app/{vminsert,vmagent}: follow-up after 53a63c6c4c

Extend /api/v1/import/prometheus with the support for Pushgateway way of specifying additional labels.

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1415

README.md

@@ -1048,7 +1048,8 @@ Time series data can be imported into VictoriaMetrics via any supported data ing
 * `/api/v1/import/native` for importing data obtained from [/api/v1/export/native](#how-to-export-data-in-native-format).
   See [these docs](#how-to-import-data-in-native-format) for details.
 * `/api/v1/import/csv` for importing arbitrary CSV data. See [these docs](#how-to-import-csv-data) for details.
-* `/api/v1/import/prometheus` for importing data in Prometheus exposition format. See [these docs](#how-to-import-data-in-prometheus-exposition-format) for details.
+* `/api/v1/import/prometheus` for importing data in Prometheus exposition format and in [Pushgateway format](https://github.com/prometheus/pushgateway#url).
+  See [these docs](#how-to-import-data-in-prometheus-exposition-format) for details.
 
 ### How to import data in JSON line format
 
@@ -1153,9 +1154,11 @@ Note that it could be required to flush response cache after importing historica
 
 ### How to import data in Prometheus exposition format
 
-VictoriaMetrics accepts data in [Prometheus exposition format](https://github.com/prometheus/docs/blob/master/content/docs/instrumenting/exposition_formats.md#text-based-format)
+VictoriaMetrics accepts data in [Prometheus exposition format](https://github.com/prometheus/docs/blob/master/content/docs/instrumenting/exposition_formats.md#text-based-format),
-and in [OpenMetrics format](https://github.com/OpenObservability/OpenMetrics/blob/master/specification/OpenMetrics.md)
+in [OpenMetrics format](https://github.com/OpenObservability/OpenMetrics/blob/master/specification/OpenMetrics.md)
-via `/api/v1/import/prometheus` path. For example, the following line imports a single line in Prometheus exposition format into VictoriaMetrics:
+and in [Pushgateway format](https://github.com/prometheus/pushgateway#url) via `/api/v1/import/prometheus` path.
+
+For example, the following command imports a single line in Prometheus exposition format into VictoriaMetrics:
 
