Add simple anonymous usage metrics (#1167)

This change reports total function call count to an analytics url once a day.

It's done behind the existing analytics flag.

charts/fission-all/templates/deployment.yaml

@@ -209,6 +209,13 @@ spec:
             value: {{ .Values.debugEnv | quote }}
           - name: TRACING_SAMPLING_RATE
             value: {{ .Values.traceSamplingRate | default "0.5" | quote }}
+{{ if .Values.analytics }}
+          - name: ANALYTICS_URL
+            value: "https://g.fission.sh/metrics"
+{{ else if .Values.analyticsNonHelmInstall }}
+          - name: ANALYTICS_URL
+            value: "https://g.fission.sh/metrics"
+{{ end }}
         readinessProbe:
           httpGet:
             path: "/router-healthz"

charts/fission-core/templates/deployment.yaml

@@ -211,6 +211,13 @@ spec:
             value: {{ .Values.routerRoundTripSvcAddressUpdateTimeout | default 30 | quote }}
           - name: DEBUG_ENV
             value: {{ .Values.debugEnv | quote }}
+{{ if .Values.analytics }}
+          - name: ANALYTICS_URL
+            value: "https://g.fission.sh/metrics"
+{{ else if .Values.analyticsNonHelmInstall }}
+          - name: ANALYTICS_URL
+            value: "https://g.fission.sh/metrics"
+{{ end }}
         readinessProbe:
           httpGet:
             path: "/router-healthz"

router/analytics.go

@@ -0,0 +1,61 @@
+package router
+
+import (
+	"bytes"
+	"encoding/json"
+	"net/http"
+	"os"
+	"sync/atomic"
+	"time"
+
+	"github.com/dchest/uniuri"
+)
+
+type (
+	Analytics struct {
+		id  string
+		url string
+	}
+	AnalyticsData struct {
+		id                string
+		FunctionCallCount uint64 `json:"FunctionCallCount"`
+	}
+)
+
+func MakeAnalytics(url string) *Analytics {
+
+	if len(url) == 0 {
+		url = os.Getenv("ANALYTICS_URL")
+		if len(url) == 0 {
+			return nil
+		}
+	}
+
+	a := &Analytics{
+		url: url,
+		id:  uniuri.NewLen(8),
+	}
+	go a.run()
+	return a
+}
+
+func (a *Analytics) gatherData() *AnalyticsData {
+	return &AnalyticsData{
+		FunctionCallCount: atomic.LoadUint64(&globalFunctionCallCount),
+	}
+}
+
+func (a *Analytics) run() {
+	ticker := time.NewTicker(24 * time.Hour)
+	for range ticker.C {
+		msg := a.gatherData()
+		msg.id = a.id
+
+		msgbytes, err := json.Marshal(*msg)
+		if err != nil {
+			continue
+		}
+
+		_, _ = http.Post(a.url, "application/json", bytes.NewReader(msgbytes))
+	}
+}

router/metrics.go

@@ -2,11 +2,14 @@ package router
 
 import (
 	"fmt"
+	"sync/atomic"
 	"time"
 
 	"github.com/prometheus/client_golang/prometheus"
 )
 
+var globalFunctionCallCount uint64
+
 type (
 	// functionLabels is the set of metrics labels that relate to
 	// functions.
@@ -116,6 +119,8 @@ func labelsToStrings(f *functionLabels, h *httpLabels) []string {
 }
 
 func functionCallCompleted(f *functionLabels, h *httpLabels, overhead, duration time.Duration, respSize int64) {
+	atomic.AddUint64(&globalFunctionCallCount, 1)
+
 	l := labelsToStrings(f, h)
 
 	// overhead: time from request ingress into router upto proxing into function pod

router/router.go

@@ -94,6 +94,8 @@ func Start(logger *zap.Logger, port int, executorUrl string) {
 	// setup a signal handler for SIGTERM
 	fission.SetupStackTraceHandler()
 
+	_ = MakeAnalytics("")
+
 	fmap := makeFunctionServiceMap(logger, time.Minute)
 
 	frmap := makeFunctionRecorderMap(logger, time.Minute)