feat: added prometheus metrics support

Dockerfile

@@ -6,6 +6,7 @@ RUN apk update && \
     apk upgrade && \
     apk add openssl && \
     apk add nginx && \
+    apk add nginx-mod-http-vts && \
     rm -rf /var/cache/apk/*
 
 ADD . /app

config/default.ts

@@ -16,8 +16,9 @@
 import {ConfigFile} from '../src/common';
 
 const config: ConfigFile = {
-  activeVersions: ['1\\.0\\.\\d+','2\\.0\\.\\d+'],
+  activeVersions: ['1\\.0\\.\\d+', '2\\.0\\.\\d+'],
   hiddenRoutes: ['/bulk'],
+  metrics: false,
   outdatedVersions: ['0\\.8\\.\\d+', '0\\.5\\.\\d+', '0\\.6\\.\\d+', '0\\.7\\.\\d+'],
   output: '/etc/nginx/http.d/default.conf',
   rateLimitAllowList: ['127.0.0.1/32'],

fixtures/metrics.template

@@ -0,0 +1,7 @@
+server {
+    listen 8080;
+    location /metrics {
+      vhost_traffic_status_display;
+      vhost_traffic_status_display_format prometheus;
+    }
+}

nginx.conf

@@ -1,3 +1,5 @@
+load_module modules/ngx_http_vhost_traffic_status_module.so;
+
 worker_processes  1;
 
 error_log stderr;
@@ -9,6 +11,7 @@ events {
 }
 
 http {
+  vhost_traffic_status_zone;
   include       mime.types;
   default_type  application/octet-stream;
   access_log    /dev/stdout;

nginx.conf.template

@@ -1,3 +1,5 @@
+{{{ metrics }}}
+
 {{{ dockerVersionMap }}}
 
 # create a custom request limit zone which can handle 160,000 IP-Addresses at the same time

src/common.ts

@@ -59,12 +59,16 @@ export interface ConfigFile {
    * List of hidden routes
    */
   hiddenRoutes: string[];
+  /**
+   * Enables metrics on /metrics route
+   */
+  metrics: boolean;
   /**
    * List of outdated versions
    */
   outdatedVersions: string[];
   /**
-   * Output?! TODO
+   * Path the generated config will be written to
    */
   output: string;
   /**
@@ -93,6 +97,10 @@ export interface TemplateView {
    * Listener
    */
   listener: string;
+  /**
+   * Local server with listener for /metrics route
+   */
+  metrics: string;
   /**
    * Allow list for rate limiting
    */

src/main.ts

@@ -241,6 +241,16 @@ ${protocolHardeningParameters}
   return listener;
 }
 
+/**
+ * Reads predefined server entry with metrics location
+ */
+export async function generateMetricsServer(enableMetrics: boolean): Promise<string> {
+  if (!enableMetrics) {
+    return '';
+  }
+  return asyncReadFile('./fixtures/metrics.template', 'utf8');
+}
+
 /**
  * Render a mustache template file with given view object
  *
@@ -300,6 +310,7 @@ export async function getTemplateView(containers: Dockerode.ContainerInfo[]): Pr
     ),
     hiddenRoutes: (await Promise.all(hiddenRoutesPromises)).join(''),
     listener: generateListener(configFile.sslFilePaths),
+    metrics: await generateMetricsServer(configFile.metrics),
     rateLimitAllowList: generateRateLimitAllowList(configFile.rateLimitAllowList),
     staticRoute: await renderTemplate(path.join('fixtures', 'staticRoute.template'), {cors}),
     visibleRoutes: (await Promise.all(visibleRoutesPromises)).join(''),

test/main.spec.ts

@@ -31,6 +31,7 @@ import {
   getGatewayOfStAppsBackend,
   getTemplateView,
   generateListener,
+  generateMetricsServer,
   getContainers,
 } from '../src/main';
 import {resolve} from 'path';
@@ -399,6 +400,16 @@ Please check if docker is running and Node.js can access the docker socket (/var
     return true;
   }
 
+  @test
+  async 'include metrics config'() {
+    expect(await generateMetricsServer(true)).length.to.be.greaterThan(1);
+  }
+
+  @test
+  async 'omit metrics config'() {
+    expect(await generateMetricsServer(false)).to.equal('');
+  }
+
   @test
   'create listener faulty config'() {
     expect(