 <div class="with-copy" markdown="1">
 
@@ -1181,6 +1184,16 @@ It should return something like the following:
 {"metric":{"__name__":"foo","bar":"baz"},"values":[123],"timestamps":[1594370496905]}
 ```
 
+The following command imports a single metric via [Pushgateway format](https://github.com/prometheus/pushgateway#url) with `{job="my_app",instance="host123"}` labels:
+
+<div class="with-copy" markdown="1">
+
+```console
+curl -d 'metric{label="abc"} 123' -X POST 'http://localhost:8428/api/v1/import/prometheus/metrics/job/my_app/instance/host123'
+```
+
+</div>
+
 Pass `Content-Encoding: gzip` HTTP request header to `/api/v1/import/prometheus` for importing gzipped data:
 
 <div class="with-copy" markdown="1">
@@ -1192,8 +1205,8 @@ curl -X POST -H 'Content-Encoding: gzip' http://destination-victoriametrics:8428
 
 </div>
 
-Extra labels may be added to all the imported metrics by passing `extra_label=name=value` query args.
+Extra labels may be added to all the imported metrics either via [Pushgateway format](https://github.com/prometheus/pushgateway#url)
-For example, `/api/v1/import/prometheus?extra_label=foo=bar` would add `{foo="bar"}` label to all the imported metrics.
+or by passing `extra_label=name=value` query args. For example, `/api/v1/import/prometheus?extra_label=foo=bar` would add `{foo="bar"}` label to all the imported metrics.
 
 If timestamp is missing in `<metric> <value> <timestamp>` Prometheus exposition format line, then the current timestamp is used during data ingestion.
 It can be overridden by passing unix timestamp in *milliseconds* via `timestamp` query arg. For example, `/api/v1/import/prometheus?timestamp=1594370496905`.

app/vmagent/main.go

@@ -20,7 +20,6 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/opentsdbhttp"
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/prometheusimport"
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/promremotewrite"
-	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/pushgateway"
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/remotewrite"
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/vmimport"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/auth"
@@ -218,6 +217,16 @@ func requestHandler(w http.ResponseWriter, r *http.Request) bool {
 	}
 
 	path := strings.Replace(r.URL.Path, "//", "/", -1)
+	if strings.HasPrefix(path, "/prometheus/api/v1/import/prometheus") || strings.HasPrefix(path, "/api/v1/import/prometheus") {
+		prometheusimportRequests.Inc()
+		if err := prometheusimport.InsertHandler(nil, r); err != nil {
+			prometheusimportErrors.Inc()
+			httpserver.Errorf(w, r, "%s", err)
+			return true
+		}
+		w.WriteHeader(http.StatusNoContent)
+		return true
+	}
 	if strings.HasPrefix(path, "datadog/") {
 		// Trim suffix from paths starting from /datadog/ in order to support legacy DataDog agent.
 		// See https://github.com/VictoriaMetrics/VictoriaMetrics/pull/2670
@@ -251,15 +260,6 @@ func requestHandler(w http.ResponseWriter, r *http.Request) bool {
 		}
 		w.WriteHeader(http.StatusNoContent)
 		return true
-	case "/prometheus/api/v1/import/prometheus", "/api/v1/import/prometheus":
-		prometheusimportRequests.Inc()
-		if err := prometheusimport.InsertHandler(nil, r); err != nil {
-			prometheusimportErrors.Inc()
-			httpserver.Errorf(w, r, "%s", err)
-			return true
-		}
-		w.WriteHeader(http.StatusNoContent)
-		return true
 	case "/prometheus/api/v1/import/native", "/api/v1/import/native":
 		nativeimportRequests.Inc()
 		if err := native.InsertHandler(nil, r); err != nil {
@@ -388,16 +388,6 @@ func requestHandler(w http.ResponseWriter, r *http.Request) bool {
 			staticServer.ServeHTTP(w, r)
 			return true
 		}
-		if strings.HasPrefix(r.URL.Path, "/api/v1/pushgateway") {
