vmagent: expose metrics for tracking config state (#3375)

Expose `vm_relabel_config_*` and `vm_promscrape_config_*` metrics
for tracking relabel and scrape configuration hot-reloads.

https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3345
Signed-off-by: hagen1778 <roman@victoriametrics.com>

Signed-off-by: hagen1778 <roman@victoriametrics.com>

app/vmagent/remotewrite/remotewrite.go

@@ -13,6 +13,7 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bloomfilter"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/cgroup"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/flagutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/memory"
@@ -139,6 +140,8 @@ func Init() {
 		logger.Fatalf("cannot load relabel configs: %s", err)
 	}
 	allRelabelConfigs.Store(rcs)
+	configSuccess.Set(1)
+	configTimestamp.Set(fasttime.UnixTimestamp())
 
 	if len(*remoteWriteURLs) > 0 {
 		rwctxsDefault = newRemoteWriteCtxs(nil, *remoteWriteURLs)
@@ -154,18 +157,31 @@ func Init() {
 			case <-stopCh:
 				return
 			}
+			configReloads.Inc()
 			logger.Infof("SIGHUP received; reloading relabel configs pointed by -remoteWrite.relabelConfig and -remoteWrite.urlRelabelConfig")
 			rcs, err := loadRelabelConfigs()
 			if err != nil {
+				configReloadErrors.Inc()
+				configSuccess.Set(0)
 				logger.Errorf("cannot reload relabel configs; preserving the previous configs; error: %s", err)
 				continue
 			}
+
 			allRelabelConfigs.Store(rcs)
+			configSuccess.Set(1)
+			configTimestamp.Set(fasttime.UnixTimestamp())
 			logger.Infof("Successfully reloaded relabel configs")
 		}
 	}()
 }
 
+var (
+	configReloads      = metrics.NewCounter(`vm_relabel_config_reloads_total`)
+	configReloadErrors = metrics.NewCounter(`vm_relabel_config_reloads_errors_total`)
+	configSuccess      = metrics.NewCounter(`vm_relabel_config_last_reload_successful`)
+	configTimestamp    = metrics.NewCounter(`vm_relabel_config_last_reload_success_timestamp_seconds`)
+)
+
 func newRemoteWriteCtxs(at *auth.Token, urls []string) []*remoteWriteCtx {
 	if len(urls) == 0 {
 		logger.Panicf("BUG: urls must be non-empty")

deployment/docker/alerts-vmagent.yml

@@ -120,3 +120,15 @@ groups:
           summary: "Instance {{ $labels.instance }} reached 90% of the limit"
           description: "Max series limit set via -remoteWrite.maxDailySeries flag is close to reaching the max value. 
             Then samples for new time series will be dropped instead of sending them to remote storage systems."
+
+      - alert: ConfigurationReloadFailure
+        expr: |
+          vm_promscrape_config_last_reload_successful != 1
+          or
+          vm_relabel_config_last_reload_successful != 1
+        labels:
+          severity: warning
+        annotations:
+          summary: "Configuration reload failed for vmagent instance {{ $labels.instance }}"
+          description: "Configuration hot-reload failed for vmagent on instance {{ $labels.instance }}.
+          Check vmagent's logs for detailed error message."

docs/CHANGELOG.md

@@ -27,6 +27,7 @@ The following tip changes can be tested by building VictoriaMetrics components f
 * FEATURE: [vmui](https://docs.victoriametrics.com/#vmui): add copy button to row on Table view. The button copies row in MetricQL format. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/2815).
 * FEATURE: [vmui](https://docs.victoriametrics.com/#vmui): add the ability to "stick" a tooltip on the chart by clicking on a data point. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3321) and [this pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/3376)
 * FEATURE: [vmalert](https://docs.victoriametrics.com/vmalert.html): add default alert list for vmalert's metrics. See [alerts-vmalert.yml](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/deployment/docker/alerts-vmalert.yml).
+* FEATURE: [vmagent](https://docs.victoriametrics.com/vmagent.html): expose `vm_relabel_config_*` and `vm_promscrape_config_*` metrics for tracking relabel and scrape configuration hot-reloads. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3345).
 
