app/vmselect/graphite: add /tags/<tag_name> handler for Graphite Tags API

README.md

@@ -206,6 +206,7 @@ or [an alternative dashboard for VictoriaMetrics cluster](https://grafana.com/gr
       - `metrics/expand` - expands Graphite metrics. See [these docs](https://graphite-api.readthedocs.io/en/latest/api.html#metrics-expand).
       - `metrics/index.json` - returns all the metric names. See [these docs](https://graphite-api.readthedocs.io/en/latest/api.html#metrics-index-json).
       - `tags` - returns tag names. See [these docs](https://graphite.readthedocs.io/en/stable/tags.html#exploring-tags).
+      - `tags/<tag_name>` - returns tag values for the given `<tag_name>`. See [these docs](https://graphite.readthedocs.io/en/stable/tags.html#exploring-tags).
 
 * URL for time series deletion: `http://<vmselect>:8481/delete/<accountID>/prometheus/api/v1/admin/tsdb/delete_series?match[]=<timeseries_selector_for_delete>`.
   Note that the `delete_series` handler should be used only in exceptional cases such as deletion of accidentally ingested incorrect time series. It shouldn't

app/vmselect/graphite/tag_values_response.qtpl

@@ -0,0 +1,21 @@
+{% stripspace %}
+
+Tags generates response for /tags/<tag_name> handler
+See https://graphite.readthedocs.io/en/stable/tags.html#exploring-tags
+{% func TagValuesResponse(isPartial bool, tagName string, tagValues []string) %}
+{
+	"tag":{%q= tagName %},
+	{% if isPartial %}"is_partial":true,{% endif %}
+	"values":[
+	{% for i, value := range tagValues %}
+		{
+			"count":1,
+			"value":{%q= value %}
+		}
+		{% if i+1 < len(tagValues) %},{% endif %}
+	{% endfor %}
+	]
+}
+{% endfunc %}
+
+{% endstripspace %}

app/vmselect/graphite/tag_values_response.qtpl.go

@@ -0,0 +1,83 @@
+// Code generated by qtc from "tag_values_response.qtpl". DO NOT EDIT.
+// See https://github.com/valyala/quicktemplate for details.
+
+// Tags generates response for /tags/<tag_name> handlerSee https://graphite.readthedocs.io/en/stable/tags.html#exploring-tags
+
+//line app/vmselect/graphite/tag_values_response.qtpl:5
+package graphite
+
+//line app/vmselect/graphite/tag_values_response.qtpl:5
+import (
+	qtio422016 "io"
+
+	qt422016 "github.com/valyala/quicktemplate"
+)
+
+//line app/vmselect/graphite/tag_values_response.qtpl:5
+var (
+	_ = qtio422016.Copy
+	_ = qt422016.AcquireByteBuffer
+)
+
+//line app/vmselect/graphite/tag_values_response.qtpl:5
+func StreamTagValuesResponse(qw422016 *qt422016.Writer, isPartial bool, tagName string, tagValues []string) {
+//line app/vmselect/graphite/tag_values_response.qtpl:5
+	qw422016.N().S(`{"tag":`)
+//line app/vmselect/graphite/tag_values_response.qtpl:7
+	qw422016.N().Q(tagName)
+//line app/vmselect/graphite/tag_values_response.qtpl:7
+	qw422016.N().S(`,`)
+//line app/vmselect/graphite/tag_values_response.qtpl:8
+	if isPartial {
+//line app/vmselect/graphite/tag_values_response.qtpl:8
+		qw422016.N().S(`"is_partial":true,`)
+//line app/vmselect/graphite/tag_values_response.qtpl:8
+	}
+//line app/vmselect/graphite/tag_values_response.qtpl:8
+	qw422016.N().S(`"values":[`)
+//line app/vmselect/graphite/tag_values_response.qtpl:10
+	for i, value := range tagValues {
+//line app/vmselect/graphite/tag_values_response.qtpl:10
+		qw422016.N().S(`{"count":1,"value":`)
+//line app/vmselect/graphite/tag_values_response.qtpl:13
+		qw422016.N().Q(value)
+//line app/vmselect/graphite/tag_values_response.qtpl:13
+		qw422016.N().S(`}`)
+//line app/vmselect/graphite/tag_values_response.qtpl:15
+		if i+1 < len(tagValues) {
+//line app/vmselect/graphite/tag_values_response.qtpl:15
+			qw422016.N().S(`,`)
+//line app/vmselect/graphite/tag_values_response.qtpl:15
+		}
+//line app/vmselect/graphite/tag_values_response.qtpl:16
+	}
+//line app/vmselect/graphite/tag_values_response.qtpl:16
+	qw422016.N().S(`]}`)
+//line app/vmselect/graphite/tag_values_response.qtpl:19
+}
+
+//line app/vmselect/graphite/tag_values_response.qtpl:19
+func WriteTagValuesResponse(qq422016 qtio422016.Writer, isPartial bool, tagName string, tagValues []string) {
+//line app/vmselect/graphite/tag_values_response.qtpl:19
+	qw422016 := qt422016.AcquireWriter(qq422016)
+//line app/vmselect/graphite/tag_values_response.qtpl:19
+	StreamTagValuesResponse(qw422016, isPartial, tagName, tagValues)
+//line app/vmselect/graphite/tag_values_response.qtpl:19
+	qt422016.ReleaseWriter(qw422016)
+//line app/vmselect/graphite/tag_values_response.qtpl:19
+}
+
+//line app/vmselect/graphite/tag_values_response.qtpl:19
+func TagValuesResponse(isPartial bool, tagName string, tagValues []string) string {
+//line app/vmselect/graphite/tag_values_response.qtpl:19
+	qb422016 := qt422016.AcquireByteBuffer()
+//line app/vmselect/graphite/tag_values_response.qtpl:19
+	WriteTagValuesResponse(qb422016, isPartial, tagName, tagValues)
+//line app/vmselect/graphite/tag_values_response.qtpl:19
+	qs422016 := string(qb422016.B)
+//line app/vmselect/graphite/tag_values_response.qtpl:19
+	qt422016.ReleaseByteBuffer(qb422016)
+//line app/vmselect/graphite/tag_values_response.qtpl:19
+	return qs422016
+//line app/vmselect/graphite/tag_values_response.qtpl:19
+}

