Merge pull request #31 from Comcast/feature/prometheusEndpoint

Feature/prometheus endpoint (WIP)

src/glide.yaml

@@ -7,3 +7,7 @@ import:
   version: v3.3
 - package: gopkg.in/h2non/gock.v1
   version: v1.0.6
+- package: github.com/prometheus/client_golang
+  version: v0.9.0-pre1
+  subpackages:
+  - prometheus

src/tr1d1um/http.go

@@ -46,6 +46,8 @@ type ConversionHandler struct {
 
 //ConversionHandler handles the different incoming tr1 requests
 func (ch *ConversionHandler) ServeHTTP(origin http.ResponseWriter, req *http.Request) {
+	requestsReceived.Inc()
+
 	var (
 		debugLogger = logging.Debug(ch)
 		errorLogger = logging.Error(ch)
@@ -138,6 +140,8 @@ func (ch *ConversionHandler) ServeHTTP(origin http.ResponseWriter, req *http.Req
 
 //HandleStat handles the differentiated STAT command
 func (ch *ConversionHandler) HandleStat(origin http.ResponseWriter, req *http.Request) {
+	requestsReceived.Inc()
+
 	logging.Debug(ch).Log(logging.MessageKey(), "HandleStat called")
 	var errorLogger = logging.Error(ch)
 

src/tr1d1um/tr1d1um.go

@@ -38,6 +38,8 @@ import (
 	"github.com/go-kit/kit/log"
 	"github.com/gorilla/mux"
 	"github.com/justinas/alice"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/spf13/pflag"
 	"github.com/spf13/viper"
 )
@@ -53,6 +55,7 @@ const (
 	defaultNetDialerTimeout = "5s"
 	defaultRetryInterval    = "2s"
 	defaultMaxRetries       = 2
+	defaultMetricsAddress   = ":8080"
 
 	supportedServicesKey = "supportedServices"
 	targetURLKey         = "targetURL"
@@ -61,13 +64,18 @@ const (
 	reqRetryIntervalKey  = "requestRetryInterval"
 	reqMaxRetriesKey     = "requestMaxRetries"
 	respWaitTimeoutKey   = "respWaitTimeout"
+	metricsAddressKey    = "metricsAddress"
 
 	releaseKey = "release"
 )
 
 var (
-	release  = "-"
-	hostname = "-"
+	release          = "-"
+	hostname         = "-"
+	requestsReceived = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "requests_received",
+		Help: "Number of requests (that hit correct endpoints) received by tr1d1um.",
+	})
 )
 
 func tr1d1um(arguments []string) (exitCode int) {
@@ -83,6 +91,7 @@ func tr1d1um(arguments []string) (exitCode int) {
 	v.SetDefault(reqRetryIntervalKey, defaultRetryInterval)
 	v.SetDefault(reqMaxRetriesKey, defaultMaxRetries)
 	v.SetDefault(netDialerTimeoutKey, defaultNetDialerTimeout)
+	v.SetDefault(metricsAddressKey, defaultMetricsAddress)
 
 	//release and internal OS info set up
 	if releaseVal := v.GetString(releaseKey); releaseVal != "" {
@@ -99,7 +108,8 @@ func tr1d1um(arguments []string) (exitCode int) {
 	}
 
 	var (
-		infoLogger = logging.Info(logger)
+		infoLogger  = logging.Info(logger)
+		errorLogger = logging.Error(logger)
 	)
 
 	infoLogger.Log("configurationFile", v.ConfigFileUsed())
@@ -136,6 +146,14 @@ func tr1d1um(arguments []string) (exitCode int) {
 
 	go snsFactory.PrepareAndStart()
 
+	// prometheus metrics set up
+	http.Handle("/metrics", preHandler.Then(promhttp.Handler()))
+	go func() {
+		if prometheusEndpointErr := http.ListenAndServe(v.GetString(metricsAddressKey), nil); prometheusEndpointErr != nil {
+			errorLogger.Log(logging.MessageKey(), "error with prometheus endpoint", logging.ErrorKey(), prometheusEndpointErr)
+		}
+	}()
+
 	if err := concurrent.Await(tr1d1umServer, signals); err != nil {
 		fmt.Fprintf(os.Stderr, "Error when starting %s: %s", applicationName, err)
 		return 4
@@ -315,3 +333,8 @@ func getSupportedServicesMap(supportedServices []string) (supportedServicesMap m
 func main() {
 	os.Exit(tr1d1um(os.Args))
 }
+
+func init() {
+	// Metrics values must be registered to be exposed:
+	prometheus.MustRegister(requestsReceived)
+}