 * BUGFIX: [MetricsQL](https://docs.victoriametrics.com/MetricsQL.html): properly return an empty result from [limit_offset](https://docs.victoriametrics.com/MetricsQL.html#limit_offset) if the `offset` arg exceeds the number of inner time series. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3312).
 * BUGFIX: [vmagent](https://docs.victoriametrics.com/vmagent.html): properly discover GCE zones when `filter` option is set at [gce_sd_configs](https://docs.victoriametrics.com/sd_configs.html#gce_sd_configs). See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3202).

lib/promscrape/scraper.go

@@ -4,12 +4,13 @@ import (
 	"bytes"
 	"flag"
 	"fmt"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/auth"
 	"io"
 	"sync"
 	"sync/atomic"
 	"time"
 
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/auth"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/procutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
@@ -112,6 +113,9 @@ func runScraper(configFile string, pushData func(at *auth.Token, wr *prompbmarsh
 	configData.Store(&marshaledData)
 	cfg.mustStart()
 
+	configSuccess.Set(1)
+	configTimestamp.Set(fasttime.UnixTimestamp())
+
 	scs := newScrapeConfigs(pushData, globalStopCh)
 	scs.add("azure_sd_configs", *azure.SDCheckInterval, func(cfg *Config, swsPrev []*ScrapeWork) []*ScrapeWork { return cfg.getAzureSDScrapeWork(swsPrev) })
 	scs.add("consul_sd_configs", *consul.SDCheckInterval, func(cfg *Config, swsPrev []*ScrapeWork) []*ScrapeWork { return cfg.getConsulSDScrapeWork(swsPrev) })
@@ -143,6 +147,8 @@ func runScraper(configFile string, pushData func(at *auth.Token, wr *prompbmarsh
 			logger.Infof("SIGHUP received; reloading Prometheus configs from %q", configFile)
 			cfgNew, dataNew, err := loadConfig(configFile)
 			if err != nil {
+				configReloadErrors.Inc()
+				configSuccess.Set(0)
 				logger.Errorf("cannot read %q on SIGHUP: %s; continuing with the previous config", configFile, err)
 				goto waitForChans
 			}
@@ -158,6 +164,8 @@ func runScraper(configFile string, pushData func(at *auth.Token, wr *prompbmarsh
 		case <-tickerCh:
 			cfgNew, dataNew, err := loadConfig(configFile)
 			if err != nil {
+				configReloadErrors.Inc()
+				configSuccess.Set(0)
 				logger.Errorf("cannot read %q: %s; continuing with the previous config", configFile, err)
 				goto waitForChans
 			}
@@ -180,10 +188,17 @@ func runScraper(configFile string, pushData func(at *auth.Token, wr *prompbmarsh
 		}
 		logger.Infof("found changes in %q; applying these changes", configFile)
 		configReloads.Inc()
+		configSuccess.Set(1)
+		configTimestamp.Set(fasttime.UnixTimestamp())
 	}
 }
 
-var configReloads = metrics.NewCounter(`vm_promscrape_config_reloads_total`)
+var (
+	configReloads      = metrics.NewCounter(`vm_promscrape_config_reloads_total`)
+	configReloadErrors = metrics.NewCounter(`vm_promscrape_config_reloads_errors_total`)
+	configSuccess      = metrics.NewCounter(`vm_promscrape_config_last_reload_successful`)
+	configTimestamp    = metrics.NewCounter(`vm_promscrape_config_last_reload_success_timestamp_seconds`)
+)
 
 type scrapeConfigs struct {
 	pushData     func(at *auth.Token, wr *prompbmarshal.WriteRequest)