add prometheus request metrics

server/handlerequest.go

@@ -4,19 +4,26 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"time"
 
 	"github.com/foomo/contentserver/log"
 	"github.com/foomo/contentserver/repo"
 	"github.com/foomo/contentserver/requests"
 	"github.com/foomo/contentserver/responses"
+	"github.com/foomo/contentserver/status"
+	"github.com/prometheus/client_golang/prometheus"
 )
 
-func handleRequest(r *repo.Repo, handler Handler, jsonBytes []byte) (replyBytes []byte, err error) {
+func handleRequest(r *repo.Repo, handler Handler, jsonBytes []byte, metrics *status.Metrics) (replyBytes []byte, err error) {
 
+	// variables
 	var reply interface{}
 	var apiErr error
 	var jsonErr error
 
+	start := time.Now()
+
+	// helper processor
 	processIfJSONIsOk := func(err error, processingFunc func()) {
 		if err != nil {
 			jsonErr = err
@@ -25,37 +32,46 @@ func handleRequest(r *repo.Repo, handler Handler, jsonBytes []byte) (replyBytes
 		processingFunc()
 	}
 
+	// handle and process
 	switch handler {
 	case HandlerGetURIs:
 		getURIRequest := &requests.URIs{}
 		processIfJSONIsOk(json.Unmarshal(jsonBytes, &getURIRequest), func() {
 			reply = r.GetURIs(getURIRequest.Dimension, getURIRequest.IDs)
 		})
+		addMetrics(metrics, HandlerGetURIs, start, jsonErr, apiErr)
 	case HandlerGetContent:
 		contentRequest := &requests.Content{}
 		processIfJSONIsOk(json.Unmarshal(jsonBytes, &contentRequest), func() {
 			reply, apiErr = r.GetContent(contentRequest)
 		})
+		addMetrics(metrics, HandlerGetContent, start, jsonErr, apiErr)
 	case HandlerGetNodes:
 		nodesRequest := &requests.Nodes{}
 		processIfJSONIsOk(json.Unmarshal(jsonBytes, &nodesRequest), func() {
 			reply = r.GetNodes(nodesRequest)
 		})
+		addMetrics(metrics, HandlerGetNodes, start, jsonErr, apiErr)
 	case HandlerUpdate:
 		updateRequest := &requests.Update{}
 		processIfJSONIsOk(json.Unmarshal(jsonBytes, &updateRequest), func() {
 			reply = r.Update()
 		})
+		addMetrics(metrics, HandlerUpdate, start, jsonErr, apiErr)
 	case HandlerGetRepo:
 		repoRequest := &requests.Repo{}
 		processIfJSONIsOk(json.Unmarshal(jsonBytes, &repoRequest), func() {
 			reply = r.GetRepo()
 		})
+		addMetrics(metrics, HandlerGetRepo, start, jsonErr, apiErr)
 	default:
 		err = errors.New(log.Error("  can not handle this one " + handler))
 		errorResponse := responses.NewError(1, "unknown handler")
 		reply = errorResponse
+		addMetrics(metrics, "default", start, jsonErr, apiErr)
 	}
+
+	// error handling
 	if jsonErr != nil {
 		err = jsonErr
 		log.Error("  could not read incoming json:", jsonErr)
@@ -66,9 +82,30 @@ func handleRequest(r *repo.Repo, handler Handler, jsonBytes []byte) (replyBytes
 		err = apiErr
 		reply = responses.NewError(3, "internal error "+apiErr.Error())
 	}
+
 	return encodeReply(reply)
 }
 
+func addMetrics(metrics *status.Metrics, handlerName Handler, start time.Time, errJSON error, errAPI error) {
+
+	duration := time.Since(start)
+
+	s := "succeeded"
+	if errJSON != nil || errAPI != nil {
+		s = "failed"
+	}
+
+	metrics.ServiceRequestCounter.With(prometheus.Labels{
+		status.MetricLabelHandler: string(handlerName),
+		status.MetricLabelStatus:  s,
+	}).Inc()
+
+	metrics.ServiceRequestDuration.With(prometheus.Labels{
+		status.MetricLabelHandler: string(handlerName),
+		status.MetricLabelStatus:  s,
+	}).Observe(float64(duration.Nanoseconds()))
+}
+
 func encodeReply(reply interface{}) (replyBytes []byte, err error) {
 	encodedBytes, jsonReplyErr := json.MarshalIndent(map[string]interface{}{
 		"reply": reply,

server/server.go

@@ -74,19 +74,23 @@ func runSocketServer(
 	address string,
 	chanErr chan error,
 ) {
-	s := &socketServer{
-		stats: newStats(),
-		repo:  repo,
-	}
-	ln, err := net.Listen("tcp", address)
-	if err != nil {
-		err = errors.New("RunSocketServer: could not start the on \"" + address + "\" - error: " + fmt.Sprint(err))
-		// failed to create socket
-		log.Error(err)
-		chanErr <- err
+	// create socket server
+	s, errSocketServer := newSocketServer(repo)
+	if errSocketServer != nil {
+		log.Error(errSocketServer)
+		chanErr <- errSocketServer
 		return
 	}
-	// there we go
+
+	// listen on socket
+	ln, errListen := net.Listen("tcp", address)
+	if errListen != nil {
+		errListenSocket := errors.New("RunSocketServer: could not start the on \"" + address + "\" - error: " + fmt.Sprint(errListen))
+		log.Error(errListenSocket)
+		chanErr <- errListenSocket
+		return
+	}
+
 	log.Record("RunSocketServer: started to listen on " + address)
 	for {
 		// this blocks until connection or error

server/socketserver.go

@@ -10,39 +10,21 @@ import (
 	"github.com/foomo/contentserver/log"
 	"github.com/foomo/contentserver/repo"
 	"github.com/foomo/contentserver/responses"
+	"github.com/foomo/contentserver/status"
 )
 