-			pushgatewayRequests.Inc()
-			if err := pushgateway.InsertHandler(nil, r); err != nil {
-				pushgatewayErrors.Inc()
-				httpserver.Errorf(w, r, "%s", err)
-				return true
-			}
-			w.WriteHeader(http.StatusNoContent)
-			return true
-		}
 		if remotewrite.MultitenancyEnabled() {
 			return processMultitenantRequest(w, r, path)
 		}
@@ -420,6 +410,16 @@ func processMultitenantRequest(w http.ResponseWriter, r *http.Request, path stri
 		httpserver.Errorf(w, r, "cannot obtain auth token: %s", err)
 		return true
 	}
+	if strings.HasPrefix(p.Suffix, "prometheus/api/v1/import/prometheus") {
+		prometheusimportRequests.Inc()
+		if err := prometheusimport.InsertHandler(at, r); err != nil {
+			prometheusimportErrors.Inc()
+			httpserver.Errorf(w, r, "%s", err)
+			return true
+		}
+		w.WriteHeader(http.StatusNoContent)
+		return true
+	}
 	if strings.HasPrefix(p.Suffix, "datadog/") {
 		// Trim suffix from paths starting from /datadog/ in order to support legacy DataDog agent.
 		// See https://github.com/VictoriaMetrics/VictoriaMetrics/pull/2670
@@ -453,15 +453,6 @@ func processMultitenantRequest(w http.ResponseWriter, r *http.Request, path stri
 		}
 		w.WriteHeader(http.StatusNoContent)
 		return true
-	case "prometheus/api/v1/import/prometheus":
-		prometheusimportRequests.Inc()
-		if err := prometheusimport.InsertHandler(at, r); err != nil {
-			prometheusimportErrors.Inc()
-			httpserver.Errorf(w, r, "%s", err)
-			return true
-		}
-		w.WriteHeader(http.StatusNoContent)
-		return true
 	case "prometheus/api/v1/import/native":
 		nativeimportRequests.Inc()
 		if err := native.InsertHandler(at, r); err != nil {
@@ -519,16 +510,6 @@ func processMultitenantRequest(w http.ResponseWriter, r *http.Request, path stri
 		fmt.Fprintf(w, `{}`)
 		return true
 	default:
-		if strings.HasPrefix(r.URL.Path, "/api/v1/pushgateway") {
-			pushgatewayRequests.Inc()
-			if err := pushgateway.InsertHandler(nil, r); err != nil {
-				pushgatewayErrors.Inc()
-				httpserver.Errorf(w, r, "%s", err)
-				return true
-			}
-			w.WriteHeader(http.StatusNoContent)
-			return true
-		}
 		httpserver.Errorf(w, r, "unsupported multitenant path suffix: %q", p.Suffix)
 		return true
 	}
@@ -547,9 +528,6 @@ var (
 	prometheusimportRequests = metrics.NewCounter(`vmagent_http_requests_total{path="/api/v1/import/prometheus", protocol="prometheusimport"}`)
 	prometheusimportErrors   = metrics.NewCounter(`vmagent_http_request_errors_total{path="/api/v1/import/prometheus", protocol="prometheusimport"}`)
 
-	pushgatewayRequests = metrics.NewCounter(`vmagent_http_requests_total{path="/api/v1/pushgateway", protocol="pushgateway"}`)
-	pushgatewayErrors   = metrics.NewCounter(`vmagent_http_request_errors_total{path="/api/v1/pushgateway", protocol="pushgateway"}`)
-
 	nativeimportRequests = metrics.NewCounter(`vmagent_http_requests_total{path="/api/v1/import/native", protocol="nativeimport"}`)
 	nativeimportErrors   = metrics.NewCounter(`vmagent_http_request_errors_total{path="/api/v1/import/native", protocol="nativeimport"}`)
 

app/vmagent/pushgateway/request_handler.go

@@ -1,127 +0,0 @@
-package pushgateway
-
-import (
-	"fmt"
-	"net/http"
-	"strings"
-
-	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/common"
-	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmagent/remotewrite"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/auth"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
-	parserCommon "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/common"
-	parser "github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/prometheus"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/tenantmetrics"
-	"github.com/VictoriaMetrics/VictoriaMetrics/lib/writeconcurrencylimiter"
