Serve metrics only with metrics port option

Author: dtaniwaki

bin/configurable-http-proxy

@@ -87,7 +87,8 @@ cli
   )
   .option("--insecure", "Disable SSL cert verification")
   .option("--host-routing", "Use host routing (host as first level of path)")
-  .option("--disable-metrics", "Disable metrics endpoint")
+  .option("--metrics-ip <ip>", "IP for metrics server", "0.0.0.0")
+  .option("--metrics-port <n>", "Port of metrics server. Defaults to no metrics server")
   .option("--log-level <loglevel>", "Log level (debug, info, warn, error)", "info")
   .option(
     "--timeout <n>",
@@ -264,8 +265,8 @@ options.headers = args.customHeader;
 options.timeout = args.timeout;
 options.proxyTimeout = args.proxyTimeout;
 
-// prometheus options
-options.disableMetrics = args.disableMetrics;
+// metrics options
+options.enableMetrics = !!args.metricsPort;
 
 // certs need to be provided for https redirection
 if (!options.ssl && options.redirectPort) {
@@ -318,9 +319,14 @@ if (args.ip === "*") {
 listen.ip = args.ip;
 listen.apiIp = args.apiIp || "localhost";
 listen.apiPort = args.apiPort || listen.port + 1;
+listen.metricsIp = args.metricsIp || "0.0.0.0";
+listen.metricsPort = args.metricsPort;
 
 proxy.proxyServer.listen(listen.port, listen.ip);
 proxy.apiServer.listen(listen.apiPort, listen.apiIp);
+if (listen.metricsPort) {
+  proxy.metricsServer.listen(listen.metricsPort, listen.metricsIp);
+}
 
 log.info(
   "Proxying %s://%s:%s to %s",
@@ -335,6 +341,14 @@ log.info(
   listen.apiIp || "*",
   listen.apiPort
 );
+if (listen.metricsPort) {
+  log.info(
+    "Serve metrics at %s://%s:%s/metrics",
+    "http",
+    listen.metricsIp,
+    listen.metricsPort
+  );
+}
 
 if (args.pidFile) {
   log.info("Writing pid %s to %s", process.pid, args.pidFile);

lib/configproxy.js

@@ -161,10 +161,10 @@ class ConfigurableProxy extends EventEmitter {
     }
     this.errorPath = options.errorPath || path.join(__dirname, "error");
 
-    if (options.disableMetrics) {
-      this.metrics = new metrics.MockMetrics();
-    } else {
+    if (this.options.enableMetrics) {
       this.metrics = new metrics.Metrics();
+    } else {
+      this.metrics = new metrics.MockMetrics();
     }
 
     if (this.options.defaultTarget) {
@@ -213,6 +213,12 @@ class ConfigurableProxy extends EventEmitter {
       this.apiServer = http.createServer(apiCallback);
     }
 
+    // handle metrics
+    if (this.options.enableMetrics) {
+      var metricsCallback = logErrors(that.handleMetrics);
+      this.metricsServer = http.createServer(metricsCallback);
+    }
+
     // proxy requests separately
     var proxyCallback = logErrors(this.handleProxyWeb);
     if (this.options.ssl) {
@@ -617,16 +623,11 @@ class ConfigurableProxy extends EventEmitter {
     if (req.url === "/metrics") {
       return this.metrics.render(res);
     }
+    fail(req, res, 404);
   }
 
   handleApiRequest(req, res) {
     // Handle a request to the REST API
-    if (!this.options.disableMetrics) {
-      var p = this.handleMetrics(req, res);
-      if (p) {
-        return p;
-      }
-    }
     if (res) {
       var that = this;
       res.on("finish", () => {