feat(backend-common): introduce metrics for the backend

Add a /metrics endpoint that exposes metrics about the backend. It provides general runtime metrics (memory, gc, utilization) as well as request metrics.
2020-08-27 14:40:22 +02:00
parent 70ccbd304c
commit 8f6038951f
4 changed files with 74 additions and 1 deletions
@@ -37,11 +37,13 @@
    "compression": "^1.7.4",
    "cors": "^2.8.5",
    "express": "^4.17.1",
+    "express-prom-bundle": "^6.1.0",
    "express-promise-router": "^3.0.3",
    "helmet": "^4.0.0",
    "knex": "^0.21.1",
    "lodash": "^4.17.15",
    "morgan": "^1.10.0",
+    "prom-client": "^12.0.0",
    "selfsigned": "^1.10.7",
    "stoppable": "^1.1.0",
    "winston": "^3.2.1"
@@ -37,6 +37,7 @@ import {
  HttpsSettings,
 } from './config';
 import { createHttpServer, createHttpsServer } from './hostFactory';
+import { metricsHandler } from './metrics';

 const DEFAULT_PORT = 7000;
 // '' is express default, which listens to all interfaces
@@ -131,6 +132,7 @@ export class ServiceBuilderImpl implements ServiceBuilder {
    }
    app.use(compression());
    app.use(express.json());
+    app.use(metricsHandler());
    app.use(requestLoggingHandler());
    for (const [root, route] of this.routers) {
      app.use(root, route);
@@ -0,0 +1,37 @@
+/*
+ * Copyright 2020 Spotify AB
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+import prom from 'prom-client';
+import promBundle from 'express-prom-bundle';
+import { RequestHandler } from 'express';
+
+/**
+ * Adds a /metrics endpoint, register default runtime metrics and instrument the router.
+ */
+export function metricsHandler(): RequestHandler {
+  // We can only initialize the metrics once and have to clean them up between hot reloads
+  prom.register.clear();
+
+  return promBundle({
+    includeMethod: true,
+    includePath: true,
+    // Using includePath alone is problematic, as it will include path labels with high
+    // cardinality (e.g. path params). Instead we would have to template them. However, this
+    // is difficult, as every backend plugin might use different routes. Instead we only take
+    // the first directory of the path, to have at least an idea how each plugin performs:
+    normalizePath: [['^/([^/]*)/.*', '/$1']],
+    promClient: { collectDefaultMetrics: {} },
+  });
+}
@@ -6511,6 +6511,11 @@ bindings@^1.5.0:
  dependencies:
    file-uri-to-path "1.0.0"

+bintrees@1.0.1:
+  version "1.0.1"
+  resolved "https://registry.npmjs.org/bintrees/-/bintrees-1.0.1.tgz#0e655c9b9c2435eaab68bf4027226d2b55a34524"
+  integrity sha1-DmVcm5wkNeqraL9AJyJtK1WjRSQ=
+
 bl@^1.0.0:
  version "1.2.2"
  resolved "https://registry.npmjs.org/bl/-/bl-1.2.2.tgz#a160911717103c07410cef63ef51b397c025af9c"
@@ -10135,6 +10140,14 @@ expect@^26.0.1:
    jest-message-util "^26.0.1"
    jest-regex-util "^26.0.0"

+express-prom-bundle@^6.1.0:
+  version "6.1.0"
+  resolved "https://registry.npmjs.org/express-prom-bundle/-/express-prom-bundle-6.1.0.tgz#8fd72e5bedbbd686b8e7c49e0aecbc1b14b28743"
+  integrity sha512-krlvp5r6sgJ1IwL6M6/coMrNbAlwtpk+uyivfeyRMCupTK4HzIEQHH0gwrNhLiKyPmSbtZcSmtO6s+PRumRp5g==
+  dependencies:
+    on-finished "^2.3.0"
+    url-value-parser "^2.0.0"
+
 express-promise-router@^3.0.3:
  version "3.0.3"
  resolved "https://registry.npmjs.org/express-promise-router/-/express-promise-router-3.0.3.tgz#5e6d22a5a3f013d71833172fe8d7ab780c3f6b70"
@@ -16227,7 +16240,7 @@ omggif@1.0.7:
  resolved "https://registry.npmjs.org/omggif/-/omggif-1.0.7.tgz#59d2eecb0263de84635b3feb887c0c9973f1e49d"
  integrity sha1-WdLuywJj3oRjWz/riHwMmXPx5J0=

