Add util class to support to add annotations to Grafana (#378)

* Add util class for adding annotation to grafana

tests/pkg/metrics/annotation_util.go

@@ -0,0 +1,147 @@
+// Copyright 2018 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 metrics
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"net"
+	"net/http"
+	"net/url"
+	"os"
+	"path"
+	"sync"
+)
+
+//Client request grafana API on a set of resource paths.
+type client struct {
+	// base is the root URL for all invocations of the client
+	baseUrl url.URL
+	client  *http.Client
+}
+
+//Annotation is a specification of the desired behavior of adding annotation
+type Annotation struct {
+	AnnotationOptions
+	Text                string   `json:"text"`
+	Tags                []string `json:"tags"`
+	TimestampInMilliSec int64    `json:"time"`
+}
+
+//AnnotationOptions is the query options to a standard REST list call.
+type AnnotationOptions struct {
+	DashboardId int   `json:"dashboardId, omitempty"`
+	PanelId     int   `json:"panelId, omitempty"`
+	IsRegin     bool  `json:"isRegion, omitempty"`
+	TimeEnd     int64 `json:"timeEnd, omitempty"`
+}
+
+//NewClient creats a new grafanaClient. This client performs rest functions
+//such as Get, Post on specified paths.
+func NewClient(grafanaUrl string, userName string, password string, prometheusExporterPort int) (*client, error) {
+	u, err := url.Parse(grafanaUrl)
+	if err != nil {
+		return nil, err
+	}
+
+	initFunc(prometheusExporterPort)
+	u.User = url.UserPassword(userName, password)
+	return &client{
+		baseUrl: *u,
+		client:  &http.Client{},
+	}, nil
+}
+
+func (annotation Annotation) getBody() ([]byte, error) {
+	body, err := json.Marshal(annotation)
+	if err != nil {
+		return nil, err
+	}
+
+	return body, nil
+}
+
+var (
+	initedOnce        sync.Once
+	counterMetric     prometheus.Counter
+	annotationSubPath = "api/annotations"
+)
+
+//initFunc is called with sync.Once, we use sync.Once to keep the thread safe.
+func initFunc(port int) {
+	initedOnce.Do(func() {
+		counterMetric = initErrorMetric()
+		prometheus.MustRegister(counterMetric)
+		mux := http.NewServeMux()
+
+		l, err := net.Listen("tcp", fmt.Sprintf(":%d", port))
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "listening port %d failed, %v", port, err)
+			panic(err)
+		}
+
+		mux.Handle("/metrics", promhttp.Handler())
+		srv := &http.Server{Handler: mux}
+		go srv.Serve(l)
+	})
+}
+
+func initErrorMetric() prometheus.Counter {
+	return prometheus.NewCounter(prometheus.CounterOpts{
+		Name:        "error_count",
+		Help:        "record error count",
+		ConstLabels: map[string]string{"fortest": "true"},
+	})
+}
+
+//IncreErrorCountWithAnno increments the errorcount by 1,
+//and add the annotation to grafanan.
+func (cli *client) AddAnnotation(annotation Annotation) error {
+	body, err := annotation.getBody()
+	if err != nil {
+		return fmt.Errorf("create request body faield, %v", err)
+	}
+
+	req, err := http.NewRequest("POST", cli.getAnnotationPath(), bytes.NewBuffer(body))
+	if err != nil {
+		return fmt.Errorf("create request failed, %v", err)
+	}
+
+	req.Header.Add("Accept", "application/json, text/plain, */*")
+	req.Header.Add("Content-Type", "application/json;charset=UTF-8")
+	resp, error := cli.client.Do(req)
+	if error != nil {
+		return fmt.Errorf("add annotation faield, %v", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("add annotation faield, statusCode=%v", resp.Status)
+	}
+
+	return nil
+}
+
+func (cli *client) IncrErrorCount() {
+	counterMetric.Inc()
+}
+
+func (cli *client) getAnnotationPath() string {
+	u := cli.baseUrl
+	u.Path = path.Join(cli.baseUrl.Path, annotationSubPath)
+	return u.String()
+}

tests/pkg/metrics/annotation_util_test.go

@@ -0,0 +1,46 @@
+// Copyright 2018 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 metrics
+
+import (
+	"encoding/json"
+	"fmt"
+	"github.com/onsi/gomega"
+	"testing"
+)
+
+func TestAnnotationGetBody(t *testing.T) {
+	tags := []string{"1", "2", "3"}
+
+	options := AnnotationOptions{
+		DashboardId: 1,
+		PanelId:     2,
+	}
+
+	annotation := Annotation{
+		Tags:                tags,
+		TimestampInMilliSec: 1,
+		Text:                "abc",
+	}
+
+	annotation.AnnotationOptions = options
+
+	b, _ := annotation.getBody()
+	re := make(map[string]interface{})
+	json.Unmarshal(b, &re)
+
+	g := gomega.NewGomegaWithT(t)
+	g.Expect(fmt.Sprintf("%v", re["dashboardId"])).To(gomega.Equal(fmt.Sprintf("%v", 1)))
+	g.Expect(re["text"]).To(gomega.Equal("abc"))
+	g.Expect(re["time"]).To(gomega.Equal(float64(1)))
+}