add metrics and sample node.js function

.gitignore

@@ -0,0 +1 @@
+fwatchdog

gateway/metrics/metrics.go

@@ -6,8 +6,14 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 )
 
-// Handler returns the global http.Handler that provides the prometheus
-// metrics format on GET requests
-func Handler() http.Handler {
+// MetricOptions to be used by web handlers
+type MetricOptions struct {
+	GatewayRequestsTotal         prometheus.Counter
+	GatewayServerlessServedTotal prometheus.Counter
+	GatewayFunctions             prometheus.Histogram
+}
+
+// PrometheusHandler Bootstraps prometheus for metrics collection
+func PrometheusHandler() http.Handler {
 	return prometheus.Handler()
 }

gateway/server.go

@@ -19,12 +19,6 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 )
 
-type MetricOptions struct {
-	GatewayRequestsTotal         prometheus.Counter
-	GatewayServerlessServedTotal prometheus.Counter
-	GatewayFunctions             prometheus.Histogram
-}
-
 func lookupSwarmService(serviceName string) (bool, error) {
 	var c *client.Client
 	var err error
@@ -39,7 +33,7 @@ func lookupSwarmService(serviceName string) (bool, error) {
 	return len(services) > 0, err
 }
 
-func makeProxy(metrics MetricOptions) http.HandlerFunc {
+func makeProxy(metrics metrics.MetricOptions) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		metrics.GatewayRequestsTotal.Inc()
 
@@ -68,6 +62,9 @@ func makeProxy(metrics MetricOptions) http.HandlerFunc {
 				metrics.GatewayServerlessServedTotal.Inc()
 
 				metrics.GatewayFunctions.Observe(time.Since(start).Seconds())
+			} else {
+				w.WriteHeader(http.StatusBadRequest)
+				w.Write([]byte("Provide an x-function header."))
 			}
 		}
 	}
@@ -92,13 +89,13 @@ func main() {
 	prometheus.Register(GatewayFunctions)
 
 	r := mux.NewRouter()
-	r.HandleFunc("/", makeProxy(MetricOptions{
+	r.HandleFunc("/", makeProxy(metrics.MetricOptions{
 		GatewayRequestsTotal:         GatewayRequestsTotal,
 		GatewayServerlessServedTotal: GatewayServerlessServedTotal,
 		GatewayFunctions:             GatewayFunctions,
 	}))
 
-	metricsHandler := metrics.Handler()
+	metricsHandler := metrics.PrometheusHandler()
 	r.Handle("/metrics", metricsHandler)
 	log.Fatal(http.ListenAndServe(":8080", r))
 }

sample-functions/Dockerfile

@@ -0,0 +1,9 @@
+FROM alpine:latest
+RUN apk --update add nodejs
+COPY ./fwatchdog /usr/bin/
+
+COPY package.json .
+COPY main.js .
+RUN npm i
+ENV fprocess="node main.js"
+CMD ["fwatchdog"]

sample-functions/main.js

@@ -0,0 +1,3 @@
+'use strict'
+let os = require('os');
+console.log(os.platform(), os.arch(), os.cpus(), os.uptime(), os.userInfo());

sample-functions/package.json

@@ -0,0 +1,12 @@
+{
+  "name": "sample-functions",
+  "version": "1.0.0",
+  "description": "",
+  "main": "main.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC"
+}