Add Google Analytics reporting in place of existing custom reporting (#2015)

Replacing the older analytics with a new Google Analytics based mechanism.

pkg/tracker/tracker.go

@@ -0,0 +1,101 @@
+/*
+Copyright 2021 The Fission Authors.
+
+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,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+package tracker
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"net/http"
+	"net/url"
+	"os"
+	"time"
+
+	uuid "github.com/satori/go.uuid"
+)
+
+const HTTP_TIMEOUT = 5 * time.Second
+const GA_API_URL = "https://www.google-analytics.com/collect"
+const GA_TRACKING_ID = "GA_TRACKING_ID"
+
+var Tracker *tracker
+
+type (
+	tracker struct {
+		gaPropertyID string
+		cid          string
+	}
+	Event struct {
+		Category string
+		Action   string
+		Label    string
+		Value    string
+	}
+)
+
+func init() {
+	Tracker = &tracker{gaPropertyID: os.Getenv(GA_TRACKING_ID), cid: uuid.NewV4().String()}
+}
+
+func (t *tracker) SendEvent(e Event) error {
+	if t.gaPropertyID == "" {
+		return errors.New("tracker.SendEvent: GA_TRACKING_ID env not set")
+	}
+
+	if e.Action == "" || e.Category == "" {
+		return errors.New("tracker.SendEvent: category and action are required")
+	}
+
+	v := url.Values{
+		"v":   {"1"},
+		"tid": {t.gaPropertyID},
+		"cid": {t.cid},
+		"t":   {"event"},
+		"ec":  {e.Category},
+		"ea":  {e.Action},
+	}
+
+	if e.Label != "" {
+		v.Add("el", e.Label)
+	}
+
+	if e.Value != "" {
+		v.Add("ev", e.Value)
+	}
+
+	buf := bytes.NewBufferString(v.Encode())
+	req, err := http.NewRequest("POST", GA_API_URL, buf)
+	req.Header.Add("Content-Type", "application/x-www-form-urlencoded")
+	req.Header.Add("User-Agent", "ga-tracker/1.0")
+	if err != nil {
+		return err
+	}
+	ctx, cancel := context.WithTimeout(req.Context(), HTTP_TIMEOUT)
+	defer cancel()
+
+	req = req.WithContext(ctx)
+
+	client := http.DefaultClient
+	resp, err := client.Do(req)
+	if err != nil {
+		return err
+	}
+	if resp.StatusCode != http.StatusOK {
+		return errors.New("tracker.SendEvent: analytics response status not ok")
+	}
+	defer resp.Body.Close()
+	return err
+}