app/vmselect/graphite/tags_api.go

@@ -14,7 +14,49 @@ import (
 	"github.com/VictoriaMetrics/metrics"
 )
 
-// TagsHandler implements handler for /tags endpoint.
+// TagValuesHandler implements /tags/<tag_name> endpoint from Graphite Tags API.
+//
+// See https://graphite.readthedocs.io/en/stable/tags.html#exploring-tags
+func TagValuesHandler(startTime time.Time, at *auth.Token, tagName string, w http.ResponseWriter, r *http.Request) error {
+	deadline := searchutils.GetDeadlineForQuery(r, startTime)
+	if err := r.ParseForm(); err != nil {
+		return fmt.Errorf("cannot parse form values: %w", err)
+	}
+	limit := 0
+	if limitStr := r.FormValue("limit"); len(limitStr) > 0 {
+		var err error
+		limit, err = strconv.Atoi(limitStr)
+		if err != nil {
+			return fmt.Errorf("cannot parse limit=%q: %w", limit, err)
+		}
+	}
+	denyPartialResponse := searchutils.GetDenyPartialResponse(r)
+	tagValues, isPartial, err := netstorage.GetGraphiteTagValues(at, denyPartialResponse, tagName, limit, deadline)
+	if err != nil {
+		return err
+	}
+	filter := r.FormValue("filter")
+	if len(filter) > 0 {
+		tagValues, err = applyRegexpFilter(filter, tagValues)
+		if err != nil {
+			return err
+		}
+	}
+
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	bw := bufferedwriter.Get(w)
+	defer bufferedwriter.Put(bw)
+	WriteTagValuesResponse(bw, isPartial, tagName, tagValues)
+	if err := bw.Flush(); err != nil {
+		return err
+	}
+	tagValuesDuration.UpdateDuration(startTime)
+	return nil
+}
+
+var tagValuesDuration = metrics.NewSummary(`vm_request_duration_seconds{path="/tags/<tag_name>"}`)
+
+// TagsHandler implements /tags endpoint from Graphite Tags API.
 //
 // See https://graphite.readthedocs.io/en/stable/tags.html#exploring-tags
 func TagsHandler(startTime time.Time, at *auth.Token, w http.ResponseWriter, r *http.Request) error {
@@ -37,20 +79,10 @@ func TagsHandler(startTime time.Time, at *auth.Token, w http.ResponseWriter, r *
 	}
 	filter := r.FormValue("filter")
 	if len(filter) > 0 {
-		// Anchor filter regexp to the beginning of the string as Graphite does.
+		labels, err = applyRegexpFilter(filter, labels)
-		// See https://github.com/graphite-project/graphite-web/blob/3ad279df5cb90b211953e39161df416e54a84948/webapp/graphite/tags/localdatabase.py#L157
-		filter = "^(?:" + filter + ")"
-		re, err := regexp.Compile(filter)
 		if err != nil {
-			return fmt.Errorf("cannot parse regexp filter=%q: %w", filter, err)
+			return err
 		}
-		dst := labels[:0]
-		for _, label := range labels {
-			if re.MatchString(label) {
-				dst = append(dst, label)
-			}
-		}
-		labels = dst
 	}
 
 	w.Header().Set("Content-Type", "application/json; charset=utf-8")
@@ -65,3 +97,20 @@ func TagsHandler(startTime time.Time, at *auth.Token, w http.ResponseWriter, r *
 }
 
 var tagsDuration = metrics.NewSummary(`vm_request_duration_seconds{path="/tags"}`)
+
+func applyRegexpFilter(filter string, ss []string) ([]string, error) {
+	// Anchor filter regexp to the beginning of the string as Graphite does.
+	// See https://github.com/graphite-project/graphite-web/blob/3ad279df5cb90b211953e39161df416e54a84948/webapp/graphite/tags/localdatabase.py#L157
+	filter = "^(?:" + filter + ")"
+	re, err := regexp.Compile(filter)
+	if err != nil {
+		return nil, fmt.Errorf("cannot parse regexp filter=%q: %w", filter, err)
+	}
+	dst := ss[:0]
+	for _, s := range ss {
+		if re.MatchString(s) {
+			dst = append(dst, s)
+		}
+	}
+	return dst, nil
+}