-// simple internal request counter
-type stats struct {
-	requests  int64
-	chanCount chan int
-}
-
-func newStats() *stats {
-	s := &stats{
-		requests:  0,
-		chanCount: make(chan int),
-	}
-	go func() {
-		for {
-			select {
-			case <-s.chanCount:
-				s.requests++
-				s.chanCount <- 1
-			}
-		}
-	}()
-	return s
-}
-
-func (s *stats) countRequest() {
-	s.chanCount <- 1
-	<-s.chanCount
-}
-
 type socketServer struct {
-	stats *stats
-	repo  *repo.Repo
+	repo    *repo.Repo
+	metrics *status.Metrics
+}
+
+// newSocketServer returns a shiny new socket server
+func newSocketServer(repo *repo.Repo) (s *socketServer, err error) {
+	s = &socketServer{
+		repo:    repo,
+		metrics: status.NewMetrics("socketserver"),
+	}
+	return
 }
 
 func extractHandlerAndJSONLentgh(header string) (handler Handler, jsonLength int, err error) {
@@ -58,12 +40,10 @@ func extractHandlerAndJSONLentgh(header string) (handler Handler, jsonLength int
 }
 
 func (s *socketServer) execute(handler Handler, jsonBytes []byte) (reply []byte) {
-	s.stats.countRequest()
-	log.Notice("socketServer.execute: ", s.stats.requests, ", ", handler)
 	if log.SelectedLevel == log.LevelDebug {
 		log.Debug("  incoming json buffer:", string(jsonBytes))
 	}
-	reply, handlingError := handleRequest(s.repo, handler, jsonBytes)
+	reply, handlingError := handleRequest(s.repo, handler, jsonBytes, s.metrics)
 	if handlingError != nil {
 		log.Error("socketServer.execute handlingError :", handlingError)
 	}

server/webserver.go

@@ -5,19 +5,23 @@ import (
 	"net/http"
 	"strings"
 
+	"github.com/foomo/contentserver/status"
+
 	"github.com/foomo/contentserver/repo"
 )
 
 type webServer struct {
-	r    *repo.Repo
-	path string
+	r       *repo.Repo
+	path    string
+	metrics *status.Metrics
 }
 
 // NewWebServer returns a shiny new web server
 func NewWebServer(path string, r *repo.Repo) (s http.Handler, err error) {
 	s = &webServer{
-		r:    r,
-		path: path,
+		r:       r,
+		path:    path,
+		metrics: status.NewMetrics("webserver"),
 	}
 	return
 }
@@ -33,7 +37,7 @@ func (s *webServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "failed to read incoming request", http.StatusBadRequest)
 		return
 	}
-	reply, errReply := handleRequest(s.r, Handler(strings.TrimPrefix(r.URL.Path, s.path+"/")), jsonBytes)
+	reply, errReply := handleRequest(s.r, Handler(strings.TrimPrefix(r.URL.Path, s.path+"/")), jsonBytes, s.metrics)
 	if errReply != nil {
 		http.Error(w, errReply.Error(), http.StatusInternalServerError)
 		return

status/metrics.go

@@ -0,0 +1,43 @@
+package status
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+const MetricLabelHandler = "handler"
+const MetricLabelStatus = "status"
+
+type Metrics struct {
+	ServiceRequestCounter  *prometheus.CounterVec // count the number of requests for each service function
+	ServiceRequestDuration *prometheus.SummaryVec // count the duration of requests for each service function
+}
+
+func NewMetrics(namespace string) *Metrics {
+	return &Metrics{
+		ServiceRequestCounter:  serviceRequestCounter("api", namespace),
+		ServiceRequestDuration: serviceRequestDuration("api", namespace),
+	}
+}
+
+func serviceRequestCounter(subsystem, namespace string) *prometheus.CounterVec {
+	vec := prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Namespace: namespace,
+			Subsystem: subsystem,
+			Name:      "count_service_requests",
+			Help:      "count of requests per func",
+		}, []string{MetricLabelHandler, MetricLabelStatus})
+	prometheus.MustRegister(vec)
+	return vec
+}
+
+func serviceRequestDuration(subsystem, namespace string) *prometheus.SummaryVec {
+	vec := prometheus.NewSummaryVec(prometheus.SummaryOpts{
+		Namespace: namespace,
+		Subsystem: subsystem,
+		Name:      "time_nanoseconds",
+		Help:      "nanoseconds to unmarshal requests, execute a service function and marshal its reponses",
+	}, []string{MetricLabelHandler, MetricLabelStatus})
+	prometheus.MustRegister(vec)
+	return vec
+}