app/vmselect/graphite: add /tags/autoComplete/tags handler from Graphite Tags API

See https://graphite.readthedocs.io/en/stable/tags.html#auto-complete-support

README.md

@@ -551,6 +551,7 @@ VictoriaMetrics supports the following handlers from [Graphite Tags API](https:/
 * [/tags](https://graphite.readthedocs.io/en/stable/tags.html#exploring-tags)
 * [/tags/tag_name](https://graphite.readthedocs.io/en/stable/tags.html#exploring-tags)
 * [/tags/findSeries](https://graphite.readthedocs.io/en/stable/tags.html#exploring-tags)
+* [/tags/autoComplete/tags](https://graphite.readthedocs.io/en/stable/tags.html#auto-complete-support)
 
 
 ### How to build from sources

app/vmselect/graphite/metrics_api.go

@@ -84,10 +84,7 @@ func MetricsFindHandler(startTime time.Time, w http.ResponseWriter, r *http.Requ
 	}
 	paths = deduplicatePaths(paths, delimiter)
 	sortPaths(paths, delimiter)
-	contentType := "application/json; charset=utf-8"
-	if jsonp != "" {
-		contentType = "text/javascript; charset=utf-8"
-	}
+	contentType := getContentType(jsonp)
 	w.Header().Set("Content-Type", contentType)
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
@@ -166,10 +163,7 @@ func MetricsExpandHandler(startTime time.Time, w http.ResponseWriter, r *http.Re
 		}
 		m[query] = paths
 	}
-	contentType := "application/json; charset=utf-8"
-	if jsonp != "" {
-		contentType = "text/javascript; charset=utf-8"
-	}
+	contentType := getContentType(jsonp)
 	w.Header().Set("Content-Type", contentType)
 	if groupByExpr {
 		for _, paths := range m {
@@ -215,10 +209,7 @@ func MetricsIndexHandler(startTime time.Time, w http.ResponseWriter, r *http.Req
 	if err != nil {
 		return fmt.Errorf(`cannot obtain metric names: %w`, err)
 	}
-	contentType := "application/json; charset=utf-8"
-	if jsonp != "" {
-		contentType = "text/javascript; charset=utf-8"
-	}
+	contentType := getContentType(jsonp)
 	w.Header().Set("Content-Type", contentType)
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
@@ -417,3 +408,10 @@ var regexpCache = make(map[regexpCacheKey]*regexpCacheEntry)
 var regexpCacheLock sync.Mutex
 
 const maxRegexpCacheSize = 10000
+
+func getContentType(jsonp string) string {
+	if jsonp == "" {
+		return "application/json; charset=utf-8"
+	}
+	return "text/javascript; charset=utf-8"
+}

app/vmselect/graphite/tags_api.go

@@ -3,6 +3,7 @@ package graphite
 import (
 	"fmt"
 	"net/http"
+	"regexp"
 	"sort"
 	"strconv"
 	"strings"
@@ -15,6 +16,90 @@ import (
 	"github.com/VictoriaMetrics/metrics"
 )
 