-	"github.com/VictoriaMetrics/metrics"
-)
-
-var (
-	rowsInserted       = metrics.NewCounter(`vmagent_rows_inserted_total{type="pushgateway"}`)
-	rowsTenantInserted = tenantmetrics.NewCounterMap(`vmagent_tenant_inserted_rows_total{type="pushgateway"}`)
-	rowsPerInsert      = metrics.NewHistogram(`vmagent_rows_per_insert{type="pushgateway"}`)
-)
-
-// InsertHandler processes `/api/v1/pushgateway` request.
-func InsertHandler(at *auth.Token, req *http.Request) error {
-	// Pushgateway endpoint is of the style: /metrics/job/<JOB_NAME>{/<LABEL_NAME>/<LABEL_VALUE>}
-	// Source:https://github.com/prometheus/pushgateway#url
-	pushgatewayPath := strings.TrimSuffix(strings.Replace(req.URL.Path, "/api/v1/pushgateway", "", 1), "/")
-	pathLabels, err := extractLabelsFromPath(pushgatewayPath)
-	if err != nil {
-		return err
-	}
-	extraLabels, err := parserCommon.GetExtraLabels(req)
-	if err != nil {
-		return err
-	}
-	defaultTimestamp, err := parserCommon.GetTimestamp(req)
-	if err != nil {
-		return err
-	}
-	return writeconcurrencylimiter.Do(func() error {
-		isGzipped := req.Header.Get("Content-Encoding") == "gzip"
-		return parser.ParseStream(req.Body, defaultTimestamp, isGzipped, func(rows []parser.Row) error {
-			return insertRows(at, rows, append(pathLabels, extraLabels...))
-		}, nil)
-	})
-}
-
-func extractLabelsFromPath(pushgatewayPath string) ([]prompbmarshal.Label, error) {
-	// Parsing Pushgateway path which is of the style: /metrics/job/<JOB_NAME>{/<LABEL_NAME>/<LABEL_VALUE>}
-	// With an arbitrary number of /<LABEL_NAME>/<LABEL_VALUE> pairs
-	// Source:https://github.com/prometheus/pushgateway#url
-	var result []prompbmarshal.Label
-	if !strings.HasPrefix(pushgatewayPath, "/metrics/job/") {
-		return nil, fmt.Errorf("pushgateway endpoint format is incorrect. Expected /metrics/job/<JOB_NAME>{/<LABEL_NAME>/<LABEL_VALUE>}, got %q ", pushgatewayPath)
-	}
-	labelsString := strings.Replace(pushgatewayPath, "/metrics/job/", "", 1)
-	labelsSlice := strings.Split(labelsString, "/")
-	if len(labelsSlice) == 1 && labelsSlice[0] == "" {
-		return nil, fmt.Errorf("pushgateway path has to contain a job name after /job/. Expected /metrics/job/<JOB_NAME>{/<LABEL_NAME>/<LABEL_VALUE>}, got %q ", pushgatewayPath)
-	}
-
-	//The first value that comes after /metrics/job/JOB_NAME gives origin to a label with key "job" and value "JOB_NAME"
-	result = append(result, prompbmarshal.Label{
-		Name:  "job",
-		Value: labelsSlice[0],
-	})
-
-	// We expect the number of items to be odd.
-	// The first item is the job label and after that is key/value pairs
-	if len(labelsSlice)%2 == 0 {
-		return nil, fmt.Errorf("number of label key/pair passed via pushgateway endpoint format does not match")
-	}
-
-	// We start at 1, since index 0 was the job label value, and we jump every 2 - first item is the key, second is the value.
-	for i := 1; i < len(labelsSlice); i = i + 2 {
-		result = append(result, prompbmarshal.Label{
-			Name:  labelsSlice[i],
-			Value: labelsSlice[i+1],
-		})
-	}
-	return result, nil
-}
-
-func insertRows(at *auth.Token, rows []parser.Row, extraLabels []prompbmarshal.Label) error {
-	ctx := common.GetPushCtx()
-	defer common.PutPushCtx(ctx)
-
-	tssDst := ctx.WriteRequest.Timeseries[:0]
-	labels := ctx.Labels[:0]
-	samples := ctx.Samples[:0]
-	for i := range rows {
-		r := &rows[i]
-		labelsLen := len(labels)
-		labels = append(labels, prompbmarshal.Label{
-			Name:  "__name__",
-			Value: r.Metric,
-		})
-		for j := range r.Tags {
-			tag := &r.Tags[j]
-			labels = append(labels, prompbmarshal.Label{
-				Name:  tag.Key,
-				Value: tag.Value,
-			})
-		}
-		labels = append(labels, extraLabels...)
-		samples = append(samples, prompbmarshal.Sample{
-			Value:     r.Value,
