Add --listen-metrics flag for /metrics endpoint's port

cmd/fluxd/main.go

@@ -74,6 +74,7 @@ func main() {
 	// This mirrors how kubectl extracts information from the environment.
 	var (
 		listenAddr        = fs.StringP("listen", "l", ":3030", "Listen address where /metrics and API will be served")
+		listenMetricsAddr = fs.String("listen-metrics", "", "Listen address for /metrics endpoint")
 		kubernetesKubectl = fs.String("kubernetes-kubectl", "", "Optional, explicit path to kubectl tool")
 		versionFlag       = fs.Bool("version", false, "Get version number")
 		// Git repo & key etc.
@@ -445,12 +446,24 @@ func main() {
 
 	go func() {
 		mux := http.DefaultServeMux
-		mux.Handle("/metrics", promhttp.Handler())
+		// Serve /metrics alongside API
+		if *listenMetricsAddr == "" {
+			mux.Handle("/metrics", promhttp.Handler())
+		}
 		handler := daemonhttp.NewHandler(daemon, daemonhttp.NewRouter())
 		mux.Handle("/api/flux/", http.StripPrefix("/api/flux", handler))
 		logger.Log("addr", *listenAddr)
 		errc <- http.ListenAndServe(*listenAddr, mux)
 	}()
 
+	if *listenMetricsAddr != "" {
+		go func() {
+			mux := http.NewServeMux()
+			mux.Handle("/metrics", promhttp.Handler())
+			logger.Log("metrics-addr", *listenMetricsAddr)
+			errc <- http.ListenAndServe(*listenMetricsAddr, mux)
+		}()
+	}
+
 	// Fall off the end, into the waiting procedure.
 }

deploy/flux-deployment.yaml

@@ -12,6 +12,8 @@ spec:
     type: Recreate
   template:
     metadata:
+      annotations:
+        prometheus.io.port: "3031" # tell prometheus to scrape /metrics endpoint's port.
       labels:
         name: flux
     spec:
@@ -34,7 +36,7 @@ spec:
       # repo rather than using github or the like. You'll also need to
       # mount it into the container, below.
       # - name: ssh-config
-      #   configMap: 
+      #   configMap:
       #     name: flux-ssh-config
 
       containers:
@@ -78,3 +80,7 @@ spec:
         # (e.g., Weave Cloud). The token is particular to the service.
         # - --connect=wss://cloud.weave.works/api/flux
         # - --token=abc123abc123abc123abc123
+
+        # serve /metrics endpoint at different port.
+        # make sure to set prometheus' annotation to scrape the port value.
+        - --listen-metrics=:3031

site/daemon.md

@@ -27,19 +27,20 @@ Version controlling of cluster manifests provides reproducibility and a historic
             Deployment happens automatically when a new image tag is detected.
             Deautomated deployment will not proceed until manually released (through
             the UI or the CLI tool fluxctl).
-            
+
         2.
         Lock vs Unlock
             Deployment is pinned to a particular image tag. New deployment will not
             proceed upon triggered release.
-    
+
 # Flags
 
 fluxd requires setup and offers customization though a multitude of flags.
 
 |flag                    | default                       | purpose |
 |------------------------|-------------------------------|---------|
 |--listen -l             | `:3030`                         | listen address where /metrics and API will be served|
+|--listen-metrics        |                               | listen address for /metrics endpoint |
 |--kubernetes-kubectl    |                               | optional, explicit path to kubectl tool|
 |--version               | false                         | output the version number and exit |
 |**Git repo & key etc.** |                              ||