diff --git a/extensions/metrics/.npmrc b/extensions/metrics/.npmrc
new file mode 100644
index 000000000000..cafe685a112d
--- /dev/null
+++ b/extensions/metrics/.npmrc
@@ -0,0 +1 @@
+package-lock=true
diff --git a/extensions/metrics/LICENSE b/extensions/metrics/LICENSE
new file mode 100644
index 000000000000..ae59dda5b146
--- /dev/null
+++ b/extensions/metrics/LICENSE
@@ -0,0 +1,25 @@
+Copyright (c) IBM Corp. 2019. All Rights Reserved.
+Node module: @loopback/extension-metrics
+This project is licensed under the MIT License, full text below.
+
+--------
+
+MIT license
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
diff --git a/extensions/metrics/README.md b/extensions/metrics/README.md
new file mode 100644
index 000000000000..dedb756a5117
--- /dev/null
+++ b/extensions/metrics/README.md
@@ -0,0 +1,192 @@
+# @loopback/extension-metrics
+
+This module contains a component that reports metrics of Node.js, LoopBack
+framework, and your application to [Prometheus](https://prometheus.io/).
+
+## Stability: :warning:Experimental:warning:
+
+> Experimental packages provide early access to advanced or experimental
+> functionality to get community feedback. Such modules are published to npm
+> using `0.x.y` versions. Their APIs and functionality may be subject to
+> breaking changes in future releases.
+
+## Installation
+
+```sh
+npm install --save @loopback/extension-metrics
+```
+
+## Basic use
+
+The component should be loaded in the constructor of your custom Application
+class.
+
+Start by importing the component class:
+
+```ts
+import {MetricsComponent} from '@loopback/extension-metrics';
+```
+
+In the constructor, add the component to your application:
+
+```ts
+this.component(MetricsComponent);
+```
+
+By default, Metrics route is mounted at `/metrics`. This path can be customized
+via Metrics configuration as follows:
+
+```ts
+this.configure(MetricsBindings.COMPONENT).to({
+ endpoint: {
+ basePath: '/metrics',
+ },
+ defaultMetrics: {
+ timeout: 5000,
+ },
+});
+```
+
+## Metrics Collected
+
+There are three types of metrics being collected by this component:
+
+1. Node.js metrics - built-in by https://github.com/siimon/prom-client
+2. LoopBack method invocations - built-in by this module using an interceptor
+3. Metrics by the application code or other modules - instrumentations are
+ required
+
+## Pull vs Push
+
+Prometheus supports two modes to collect metrics:
+
+- pull - scraping from metrics http endpoint exposed by the system being
+ monitored
+- push - pushing metrics from the system being monitored to a push gateway
+
+See
+https://prometheus.io/docs/introduction/faq/#why-do-you-pull-rather-than-push
+
+## Try it out
+
+```sh
+git clone https://github.com/strongloop/loopback-next
+npm install
+npm run build
+cd examples/metrics-prometheus
+npm run demo
+```
+
+Open http://localhost:9090 to load Prometheus web UI.
+
+### /metrics endpoint
+
+http://localhost:3000/metrics returns metrics in plain text format. It includes
+information for the Node.js process as well as LoopBack method invocations.
+
+
+Example of plain text data
+
+# HELP process_cpu_user_seconds_total Total user CPU time spent in seconds.
+# TYPE process_cpu_user_seconds_total counter
+process_cpu_user_seconds_total 0.132181 1564508354524
+# HELP process_cpu_system_seconds_total Total system CPU time spent in seconds.
+# TYPE process_cpu_system_seconds_total counter
+process_cpu_system_seconds_total 0.023608999999999998 1564508354524
+# HELP process_cpu_seconds_total Total user and system CPU time spent in seconds.
+# TYPE process_cpu_seconds_total counter
+process_cpu_seconds_total 0.15578999999999998 1564508354524
+# HELP process_start_time_seconds Start time of the process since unix epoch in seconds.
+# TYPE process_start_time_seconds gauge
+process_start_time_seconds 1564508343
+# HELP process_resident_memory_bytes Resident memory size in bytes.