+// TagsAutoCompleteTagsHandler implements /tags/autoComplete/tags endpoint from Graphite Tags API.
+//
+// See https://graphite.readthedocs.io/en/stable/tags.html#auto-complete-support
+func TagsAutoCompleteTagsHandler(startTime time.Time, 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, err := getInt(r, "limit")
+	if err != nil {
+		return err
+	}
+	if limit <= 0 {
+		// Use limit=100 by default. See https://graphite.readthedocs.io/en/stable/tags.html#auto-complete-support
+		limit = 100
+	}
+	tagPrefix := r.FormValue("tagPrefix")
+	exprs := r.Form["expr"]
+	var labels []string
+	if len(exprs) == 0 {
+		// Fast path: there are no `expr` filters.
+
+		// Escape special chars in tagPrefix as Graphite does.
+		// See https://github.com/graphite-project/graphite-web/blob/3ad279df5cb90b211953e39161df416e54a84948/webapp/graphite/tags/base.py#L181
+		filter := regexp.QuoteMeta(tagPrefix)
+		labels, err = netstorage.GetGraphiteTags(filter, limit, deadline)
+		if err != nil {
+			return err
+		}
+	} else {
+		// Slow path: use netstorage.SearchMetricNames for applying `expr` filters.
+		tfs, err := exprsToTagFilters(exprs)
+		if err != nil {
+			return err
+		}
+		ct := time.Now().UnixNano() / 1e6
+		sq := &storage.SearchQuery{
+			MinTimestamp: 0,
+			MaxTimestamp: ct,
+			TagFilterss:  [][]storage.TagFilter{tfs},
+		}
+		mns, err := netstorage.SearchMetricNames(sq, deadline)
+		if err != nil {
+			return fmt.Errorf("cannot fetch metric names for %q: %w", sq, err)
+		}
+		m := make(map[string]struct{})
+		for _, mn := range mns {
+			m["name"] = struct{}{}
+			for _, tag := range mn.Tags {
+				m[string(tag.Key)] = struct{}{}
+			}
+		}
+		if len(tagPrefix) > 0 {
+			for label := range m {
+				if !strings.HasPrefix(label, tagPrefix) {
+					delete(m, label)
+				}
+			}
+		}
+		labels = make([]string, 0, len(m))
+		for label := range m {
+			labels = append(labels, label)
+		}
+		sort.Strings(labels)
+		if limit > 0 && limit < len(labels) {
+			labels = labels[:limit]
+		}
+	}
+
+	jsonp := r.FormValue("jsonp")
+	contentType := getContentType(jsonp)
+	w.Header().Set("Content-Type", contentType)
+	bw := bufferedwriter.Get(w)
+	defer bufferedwriter.Put(bw)
+	WriteTagsAutoCompleteTagsResponse(bw, labels, jsonp)
+	if err := bw.Flush(); err != nil {
+		return err
+	}
+	tagsAutoCompleteTagsDuration.UpdateDuration(startTime)
+	return nil
+}
+
+var tagsAutoCompleteTagsDuration = metrics.NewSummary(`vm_request_duration_seconds{path="/tags/autoComplete/tags"}`)
+
 // TagsFindSeriesHandler implements /tags/findSeries endpoint from Graphite Tags API.
 //
 // See https://graphite.readthedocs.io/en/stable/tags.html#exploring-tags
@@ -31,18 +116,10 @@ func TagsFindSeriesHandler(startTime time.Time, w http.ResponseWriter, r *http.R
 	if len(exprs) == 0 {
 		return fmt.Errorf("expecting at least one `expr` query arg")
 	}
-
-	// Convert exprs to []storage.TagFilter
-	tfs := make([]storage.TagFilter, 0, len(exprs))
-	for _, expr := range exprs {
-		tf, err := parseFilterExpr(expr)
-		if err != nil {
-			return fmt.Errorf("cannot parse `expr` query arg: %w", err)
-		}
-		tfs = append(tfs, *tf)
+	tfs, err := exprsToTagFilters(exprs)
+	if err != nil {
+		return err
 	}
-
-	// Send the request to storage
 	ct := time.Now().UnixNano() / 1e6
 	sq := &storage.SearchQuery{
 		MinTimestamp: 0,
@@ -167,6 +244,18 @@ func getInt(r *http.Request, argName string) (int, error) {
 	return n, nil
 }
 
+func exprsToTagFilters(exprs []string) ([]storage.TagFilter, error) {
+	tfs := make([]storage.TagFilter, 0, len(exprs))
+	for _, expr := range exprs {
+		tf, err := parseFilterExpr(expr)
+		if err != nil {
+			return nil, fmt.Errorf("cannot parse `expr` query arg: %w", err)
+		}
+		tfs = append(tfs, *tf)
+	}
+	return tfs, nil
+}
+
 func parseFilterExpr(s string) (*storage.TagFilter, error) {
 	n := strings.Index(s, "=")
 	if n < 0 {

app/vmselect/graphite/tags_autocomplete_tags_response.qtpl

@@ -0,0 +1,16 @@
+{% stripspace %}
+
+TagsAutoCompleteTagsResponse generates response for /tags/autoComplete/tags handler in Graphite Tags API.
+See https://graphite.readthedocs.io/en/stable/tags.html#auto-complete-support
+{% func TagsAutoCompleteTagsResponse(labels []string, jsonp string) %}
+	{% if jsonp != "" %}{%s= jsonp %}({% endif %}
+	[
+		{% for i, label := range labels %}
+			{%q= label %}
+			{% if i+1 < len(labels) %},{% endif %}
+		{% endfor %}
+	]
+	{% if jsonp != "" %}){% endif %}
+{% endfunc %}
+
+{% endstripspace %}

app/vmselect/graphite/tags_autocomplete_tags_response.qtpl.go

@@ -0,0 +1,81 @@
+// Code generated by qtc from "tags_autocomplete_tags_response.qtpl". DO NOT EDIT.
+// See https://github.com/valyala/quicktemplate for details.
+
+// TagsAutoCompleteTagsResponse generates response for /tags/autoComplete/tags handler in Graphite Tags API.See https://graphite.readthedocs.io/en/stable/tags.html#auto-complete-support
+
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:5
+package graphite
+
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:5
+import (
+	qtio422016 "io"
+
+	qt422016 "github.com/valyala/quicktemplate"
+)
+
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:5
+var (
+	_ = qtio422016.Copy
+	_ = qt422016.AcquireByteBuffer
+)
+
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:5
+func StreamTagsAutoCompleteTagsResponse(qw422016 *qt422016.Writer, labels []string, jsonp string) {
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:6
+	if jsonp != "" {
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:6
+		qw422016.N().S(jsonp)
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:6
+		qw422016.N().S(`(`)
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:6
+	}
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:6
+	qw422016.N().S(`[`)
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:8
+	for i, label := range labels {
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:9
+		qw422016.N().Q(label)
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:10
+		if i+1 < len(labels) {
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:10
+			qw422016.N().S(`,`)
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:10
+		}
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:11
+	}
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:11
+	qw422016.N().S(`]`)
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:13
+	if jsonp != "" {
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:13
+		qw422016.N().S(`)`)
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:13
+	}
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:14
+}
+
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:14
+func WriteTagsAutoCompleteTagsResponse(qq422016 qtio422016.Writer, labels []string, jsonp string) {
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:14
+	qw422016 := qt422016.AcquireWriter(qq422016)
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:14
+	StreamTagsAutoCompleteTagsResponse(qw422016, labels, jsonp)
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:14
+	qt422016.ReleaseWriter(qw422016)
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:14
+}
+
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:14
+func TagsAutoCompleteTagsResponse(labels []string, jsonp string) string {
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:14
+	qb422016 := qt422016.AcquireByteBuffer()
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:14
+	WriteTagsAutoCompleteTagsResponse(qb422016, labels, jsonp)
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:14
+	qs422016 := string(qb422016.B)
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:14
+	qt422016.ReleaseByteBuffer(qb422016)
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:14
+	return qs422016
+//line app/vmselect/graphite/tags_autocomplete_tags_response.qtpl:14
+}

