [Install docker](https://docs.docker.com/install/).
2. Run `make vmalert-prod` from the root folder of [the repository](https://github.com/VictoriaMetrics/VictoriaMetrics).
   It builds `vmalert-prod` binary and puts it into the `bin` folder.

### ARM build

ARM build may run on Raspberry Pi or on [energy-efficient ARM servers](https://blog.cloudflare.com/arm-takes-wing/).

### Development ARM build

1. [Install Go](https://golang.org/doc/install). The minimum supported version is Go 1.19.
2. Run `make vmalert-linux-arm` or `make vmalert-linux-arm64` from the root folder of [the repository](https://github.com/VictoriaMetrics/VictoriaMetrics).
   It builds `vmalert-linux-arm` or `vmalert-linux-arm64` binary respectively and puts it into the `bin` folder.

### Production ARM build

1. [Install docker](https://docs.docker.com/install/).
2. Run `make vmalert-linux-arm-prod` or `make vmalert-linux-arm64-prod` from the root folder of [the repository](https://github.com/VictoriaMetrics/VictoriaMetrics).
   It builds `vmalert-linux-arm-prod` or `vmalert-linux-arm64-prod` binary respectively and puts it into the `bin` folder.