-			Timestamp: r.Timestamp,
-		})
-		tssDst = append(tssDst, prompbmarshal.TimeSeries{
-			Labels:  labels[labelsLen:],
-			Samples: samples[len(samples)-1:],
-		})
-	}
-	ctx.WriteRequest.Timeseries = tssDst
-	ctx.Labels = labels
-	ctx.Samples = samples
-	remotewrite.Push(at, &ctx.WriteRequest)
-	rowsInserted.Add(len(rows))
-	if at != nil {
-		rowsTenantInserted.Get(at).Add(len(rows))
-	}
-	rowsPerInsert.Update(float64(len(rows)))
-	return nil
-}

app/vminsert/main.go

@@ -120,6 +120,16 @@ func RequestHandler(w http.ResponseWriter, r *http.Request) bool {
 		staticServer.ServeHTTP(w, r)
 		return true
 	}
+	if strings.HasPrefix(path, "/prometheus/api/v1/import/prometheus") || strings.HasPrefix(path, "/api/v1/import/prometheus") {
+		prometheusimportRequests.Inc()
+		if err := prometheusimport.InsertHandler(r); err != nil {
+			prometheusimportErrors.Inc()
+			httpserver.Errorf(w, r, "%s", err)
+			return true
+		}
+		w.WriteHeader(http.StatusNoContent)
+		return true
+	}
 	if strings.HasPrefix(path, "/datadog/") {
 		// Trim suffix from paths starting from /datadog/ in order to support legacy DataDog agent.
 		// See https://github.com/VictoriaMetrics/VictoriaMetrics/pull/2670
@@ -153,15 +163,6 @@ func RequestHandler(w http.ResponseWriter, r *http.Request) bool {
 		}
 		w.WriteHeader(http.StatusNoContent)
 		return true
-	case "/prometheus/api/v1/import/prometheus", "/api/v1/import/prometheus":
-		prometheusimportRequests.Inc()
-		if err := prometheusimport.InsertHandler(r); err != nil {
-			prometheusimportErrors.Inc()
-			httpserver.Errorf(w, r, "%s", err)
-			return true
-		}
-		w.WriteHeader(http.StatusNoContent)
-		return true
 	case "/prometheus/api/v1/import/native", "/api/v1/import/native":
 		nativeimportRequests.Inc()
 		if err := native.InsertHandler(r); err != nil {

docs/CHANGELOG.md

@@ -15,6 +15,7 @@ The following tip changes can be tested by building VictoriaMetrics components f
 
 ## tip
 
+* FEATURE: add support for [Pushgateway data import format](https://github.com/prometheus/pushgateway#url) via `/api/v1/import/prometheus` url. See [these docs](https://docs.victoriametrics.com/#how-to-import-data-in-prometheus-exposition-format) and [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1415). Thanks to @PerGon for [the intial implementation](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/3360).
 * FEATURE: [VictoriaMetrics cluster](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html): add `http://<vmselect>:8481/admin/tenants` API endpoint for returning a list of registered tenants. See [these docs](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html#url-format) for details.
 * FEATURE: [VictoriaMetrics enterprise](https://docs.victoriametrics.com/enterprise.html): add `-storageNode.filter` command-line flag for filtering the [discovered vmstorage nodes](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html#automatic-vmstorage-discovery) with arbitrary regular expressions. See [this feature request](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3353).
 * FEATURE: [MetricsQL](https://docs.victoriametrics.com/MetricsQL.html): allow using numeric values with `K`, `Ki`, `M`, `Mi`, `G`, `Gi`, `T` and `Ti` suffixes inside MetricsQL queries. For example `8Ki` equals to `8*1024`, while `8.2M` equals to `8.2*1000*1000`.

docs/Cluster-VictoriaMetrics.md

@@ -292,7 +292,7 @@ See [troubleshooting docs](https://docs.victoriametrics.com/Troubleshooting.html
     - `prometheus/api/v1/import` - for importing data obtained via `api/v1/export` at `vmselect` (see below).
     - `prometheus/api/v1/import/native` - for importing data obtained via `api/v1/export/native` on `vmselect` (see below).