+# TYPE process_resident_memory_bytes gauge
+process_resident_memory_bytes 61800448 1564508354524
+# HELP nodejs_eventloop_lag_seconds Lag of event loop in seconds.
+# TYPE nodejs_eventloop_lag_seconds gauge
+nodejs_eventloop_lag_seconds 0.002172946 1564508354526
+# HELP nodejs_active_handles Number of active libuv handles grouped by handle type. Every handle type is C++ class name.
+# TYPE nodejs_active_handles gauge
+nodejs_active_handles{type="WriteStream"} 2 1564508354524
+nodejs_active_handles{type="Server"} 1 1564508354524
+nodejs_active_handles{type="Socket"} 2 1564508354524
+# HELP nodejs_active_handles_total Total number of active handles.
+# TYPE nodejs_active_handles_total gauge
+nodejs_active_handles_total 5 1564508354526
+# HELP nodejs_active_requests Number of active libuv requests grouped by request type. Every request type is C++ class name.
+# TYPE nodejs_active_requests gauge
+# HELP nodejs_active_requests_total Total number of active requests.
+# TYPE nodejs_active_requests_total gauge
+nodejs_active_requests_total 0 1564508354526
+# HELP nodejs_heap_size_total_bytes Process heap size from node.js in bytes.
+# TYPE nodejs_heap_size_total_bytes gauge
+nodejs_heap_size_total_bytes 27545600 1564508354526
+# HELP nodejs_heap_size_used_bytes Process heap size used from node.js in bytes.
+# TYPE nodejs_heap_size_used_bytes gauge
+nodejs_heap_size_used_bytes 23788272 1564508354526
+# HELP nodejs_external_memory_bytes Nodejs external memory size in bytes.
+# TYPE nodejs_external_memory_bytes gauge
+nodejs_external_memory_bytes 1234918 1564508354526
+# HELP nodejs_heap_space_size_total_bytes Process heap space size total from node.js in bytes.
+# TYPE nodejs_heap_space_size_total_bytes gauge
+nodejs_heap_space_size_total_bytes{space="read_only"} 524288 1564508354526
+nodejs_heap_space_size_total_bytes{space="new"} 1048576 1564508354526
+nodejs_heap_space_size_total_bytes{space="old"} 16900096 1564508354526
+nodejs_heap_space_size_total_bytes{space="code"} 688128 1564508354526
+nodejs_heap_space_size_total_bytes{space="map"} 1576960 1564508354526
+nodejs_heap_space_size_total_bytes{space="large_object"} 6758400 1564508354526
+nodejs_heap_space_size_total_bytes{space="code_large_object"} 49152 1564508354526
+nodejs_heap_space_size_total_bytes{space="new_large_object"} 0 1564508354526
+# HELP nodejs_heap_space_size_used_bytes Process heap space size used from node.js in bytes.
+# TYPE nodejs_heap_space_size_used_bytes gauge
+nodejs_heap_space_size_used_bytes{space="read_only"} 31712 1564508354526
+nodejs_heap_space_size_used_bytes{space="new"} 9584 1564508354526
+nodejs_heap_space_size_used_bytes{space="old"} 15723128 1564508354526
+nodejs_heap_space_size_used_bytes{space="code"} 377600 1564508354526
+nodejs_heap_space_size_used_bytes{space="map"} 918480 1564508354526
+nodejs_heap_space_size_used_bytes{space="large_object"} 6726408 1564508354526
+nodejs_heap_space_size_used_bytes{space="code_large_object"} 3456 1564508354526
+nodejs_heap_space_size_used_bytes{space="new_large_object"} 0 1564508354526
+# HELP nodejs_heap_space_size_available_bytes Process heap space size available from node.js in bytes.
+# TYPE nodejs_heap_space_size_available_bytes gauge
+nodejs_heap_space_size_available_bytes{space="read_only"} 492264 1564508354526
+nodejs_heap_space_size_available_bytes{space="new"} 1038368 1564508354526
+nodejs_heap_space_size_available_bytes{space="old"} 1105240 1564508354526
+nodejs_heap_space_size_available_bytes{space="code"} 285952 1564508354526
+nodejs_heap_space_size_available_bytes{space="map"} 657072 1564508354526
+nodejs_heap_space_size_available_bytes{space="large_object"} 0 1564508354526
+nodejs_heap_space_size_available_bytes{space="code_large_object"} 0 1564508354526
+nodejs_heap_space_size_available_bytes{space="new_large_object"} 1047952 1564508354526
+# HELP nodejs_version_info Node.js version info.