-on-finished@~2.3.0:
+on-finished@^2.3.0, on-finished@~2.3.0:
  version "2.3.0"
  resolved "https://registry.npmjs.org/on-finished/-/on-finished-2.3.0.tgz#20f1336481b083cd75337992a16971aa2d906947"
  integrity sha1-IPEzZIGwg811M3mSoWlxqi2QaUc=
@@ -17809,6 +17822,13 @@ progress@^2.0.0:
  resolved "https://registry.npmjs.org/progress/-/progress-2.0.3.tgz#7e8cf8d8f5b8f239c1bc68beb4eb78567d572ef8"
  integrity sha512-7PiHtLll5LdnKIMw100I+8xJXR5gW2QwWYkT6iJva0bXitZKa/XMrSbdmg3r2Xnaidz9Qumd0VPaMrZlF9V9sA==

+prom-client@^12.0.0:
+  version "12.0.0"
+  resolved "https://registry.npmjs.org/prom-client/-/prom-client-12.0.0.tgz#9689379b19bd3f6ab88a9866124db9da3d76c6ed"
+  integrity sha512-JbzzHnw0VDwCvoqf8y1WDtq4wSBAbthMB1pcVI/0lzdqHGJI3KBJDXle70XK+c7Iv93Gihqo0a5LlOn+g8+DrQ==
+  dependencies:
+    tdigest "^0.1.1"
+
 promise-inflight@^1.0.1:
  version "1.0.1"
  resolved "https://registry.npmjs.org/promise-inflight/-/promise-inflight-1.0.1.tgz#98472870bf228132fcbdd868129bad12c3c029e3"
@@ -21142,6 +21162,13 @@ tcp-port-used@^1.0.1:
    debug "4.1.0"
    is2 "2.0.1"

+tdigest@^0.1.1:
+  version "0.1.1"
+  resolved "https://registry.npmjs.org/tdigest/-/tdigest-0.1.1.tgz#2e3cb2c39ea449e55d1e6cd91117accca4588021"
+  integrity sha1-Ljyyw56kSeVdHmzZEReszKRYgCE=
+  dependencies:
+    bintrees "1.0.1"
+
 telejson@^3.2.0:
  version "3.3.0"
  resolved "https://registry.npmjs.org/telejson/-/telejson-3.3.0.tgz#6d814f3c0d254d5c4770085aad063e266b56ad03"
@@ -22131,6 +22158,11 @@ url-to-options@^1.0.1:
  resolved "https://registry.npmjs.org/url-to-options/-/url-to-options-1.0.1.tgz#1505a03a289a48cbd7a434efbaeec5055f5633a9"
  integrity sha1-FQWgOiiaSMvXpDTvuu7FBV9WM6k=

+url-value-parser@^2.0.0:
+  version "2.0.1"
+  resolved "https://registry.npmjs.org/url-value-parser/-/url-value-parser-2.0.1.tgz#c8179a095ab9ec1f5aa17ca36af5af396b4e95ed"
+  integrity sha512-bexECeREBIueboLGM3Y1WaAzQkIn+Tca/Xjmjmfd0S/hFHSCEoFkNh0/D0l9G4K74MkEP/lLFRlYnxX3d68Qgw==
+
 url@^0.11.0, url@~0.11.0:
  version "0.11.0"
  resolved "https://registry.npmjs.org/url/-/url-0.11.0.tgz#3838e97cfc60521eb73c525a8e55bfdd9e2e28f1"