     - `prometheus/api/v1/import/csv` - for importing arbitrary CSV data. See [these docs](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html#how-to-import-csv-data) for details.
-    - `prometheus/api/v1/import/prometheus` - for importing data in [Prometheus text exposition format](https://github.com/prometheus/docs/blob/master/content/docs/instrumenting/exposition_formats.md#text-based-format) and in [OpenMetrics format](https://github.com/OpenObservability/OpenMetrics/blob/master/specification/OpenMetrics.md). See [these docs](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html#how-to-import-data-in-prometheus-exposition-format) for details.
+    - `prometheus/api/v1/import/prometheus` - for importing data in [Prometheus text exposition format](https://github.com/prometheus/docs/blob/master/content/docs/instrumenting/exposition_formats.md#text-based-format) and in [OpenMetrics format](https://github.com/OpenObservability/OpenMetrics/blob/master/specification/OpenMetrics.md). This endpoint also supports [Pushgateway protocol](https://github.com/prometheus/pushgateway#url). See [these docs](https://docs.victoriametrics.com/Single-server-VictoriaMetrics.html#how-to-import-data-in-prometheus-exposition-format) for details.
 
 - URLs for [Prometheus querying API](https://prometheus.io/docs/prometheus/latest/querying/api/): `http://<vmselect>:8481/select/<accountID>/prometheus/<suffix>`, where:
   - `<accountID>` is an arbitrary number identifying data namespace for the query (aka tenant)

docs/Single-server-VictoriaMetrics.md

@@ -1052,7 +1052,8 @@ Time series data can be imported into VictoriaMetrics via any supported data ing
 * `/api/v1/import/native` for importing data obtained from [/api/v1/export/native](#how-to-export-data-in-native-format).
   See [these docs](#how-to-import-data-in-native-format) for details.
 * `/api/v1/import/csv` for importing arbitrary CSV data. See [these docs](#how-to-import-csv-data) for details.
-* `/api/v1/import/prometheus` for importing data in Prometheus exposition format. See [these docs](#how-to-import-data-in-prometheus-exposition-format) for details.
+* `/api/v1/import/prometheus` for importing data in Prometheus exposition format and in [Pushgateway format](https://github.com/prometheus/pushgateway#url).
+  See [these docs](#how-to-import-data-in-prometheus-exposition-format) for details.
 
 ### How to import data in JSON line format
 
@@ -1157,9 +1158,11 @@ Note that it could be required to flush response cache after importing historica
 
 ### How to import data in Prometheus exposition format
 
-VictoriaMetrics accepts data in [Prometheus exposition format](https://github.com/prometheus/docs/blob/master/content/docs/instrumenting/exposition_formats.md#text-based-format)
+VictoriaMetrics accepts data in [Prometheus exposition format](https://github.com/prometheus/docs/blob/master/content/docs/instrumenting/exposition_formats.md#text-based-format),
-and in [OpenMetrics format](https://github.com/OpenObservability/OpenMetrics/blob/master/specification/OpenMetrics.md)
+in [OpenMetrics format](https://github.com/OpenObservability/OpenMetrics/blob/master/specification/OpenMetrics.md)
-via `/api/v1/import/prometheus` path. For example, the following line imports a single line in Prometheus exposition format into VictoriaMetrics:
+and in [Pushgateway format](https://github.com/prometheus/pushgateway#url) via `/api/v1/import/prometheus` path.
+
+For example, the following command imports a single line in Prometheus exposition format into VictoriaMetrics:
 
 <div class="with-copy" markdown="1">
 
@@ -1185,6 +1188,16 @@ It should return something like the following:
 {"metric":{"__name__":"foo","bar":"baz"},"values":[123],"timestamps":[1594370496905]}
 ```
 