app/vmselect/main.go

@@ -209,6 +209,16 @@ func selectHandler(startTime time.Time, w http.ResponseWriter, r *http.Request,
 			return true
 		}
 	}
+	if strings.HasPrefix(p.Suffix, "graphite/tags/") {
+		tagName := p.Suffix[len("graphite/tags/"):]
+		graphiteTagValuesRequests.Inc()
+		if err := graphite.TagValuesHandler(startTime, at, tagName, w, r); err != nil {
+			graphiteTagValuesErrors.Inc()
+			httpserver.Errorf(w, r, "error in %q: %s", r.URL.Path, err)
+			return true
+		}
+		return true
+	}
 
 	switch p.Suffix {
 	case "prometheus/api/v1/query":
@@ -450,6 +460,9 @@ var (
 	graphiteTagsRequests = metrics.NewCounter(`vm_http_requests_total{path="/select/{}/graphite/tags"}`)
 	graphiteTagsErrors   = metrics.NewCounter(`vm_http_request_errors_total{path="/select/{}/graphite/tags"}`)
 
+	graphiteTagValuesRequests = metrics.NewCounter(`vm_http_requests_total{path="/select/{}/graphite/tags/<tag_name>"}`)
+	graphiteTagValuesErrors   = metrics.NewCounter(`vm_http_request_errors_total{path="/select/{}/graphite/tags/<tag_name>"}`)
+
 	rulesRequests    = metrics.NewCounter(`vm_http_requests_total{path="/select/{}/prometheus/api/v1/rules"}`)
 	alertsRequests   = metrics.NewCounter(`vm_http_requests_total{path="/select/{}/prometheus/api/v1/alerts"}`)
 	metadataRequests = metrics.NewCounter(`vm_http_requests_total{path="/select/{}/prometheus/api/v1/metadata"}`)

app/vmselect/netstorage/netstorage.go

@@ -713,6 +713,24 @@ func GetLabelValuesOnTimeRange(at *auth.Token, denyPartialResponse bool, labelNa
 	return labelValues, isPartial, nil
 }
 
+// GetGraphiteTagValues returns tag values for the given tagName until the given deadline.
+func GetGraphiteTagValues(at *auth.Token, denyPartialResponse bool, tagName string, limit int, deadline searchutils.Deadline) ([]string, bool, error) {
+	if deadline.Exceeded() {
+		return nil, false, fmt.Errorf("timeout exceeded before starting the query processing: %s", deadline.String())
+	}
+	if tagName == "name" {
+		tagName = ""
+	}
+	tagValues, isPartial, err := GetLabelValues(at, denyPartialResponse, tagName, deadline)
+	if err != nil {
+		return nil, false, err
+	}
+	if limit < len(tagValues) {
+		tagValues = tagValues[:limit]
+	}
+	return tagValues, isPartial, nil
+}
+
 // GetLabelValues returns label values for the given labelName
 // until the given deadline.
 func GetLabelValues(at *auth.Token, denyPartialResponse bool, labelName string, deadline searchutils.Deadline) ([]string, bool, error) {

docs/Cluster-VictoriaMetrics.md

@@ -206,6 +206,7 @@ or [an alternative dashboard for VictoriaMetrics cluster](https://grafana.com/gr
       - `metrics/expand` - expands Graphite metrics. See [these docs](https://graphite-api.readthedocs.io/en/latest/api.html#metrics-expand).
       - `metrics/index.json` - returns all the metric names. See [these docs](https://graphite-api.readthedocs.io/en/latest/api.html#metrics-index-json).
       - `tags` - returns tag names. See [these docs](https://graphite.readthedocs.io/en/stable/tags.html#exploring-tags).
+      - `tags/<tag_name>` - returns tag values for the given `<tag_name>`. See [these docs](https://graphite.readthedocs.io/en/stable/tags.html#exploring-tags).
 
 * URL for time series deletion: `http://<vmselect>:8481/delete/<accountID>/prometheus/api/v1/admin/tsdb/delete_series?match[]=<timeseries_selector_for_delete>`.
   Note that the `delete_series` handler should be used only in exceptional cases such as deletion of accidentally ingested incorrect time series. It shouldn't

docs/Single-server-VictoriaMetrics.md

@@ -549,6 +549,7 @@ VictoriaMetrics supports the following handlers from [Graphite Tags API](https:/
 * [/tags/tagSeries](https://graphite.readthedocs.io/en/stable/tags.html#adding-series-to-the-tagdb)
 * [/tags/tagMultiSeries](https://graphite.readthedocs.io/en/stable/tags.html#adding-series-to-the-tagdb)
 * [/tags](https://graphite.readthedocs.io/en/stable/tags.html#exploring-tags)
+* [/tags/tag_name](https://graphite.readthedocs.io/en/stable/tags.html#exploring-tags)
 
 
 ### How to build from sources