app/vmselect/main.go

@@ -132,7 +132,7 @@ func RequestHandler(w http.ResponseWriter, r *http.Request) bool {
 			return true
 		}
 	}
-	if strings.HasPrefix(path, "/tags/") && path != "/tags/findSeries" {
+	if strings.HasPrefix(path, "/tags/") && !isGraphiteTagsPath(path) {
 		tagName := r.URL.Path[len("/tags/"):]
 		graphiteTagValuesRequests.Inc()
 		if err := graphite.TagValuesHandler(startTime, tagName, w, r); err != nil {
@@ -285,6 +285,15 @@ func RequestHandler(w http.ResponseWriter, r *http.Request) bool {
 			return true
 		}
 		return true
+	case "/tags/autoComplete/tags":
+		graphiteTagsAutoCompleteTagsRequests.Inc()
+		httpserver.EnableCORS(w, r)
+		if err := graphite.TagsAutoCompleteTagsHandler(startTime, w, r); err != nil {
+			graphiteTagsAutoCompleteTagsErrors.Inc()
+			httpserver.Errorf(w, r, "error in %q: %s", r.URL.Path, err)
+			return true
+		}
+		return true
 	case "/api/v1/rules":
 		// Return dumb placeholder
 		rulesRequests.Inc()
@@ -322,6 +331,18 @@ func RequestHandler(w http.ResponseWriter, r *http.Request) bool {
 	}
 }
 
+func isGraphiteTagsPath(path string) bool {
+	switch path {
+	// See https://graphite.readthedocs.io/en/stable/tags.html for a list of Graphite Tags API paths.
+	// Do not include `/tags/<tag_name>` here, since this will fool the caller.
+	case "/tags/tagSeries", "/tags/tagMultiSeries", "/tags/findSeries",
+		"/tags/autoComplete/tags", "/tags/autoComplete/values", "/tags/delSeries":
+		return true
+	default:
+		return false
+	}
+}
+
 func sendPrometheusError(w http.ResponseWriter, r *http.Request, err error) {
 	logger.Warnf("error in %q: %s", r.RequestURI, err)
 
@@ -395,6 +416,9 @@ var (
 	graphiteTagsFindSeriesRequests = metrics.NewCounter(`vm_http_requests_total{path="/tags/findSeries"}`)
 	graphiteTagsFindSeriesErrors   = metrics.NewCounter(`vm_http_request_errors_total{path="/tags/findSeries"}`)
 
+	graphiteTagsAutoCompleteTagsRequests = metrics.NewCounter(`vm_http_requests_total{path="/tags/autoComplete/tags"}`)
+	graphiteTagsAutoCompleteTagsErrors   = metrics.NewCounter(`vm_http_request_errors_total{path="/tags/autoComplete/tags"}`)
+
 	rulesRequests    = metrics.NewCounter(`vm_http_requests_total{path="/api/v1/rules"}`)
 	alertsRequests   = metrics.NewCounter(`vm_http_requests_total{path="/api/v1/alerts"}`)
 	metadataRequests = metrics.NewCounter(`vm_http_requests_total{path="/api/v1/metadata"}`)

app/vmselect/netstorage/netstorage.go

@@ -493,6 +493,7 @@ func GetGraphiteTags(filter string, limit int, deadline searchutils.Deadline) ([
 	for i := range labels {
 		if labels[i] == "__name__" {
 			labels[i] = "name"
+			sort.Strings(labels)
 			break
 		}
 	}

docs/Single-server-VictoriaMetrics.md

@@ -551,6 +551,7 @@ VictoriaMetrics supports the following handlers from [Graphite Tags API](https:/
 * [/tags](https://graphite.readthedocs.io/en/stable/tags.html#exploring-tags)
 * [/tags/tag_name](https://graphite.readthedocs.io/en/stable/tags.html#exploring-tags)
 * [/tags/findSeries](https://graphite.readthedocs.io/en/stable/tags.html#exploring-tags)
+* [/tags/autoComplete/tags](https://graphite.readthedocs.io/en/stable/tags.html#auto-complete-support)
 
 
 ### How to build from sources