+The following command imports a single metric via [Pushgateway format](https://github.com/prometheus/pushgateway#url) with `{job="my_app",instance="host123"}` labels:
+
+<div class="with-copy" markdown="1">
+
+```console
+curl -d 'metric{label="abc"} 123' -X POST 'http://localhost:8428/api/v1/import/prometheus/metrics/job/my_app/instance/host123'
+```
+
+</div>
+
 Pass `Content-Encoding: gzip` HTTP request header to `/api/v1/import/prometheus` for importing gzipped data:
 
 <div class="with-copy" markdown="1">
@@ -1196,8 +1209,8 @@ curl -X POST -H 'Content-Encoding: gzip' http://destination-victoriametrics:8428
 
 </div>
 
-Extra labels may be added to all the imported metrics by passing `extra_label=name=value` query args.
+Extra labels may be added to all the imported metrics either via [Pushgateway format](https://github.com/prometheus/pushgateway#url)
-For example, `/api/v1/import/prometheus?extra_label=foo=bar` would add `{foo="bar"}` label to all the imported metrics.
+or by passing `extra_label=name=value` query args. For example, `/api/v1/import/prometheus?extra_label=foo=bar` would add `{foo="bar"}` label to all the imported metrics.
 
 If timestamp is missing in `<metric> <value> <timestamp>` Prometheus exposition format line, then the current timestamp is used during data ingestion.
 It can be overridden by passing unix timestamp in *milliseconds* via `timestamp` query arg. For example, `/api/v1/import/prometheus?timestamp=1594370496905`.

lib/protoparser/common/extra_labels.go

@@ -1,6 +1,7 @@
 package common
 
 import (
+	"encoding/base64"
 	"fmt"
 	"net/http"
 	"strings"
@@ -9,18 +10,74 @@ import (
 )
 
 // GetExtraLabels extracts name:value labels from `extra_label=name=value` query args from req.
+//
+// It also extracts Pushgateways-compatible extra labels from req.URL.Path
+// according to https://github.com/prometheus/pushgateway#url .
 func GetExtraLabels(req *http.Request) ([]prompbmarshal.Label, error) {
+	labels, err := getPushgatewayLabels(req.URL.Path)
+	if err != nil {
+		return nil, fmt.Errorf("cannot parse pushgateway-style labels from %q: %w", req.URL.Path, err)
+	}
 	q := req.URL.Query()
-	var result []prompbmarshal.Label
 	for _, label := range q["extra_label"] {
 		tmp := strings.SplitN(label, "=", 2)
 		if len(tmp) != 2 {
 			return nil, fmt.Errorf("`extra_label` query arg must have the format `name=value`; got %q", label)
 		}
-		result = append(result, prompbmarshal.Label{
+		labels = append(labels, prompbmarshal.Label{
 			Name:  tmp[0],
 			Value: tmp[1],
 		})
 	}
-	return result, nil
+	return labels, nil
+}
+
+func getPushgatewayLabels(path string) ([]prompbmarshal.Label, error) {
+	n := strings.Index(path, "/metrics/job")
+	if n < 0 {
+		return nil, nil
+	}
+	s := path[n+len("/metrics/"):]
+	if !strings.HasPrefix(s, "job/") && !strings.HasPrefix(s, "job@base64/") {
+		return nil, nil
+	}
+	labelsCount := (strings.Count(s, "/") + 1) / 2
+	labels := make([]prompbmarshal.Label, 0, labelsCount)
+	for len(s) > 0 {
+		n := strings.IndexByte(s, '/')
+		if n < 0 {
+			return nil, fmt.Errorf("missing value for label %q", s)
+		}
+		name := s[:n]
+		s = s[n+1:]
+		isBase64 := strings.HasSuffix(name, "@base64")
+		if isBase64 {
+			name = name[:len(name)-len("@base64")]
+		}
+		var value string
+		n = strings.IndexByte(s, '/')
+		if n < 0 {
+			value = s
+			s = ""
+		} else {
+			value = s[:n]
+			s = s[n+1:]
+		}
+		if isBase64 {
+			data, err := base64.URLEncoding.DecodeString(value)
+			if err != nil {
+				return nil, fmt.Errorf("cannot base64-decode value=%q for label=%q: %w", value, name, err)
+			}
+			value = string(data)
+		}
+		if len(value) == 0 {
+			// Skip labels with empty values
+			continue
+		}
+		labels = append(labels, prompbmarshal.Label{
+			Name:  name,
+			Value: value,
+		})
+	}
+	return labels, nil
 }

