*: add query metric http api (#1957)

conf/config.toml

@@ -54,6 +54,12 @@ interval = "15s"
 ## prometheus pushgateway address, leaves it empty will disable prometheus.
 address = ""
 
+[pd-server]
+## the metric storage is the cluster metric storage. This is use for query metric data.
+## Currently we use prometheus as metric storage, we may use PD/TiKV as metric storage later.
+## For usability, recommended to temporarily set it to the prometheus address, eg: http://127.0.0.1:9090
+metric-storage = ""
+
 [schedule]
 max-merge-region-size = 20
 max-merge-region-keys = 200000

server/api/api.raml

@@ -1299,3 +1299,98 @@ types:
           description: The input is invalid.
         500:
           description: PD server failed to proceed the request.
+
+/metric:
+  description: Query metric.
+  /query:
+    get:
+      description: Query instant metric api.
+      queryParameters:
+        query:
+          description: promQL query statement.
+          type: string
+        time?:
+          description: Evaluation timestamp, such as 2019-11-22T20:10:51.781Z.
+          type: string
+        timeout?:
+          description: Evaluation timeout, such as 15s.
+          type: string
+      responses:
+        200:
+          body:
+            application/json:
+              properties:
+                data: Metric data
+        500:
+          description: PD server failed to proceed the request.
+    post:
+      description: Query instant metric api.
+      body:
+        application/json:
+          properties:
+            query:
+              description: promQL query statement.
+              type: string
+            time?:
+              description: Evaluation timestamp, such as 2019-11-22T20:10:51.781Z.
+              type: string
+            timeout?:
+              description: Evaluation timeout, such as 15s.
+              type: string
+      responses:
+        200:
+          body:
+            application/json:
+              properties:
+                data: Metric data
+        500:
+          description: PD server failed to proceed the request.
+  /query_range:
+    get:
+      description: Query range metric api.
+      queryParameters:
+        query:
+          description: promQL query statement.
+          type: string
+        start:
+          description: Evaluation start timestamp, such as 2019-11-22T20:10:51.781Z.
+          type: string
+        end:
+          description: Evaluation end timestamp, such as 2019-11-22T20:10:51.781Z.
+          type: string
+        timeout?:
+          description: Evaluation timeout, such as 15s.
+          type: string
+      responses:
+        200:
+          body:
+            application/json:
+              properties:
+                data: Metric data
+        500:
+          description: PD server failed to proceed the request.
+    post:
+      description: Query range metric api.
+      body:
+        application/json:
+          properties:
+            query:
+              description: promQL query statement.
+              type: string
+            start:
+              description: Evaluation start timestamp, such as 2019-11-22T20:10:51.781Z.
+              type: string
+            end:
+              description: Evaluation end timestamp, such as 2019-11-22T20:10:51.781Z.
+              type: string
+            timeout?:
+              description: Evaluation timeout, such as 15s.
+              type: string
+      responses:
+        200:
+          body:
+            application/json:
+              properties:
+                data: Metric data
+        500:
+          description: PD server failed to proceed the request.

server/api/config_test.go

@@ -63,12 +63,21 @@ func (s *testConfigSuite) TestConfigAll(c *C) {
 	err = postJSON(addr, postData)
 	c.Assert(err, IsNil)
 
+	l = map[string]interface{}{
+		"metric-storage": "http://127.0.0.1:9090",
+	}
+	postData, err = json.Marshal(l)
+	c.Assert(err, IsNil)
+	err = postJSON(addr, postData)
+	c.Assert(err, IsNil)
+
 	newCfg := &config.Config{}
 	err = readJSON(addr, newCfg)
 	c.Assert(err, IsNil)
 	cfg.Replication.MaxReplicas = 5
 	cfg.Replication.LocationLabels = []string{"zone", "rack"}
 	cfg.Schedule.RegionScheduleLimit = 10
+	cfg.PDServerCfg.MetricStorage = "http://127.0.0.1:9090"
 	c.Assert(cfg, DeepEquals, newCfg)
 }
 

server/api/metric.go

@@ -0,0 +1,54 @@
+// Copyright 2019 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package api
+
+import (
+	"fmt"
+	"net/http"
+	"net/url"
+	"strings"
+
+	"github.com/pingcap/pd/server"
+)
+
+type queryMetric struct {
+	s *server.Server
+}
+
+func newQueryMetric(s *server.Server) *queryMetric {
+	return &queryMetric{s: s}
+}
+
+func (h *queryMetric) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	metricAddr := h.s.GetConfig().PDServerCfg.MetricStorage
+	if metricAddr == "" {
+		http.Error(w, "metric storage doesn't set", http.StatusInternalServerError)
+		return
+	}
+	u, err := url.Parse(metricAddr)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	switch u.Scheme {
+	case "http", "https":
+		// Replace the pd path with the prometheus http API path.
+		r.URL.Path = strings.Replace(r.URL.Path, "pd/api/v1/metric", "api/v1", 1)
+		newCustomReverseProxies([]url.URL{*u}).ServeHTTP(w, r)
+	default:
+		// TODO: Support read data by self after support store metric data in PD/TiKV.
+		http.Error(w, fmt.Sprintf("schema of metric storage address is no supported, address: %v", metricAddr), http.StatusInternalServerError)
+	}
+}

server/api/router.go

@@ -144,6 +144,9 @@ func createRouter(prefix string, svr *server.Server) *mux.Router {
 	rootRouter.Handle("/api/v1/health", newHealthHandler(svr, rd)).Methods("GET")
 	rootRouter.Handle("/api/v1/diagnose", newDiagnoseHandler(svr, rd)).Methods("GET")
 	rootRouter.HandleFunc("/api/v1/ping", func(w http.ResponseWriter, r *http.Request) {}).Methods("GET")
+	// metric query use to query metric data, the protocol is compatible with prometheus.
+	rootRouter.Handle("/api/v1/metric/query", newQueryMetric(svr)).Methods("GET", "POST")
+	rootRouter.Handle("/api/v1/metric/query_range", newQueryMetric(svr)).Methods("GET", "POST")
 
 	// Deprecated
 	rootRouter.Handle("/health", newHealthHandler(svr, rd)).Methods("GET")

server/config/config.go

@@ -887,6 +887,9 @@ type PDServerConfig struct {
 	// KeyType is option to specify the type of keys.
 	// There are some types supported: ["table", "raw", "txn"], default: "table"
 	KeyType string `toml:"key-type" json:"key-type"`
+	// MetricStorage is the cluster metric storage.
+	// Currently we use prometheus as metric storage, we may use PD/TiKV as metric storage later.
+	MetricStorage string `toml:"metric-storage" json:"metric-storage"`
 }
 
 func (c *PDServerConfig) adjust(meta *configMetaData) error {

server/config/config_test.go

@@ -106,6 +106,9 @@ func (s *testConfigSuite) TestAdjust(c *C) {
 name = ""
 lease = 0
 
+[pd-server]
+metric-storage = "http://127.0.0.1:9090"
+
 [schedule]
 max-merge-region-size = 0
 enable-one-way-merge = true
@@ -129,6 +132,7 @@ leader-schedule-limit = 0
 	// When undefined, use default values.
 	c.Assert(cfg.PreVote, IsTrue)
 	c.Assert(cfg.Schedule.MaxMergeRegionKeys, Equals, uint64(defaultMaxMergeRegionKeys))
+	c.Assert(cfg.PDServerCfg.MetricStorage, Equals, "http://127.0.0.1:9090")
 
 	// Check undefined config fields
 	cfgData = `