+# TYPE nodejs_version_info gauge
+nodejs_version_info{version="v12.4.0",major="12",minor="4",patch="0"} 1
+# HELP loopback_invocation_duration_seconds method invocation
+# TYPE loopback_invocation_duration_seconds gauge
+# HELP loopback_invocation_duration_histogram method invocation histogram
+# TYPE loopback_invocation_duration_histogram histogram
+# HELP loopback_invocation_total method invocation counts
+# TYPE loopback_invocation_total counter
+loopback_invocation_total 1
+# HELP loopback_invocation_duration_summary method invocation summary
+# TYPE loopback_invocation_duration_summary summary
+
+
+
+
+## Contributions
+
+- [Guidelines](https://github.com/strongloop/loopback-next/blob/master/docs/CONTRIBUTING.md)
+- [Join the team](https://github.com/strongloop/loopback-next/issues/110)
+
+## Tests
+
+Run `npm test` from the root folder.
+
+## Contributors
+
+See
+[all contributors](https://github.com/strongloop/loopback-next/graphs/contributors).
+
+## License
+
+MIT
diff --git a/extensions/metrics/bin/start-pushgateway.sh b/extensions/metrics/bin/start-pushgateway.sh
new file mode 100755
index 000000000000..cc530eaf1c51
--- /dev/null
+++ b/extensions/metrics/bin/start-pushgateway.sh
@@ -0,0 +1,7 @@
+#!/bin/bash
+BASE_DIR=`dirname "$0"`
+$BASE_DIR/stop-pushgateway.sh
+
+PROM_PGW_CONTAINER_NAME="prom_pushgateway_lb4"
+docker pull prom/pushgateway:latest
+docker run --name $PROM_PGW_CONTAINER_NAME -p 9091:9091 -d prom/pushgateway:latest
diff --git a/extensions/metrics/bin/stop-pushgateway.sh b/extensions/metrics/bin/stop-pushgateway.sh
new file mode 100755
index 000000000000..0fb78bf21577
--- /dev/null
+++ b/extensions/metrics/bin/stop-pushgateway.sh
@@ -0,0 +1,3 @@
+#!/bin/bash
+PROM_PGW_CONTAINER_NAME="prom_pushgateway_lb4"
+docker rm -f $PROM_PGW_CONTAINER_NAME
diff --git a/extensions/metrics/index.d.ts b/extensions/metrics/index.d.ts
new file mode 100644
index 000000000000..4771c0d1bed3
--- /dev/null
+++ b/extensions/metrics/index.d.ts
@@ -0,0 +1,6 @@
+// Copyright IBM Corp. 2018. All Rights Reserved.
+// Node module: @loopback/extension-metrics
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+export * from './dist';
diff --git a/extensions/metrics/index.js b/extensions/metrics/index.js
new file mode 100644
index 000000000000..368652de64a5
--- /dev/null
+++ b/extensions/metrics/index.js
@@ -0,0 +1,6 @@
+// Copyright IBM Corp. 2019. All Rights Reserved.
+// Node module: @loopback/extension-metrics
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+module.exports = require('./dist');
diff --git a/extensions/metrics/index.ts b/extensions/metrics/index.ts
new file mode 100644
index 000000000000..c2d70ccb419b
--- /dev/null
+++ b/extensions/metrics/index.ts
@@ -0,0 +1,8 @@
+// Copyright IBM Corp. 2019. All Rights Reserved.
+// Node module: @loopback/extension-metrics
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+// DO NOT EDIT THIS FILE
+// Add any additional (re)exports to src/index.ts instead.