lib/protoparser/common/extra_labels_test.go

@@ -0,0 +1,91 @@
+package common
+
+import (
+	"fmt"
+	"net/http"
+	"sort"
+	"strings"
+	"testing"
+
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
+)
+
+func TestGetExtraLabelsSuccess(t *testing.T) {
+	f := func(requestURI, expectedLabels string) {
+		t.Helper()
+		fullURL := "http://fobar" + requestURI
+		req, err := http.NewRequest("GET", fullURL, nil)
+		if err != nil {
+			t.Fatalf("cannot parse %q: %s", fullURL, err)
+		}
+		extraLabels, err := GetExtraLabels(req)
+		if err != nil {
+			t.Fatalf("unexpected error: %s", err)
+		}
+		labelsStr := getLabelsString(extraLabels)
+		if labelsStr != expectedLabels {
+			t.Fatalf("unexpected labels;\ngot\n%s\nwant\n%s", labelsStr, expectedLabels)
+		}
+	}
+	f("", `{}`)
+	f("/foo/bar", `{}`)
+	f("/foo?extra_label=foo=bar", `{foo="bar"}`)
+	f("/foo?extra_label=a=x&extra_label=b=y", `{a="x",b="y"}`)
+	f("/metrics/job/foo", `{job="foo"}`)
+	f("/metrics/job/foo?extra_label=a=b", `{a="b",job="foo"}`)
+	f("/metrics/job/foo/b/bcd?extra_label=a=b&extra_label=qwe=rty", `{a="b",b="bcd",job="foo",qwe="rty"}`)
+	f("/metrics/job/titan/name/%CE%A0%CF%81%CE%BF%CE%BC%CE%B7%CE%B8%CE%B5%CF%8D%CF%82", `{job="titan",name="Προμηθεύς"}`)
+	f("/metrics/job/titan/name@base64/zqDPgc6_zrzOt864zrXPjc-C", `{job="titan",name="Προμηθεύς"}`)
+}
+
+func TestGetPushgatewayLabelsSuccess(t *testing.T) {
+	f := func(path, expectedLabels string) {
+		t.Helper()
+		labels, err := getPushgatewayLabels(path)
+		if err != nil {
+			t.Fatalf("unexpected error in getPushgatewayLabels(%q): %s", path, err)
+		}
+		labelsStr := getLabelsString(labels)
+		if labelsStr != expectedLabels {
+			t.Fatalf("unexpected labels returned from getPushgatewayLabels(%q);\ngot\n%s\nwant\n%s", path, labelsStr, expectedLabels)
+		}
+	}
+	f("", "{}")
+	f("/foo/bar", "{}")
+	f("/metrics/foo/bar", "{}")
+	f("/metrics/job", "{}")
+	f("/metrics/job@base64", "{}")
+	f("/metrics/job/", "{}")
+	f("/metrics/job/foo", `{job="foo"}`)
+	f("/foo/metrics/job/foo", `{job="foo"}`)
+	f("/api/v1/import/prometheus/metrics/job/foo", `{job="foo"}`)
+	f("/foo/metrics/job@base64/Zm9v", `{job="foo"}`)
+	f("/foo/metrics/job/x/a/foo/aaa/bar", `{a="foo",aaa="bar",job="x"}`)
+	f("/foo/metrics/job/x/a@base64/Zm9v", `{a="foo",job="x"}`)
+}
+
+func TestGetPushgatewayLabelsFailure(t *testing.T) {
+	f := func(path string) {
+		t.Helper()
+		labels, err := getPushgatewayLabels(path)
+		if err == nil {
+			labelsStr := getLabelsString(labels)
+			t.Fatalf("expecting non-nil error for getPushgatewayLabels(%q); got labels %s", path, labelsStr)
+		}
+	}
+	// missing bar value
+	f("/metrics/job/foo/bar")
+	// invalid base64 encoding for job
+	f("/metrics/job@base64/#$%")
+	// invalid base64 encoding for non-job label
+	f("/metrics/job/foo/bar@base64/#$%")
+}
+
+func getLabelsString(labels []prompbmarshal.Label) string {
+	a := make([]string, len(labels))
+	for i, label := range labels {
+		a[i] = fmt.Sprintf("%s=%q", label.Name, label.Value)
+	}
+	sort.Strings(a)
+	return "{" + strings.Join(a, ",") + "}"
+}