Add new HTTPServer to serve /metrics on port 8082

This commit runs a new HTTPServer on port 8082 in a goroutine to serve
/metrics endpoint on a different port.

This also update the configurations and compose files.

Fixes: #1081

Signed-off-by: Vivek Singh <vivekkmr45@yahoo.in>

docker-compose.arm64.yml

@@ -3,6 +3,7 @@ services:
     gateway:
         ports:
             - 8080:8080
+            - 8082:8082
         image: openfaas/gateway:0.11.0-arm64
         networks:
             - functions

docker-compose.armhf.yml

@@ -3,6 +3,7 @@ services:
     gateway:
         ports:
             - 8080:8080
+            - 8082:8082
         image: openfaas/gateway:0.11.0-armhf
         networks:
             - functions

docker-compose.yml

@@ -3,6 +3,7 @@ services:
     gateway:
         ports:
             - 8080:8080
+            - 8082:8082
         image: openfaas/gateway:0.11.1
         networks:
             - functions

gateway/Dockerfile

@@ -48,6 +48,7 @@ RUN addgroup -S app \
 WORKDIR /home/app
 
 EXPOSE 8080
+EXPOSE 8082
 ENV http_proxy      ""
 ENV https_proxy     ""
 

gateway/Dockerfile.arm64

@@ -29,6 +29,7 @@ RUN addgroup -S app \
 WORKDIR /home/app
 
 EXPOSE 8080
+EXPOSE 8082
 ENV http_proxy      ""
 ENV https_proxy     ""
 

gateway/Dockerfile.armhf

@@ -48,6 +48,7 @@ RUN addgroup -S app \
 WORKDIR /home/app
 
 EXPOSE 8080
+EXPOSE 8082
 ENV http_proxy      ""
 ENV https_proxy     ""
 

gateway/server.go

@@ -207,7 +207,22 @@ func main() {
 	}
 
 	metricsHandler := metrics.PrometheusHandler()
-	r.Handle("/metrics", metricsHandler)
+
+	//Create a new server to serve /metrics endpoint
+	go func() {
+		routes := mux.NewRouter()
+		routes.Handle("/metrics", metricsHandler)
+		port := 8082
+		s := &http.Server{
+			Addr:           fmt.Sprintf(":%d", port),
+			ReadTimeout:    config.ReadTimeout,
+			WriteTimeout:   config.WriteTimeout,
+			MaxHeaderBytes: http.DefaultMaxHeaderBytes,
+			Handler:        routes,
+		}
+		log.Fatal(s.ListenAndServe())
+	}()
+
 	r.HandleFunc("/healthz", handlers.MakeForwardingProxyHandler(reverseProxy, forwardingNotifiers, urlResolver, nilURLTransformer)).Methods(http.MethodGet)
 
 	r.Handle("/", http.RedirectHandler("/ui/", http.StatusMovedPermanently)).Methods(http.MethodGet)

prometheus/k8s.prometheus.yml

@@ -32,6 +32,6 @@ scrape_configs:
     scrape_interval: 5s
     dns_sd_configs:
       - names: ['gateway.default.svc.cluster.local']
-        port: 8080
+        port: 8082
         type: A
         refresh_interval: 5s

prometheus/prometheus.yml

@@ -32,7 +32,7 @@ scrape_configs:
     scrape_interval: 5s
     dns_sd_configs:
       - names: ['tasks.gateway']
-        port: 8080
+        port: 8082
         type: A
         refresh_interval: 5s