+export * from './src';
diff --git a/extensions/metrics/package-lock.json b/extensions/metrics/package-lock.json
new file mode 100644
index 000000000000..3beec1491741
--- /dev/null
+++ b/extensions/metrics/package-lock.json
@@ -0,0 +1,536 @@
+{
+ "name": "@loopback/extension-metrics",
+ "version": "0.0.1",
+ "lockfileVersion": 1,
+ "requires": true,
+ "dependencies": {
+ "@types/body-parser": {
+ "version": "1.17.1",
+ "resolved": "https://registry.npmjs.org/@types/body-parser/-/body-parser-1.17.1.tgz",
+ "integrity": "sha512-RoX2EZjMiFMjZh9lmYrwgoP9RTpAjSHiJxdp4oidAQVO02T7HER3xj9UKue5534ULWeqVEkujhWcyvUce+d68w==",
+ "dev": true,
+ "requires": {
+ "@types/connect": "*",
+ "@types/node": "*"
+ }
+ },
+ "@types/connect": {
+ "version": "3.4.32",
+ "resolved": "https://registry.npmjs.org/@types/connect/-/connect-3.4.32.tgz",
+ "integrity": "sha512-4r8qa0quOvh7lGD0pre62CAb1oni1OO6ecJLGCezTmhQ8Fz50Arx9RUszryR8KlgK6avuSXvviL6yWyViQABOg==",
+ "dev": true,
+ "requires": {
+ "@types/node": "*"
+ }
+ },
+ "@types/express": {
+ "version": "4.17.1",
+ "resolved": "https://registry.npmjs.org/@types/express/-/express-4.17.1.tgz",
+ "integrity": "sha512-VfH/XCP0QbQk5B5puLqTLEeFgR8lfCJHZJKkInZ9mkYd+u8byX0kztXEQxEk4wZXJs8HI+7km2ALXjn4YKcX9w==",
+ "dev": true,
+ "requires": {
+ "@types/body-parser": "*",
+ "@types/express-serve-static-core": "*",
+ "@types/serve-static": "*"
+ }
+ },
+ "@types/express-serve-static-core": {
+ "version": "4.16.10",
+ "resolved": "https://registry.npmjs.org/@types/express-serve-static-core/-/express-serve-static-core-4.16.10.tgz",
+ "integrity": "sha512-gM6evDj0OvTILTRKilh9T5dTaGpv1oYiFcJAfgSejuMJgGJUsD9hKEU2lB4aiTNy4WwChxRnjfYFuBQsULzsJw==",
+ "requires": {
+ "@types/node": "*",
+ "@types/range-parser": "*"
+ }
+ },
+ "@types/mime": {
+ "version": "2.0.1",
+ "resolved": "https://registry.npmjs.org/@types/mime/-/mime-2.0.1.tgz",
+ "integrity": "sha512-FwI9gX75FgVBJ7ywgnq/P7tw+/o1GUbtP0KzbtusLigAOgIgNISRK0ZPl4qertvXSIE8YbsVJueQ90cDt9YYyw==",
+ "dev": true
+ },
+ "@types/node": {
+ "version": "10.14.19",
+ "resolved": "https://registry.npmjs.org/@types/node/-/node-10.14.19.tgz",
+ "integrity": "sha512-j6Sqt38ssdMKutXBUuAcmWF8QtHW1Fwz/mz4Y+Wd9mzpBiVFirjpNQf363hG5itkG+yGaD+oiLyb50HxJ36l9Q==",
+ "dev": true
+ },
+ "@types/range-parser": {
+ "version": "1.2.3",
+ "resolved": "https://registry.npmjs.org/@types/range-parser/-/range-parser-1.2.3.tgz",
+ "integrity": "sha512-ewFXqrQHlFsgc09MK5jP5iR7vumV/BYayNC6PgJO2LPe8vrnNFyjQjSppfEngITi0qvfKtzFvgKymGheFM9UOA==",
+ "dev": true
+ },
+ "@types/serve-static": {
+ "version": "1.13.3",
+ "resolved": "https://registry.npmjs.org/@types/serve-static/-/serve-static-1.13.3.tgz",
+ "integrity": "sha512-oprSwp094zOglVrXdlo/4bAHtKTAxX6VT8FOZlBKrmyLbNvE1zxZyJ6yikMVtHIvwP45+ZQGJn+FdXGKTozq0g==",
+ "dev": true,
+ "requires": {
+ "@types/express-serve-static-core": "*",
+ "@types/mime": "*"
+ }
+ },
+ "accepts": {
+ "version": "1.3.7",
+ "resolved": "https://registry.npmjs.org/accepts/-/accepts-1.3.7.tgz",
+ "integrity": "sha512-Il80Qs2WjYlJIBNzNkK6KYqlVMTbZLXgHx2oT0pU/fjRHyEp+PEfEPY0R3WCwAGVOtauxh1hOxNgIf5bv7dQpA==",
+ "dev": true,
+ "requires": {
+ "mime-types": "~2.1.24",
+ "negotiator": "0.6.2"
+ }
+ },
+ "array-flatten": {
+ "version": "1.1.1",
+ "resolved": "https://registry.npmjs.org/array-flatten/-/array-flatten-1.1.1.tgz",
+ "integrity": "sha1-ml9pkFGx5wczKPKgCJaLZOopVdI=",
+ "dev": true
+ },
+ "bintrees": {
+ "version": "1.0.1",
+ "resolved": "https://registry.npmjs.org/bintrees/-/bintrees-1.0.1.tgz",
+ "integrity": "sha1-DmVcm5wkNeqraL9AJyJtK1WjRSQ="
+ },
+ "body-parser": {
+ "version": "1.19.0",
+ "resolved": "https://registry.npmjs.org/body-parser/-/body-parser-1.19.0.tgz",
+ "integrity": "sha512-dhEPs72UPbDnAQJ9ZKMNTP6ptJaionhP5cBb541nXPlW60Jepo9RV/a4fX4XWW9CuFNK22krhrj1+rgzifNCsw==",
+ "dev": true,
+ "requires": {
+ "bytes": "3.1.0",
+ "content-type": "~1.0.4",
+ "debug": "2.6.9",
+ "depd": "~1.1.2",
+ "http-errors": "1.7.2",
+ "iconv-lite": "0.4.24",
+ "on-finished": "~2.3.0",
+ "qs": "6.7.0",
+ "raw-body": "2.4.0",
+ "type-is": "~1.6.17"
+ }
+ },
+ "bytes": {
+ "version": "3.1.0",
+ "resolved": "https://registry.npmjs.org/bytes/-/bytes-3.1.0.tgz",
+ "integrity": "sha512-zauLjrfCG+xvoyaqLoV8bLVXXNGC4JqlxFCutSDWA6fJrTo2ZuvLYTqZ7aHBLZSMOopbzwv8f+wZcVzfVTI2Dg==",
+ "dev": true
+ },
+ "content-disposition": {
+ "version": "0.5.3",
+ "resolved": "https://registry.npmjs.org/content-disposition/-/content-disposition-0.5.3.tgz",
+ "integrity": "sha512-ExO0774ikEObIAEV9kDo50o+79VCUdEB6n6lzKgGwupcVeRlhrj3qGAfwq8G6uBJjkqLrhT0qEYFcWng8z1z0g==",
+ "dev": true,
+ "requires": {
+ "safe-buffer": "5.1.2"
+ }
+ },
+ "content-type": {
+ "version": "1.0.4",
+ "resolved": "https://registry.npmjs.org/content-type/-/content-type-1.0.4.tgz",
+ "integrity": "sha512-hIP3EEPs8tB9AT1L+NUqtwOAps4mk2Zob89MWXMHjHWg9milF/j4osnnQLXBCBFBk/tvIG/tUc9mOUJiPBhPXA==",
+ "dev": true
+ },
+ "cookie": {
+ "version": "0.4.0",
+ "resolved": "https://registry.npmjs.org/cookie/-/cookie-0.4.0.tgz",
+ "integrity": "sha512-+Hp8fLp57wnUSt0tY0tHEXh4voZRDnoIrZPqlo3DPiI4y9lwg/jqx+1Om94/W6ZaPDOUbnjOt/99w66zk+l1Xg==",
+ "dev": true
+ },
+ "cookie-signature": {
+ "version": "1.0.6",
+ "resolved": "https://registry.npmjs.org/cookie-signature/-/cookie-signature-1.0.6.tgz",
+ "integrity": "sha1-4wOogrNCzD7oylE6eZmXNNqzriw=",
+ "dev": true
+ },
+ "debug": {
+ "version": "2.6.9",
+ "resolved": "https://registry.npmjs.org/debug/-/debug-2.6.9.tgz",
+ "integrity": "sha512-bC7ElrdJaJnPbAP+1EotYvqZsb3ecl5wi6Bfi6BJTUcNowp6cvspg0jXznRTKDjm/E7AdgFBVeAPVMNcKGsHMA==",
+ "dev": true,
+ "requires": {
+ "ms": "2.0.0"
+ }
+ },
+ "depd": {
+ "version": "1.1.2",
+ "resolved": "https://registry.npmjs.org/depd/-/depd-1.1.2.tgz",
+ "integrity": "sha1-m81S4UwJd2PnSbJ0xDRu0uVgtak=",
+ "dev": true
+ },
+ "destroy": {
+ "version": "1.0.4",
+ "resolved": "https://registry.npmjs.org/destroy/-/destroy-1.0.4.tgz",
+ "integrity": "sha1-l4hXRCxEdJ5CBmE+N5RiBYJqvYA=",
+ "dev": true
+ },
+ "ee-first": {
+ "version": "1.1.1",
+ "resolved": "https://registry.npmjs.org/ee-first/-/ee-first-1.1.1.tgz",
+ "integrity": "sha1-WQxhFWsK4vTwJVcyoViyZrxWsh0=",
+ "dev": true
+ },
+ "encodeurl": {
+ "version": "1.0.2",
+ "resolved": "https://registry.npmjs.org/encodeurl/-/encodeurl-1.0.2.tgz",
+ "integrity": "sha1-rT/0yG7C0CkyL1oCw6mmBslbP1k=",
+ "dev": true
+ },
+ "escape-html": {
+ "version": "1.0.3",
+ "resolved": "https://registry.npmjs.org/escape-html/-/escape-html-1.0.3.tgz",
+ "integrity": "sha1-Aljq5NPQwJdN4cFpGI7wBR0dGYg=",
+ "dev": true
+ },
+ "etag": {
+ "version": "1.8.1",
+ "resolved": "https://registry.npmjs.org/etag/-/etag-1.8.1.tgz",
+ "integrity": "sha1-Qa4u62XvpiJorr/qg6x9eSmbCIc=",
+ "dev": true
+ },
+ "express": {
+ "version": "4.17.1",
+ "resolved": "https://registry.npmjs.org/express/-/express-4.17.1.tgz",
+ "integrity": "sha512-mHJ9O79RqluphRrcw2X/GTh3k9tVv8YcoyY4Kkh4WDMUYKRZUq0h1o0w2rrrxBqM7VoeUVqgb27xlEMXTnYt4g==",
+ "dev": true,
+ "requires": {
+ "accepts": "~1.3.7",
+ "array-flatten": "1.1.1",
+ "body-parser": "1.19.0",
+ "content-disposition": "0.5.3",
+ "content-type": "~1.0.4",
+ "cookie": "0.4.0",
+ "cookie-signature": "1.0.6",
+ "debug": "2.6.9",
+ "depd": "~1.1.2",
+ "encodeurl": "~1.0.2",
+ "escape-html": "~1.0.3",
+ "etag": "~1.8.1",
+ "finalhandler": "~1.1.2",
+ "fresh": "0.5.2",
+ "merge-descriptors": "1.0.1",
+ "methods": "~1.1.2",
+ "on-finished": "~2.3.0",
+ "parseurl": "~1.3.3",
+ "path-to-regexp": "0.1.7",
+ "proxy-addr": "~2.0.5",
+ "qs": "6.7.0",
+ "range-parser": "~1.2.1",
+ "safe-buffer": "5.1.2",
+ "send": "0.17.1",
+ "serve-static": "1.14.1",
+ "setprototypeof": "1.1.1",
+ "statuses": "~1.5.0",
+ "type-is": "~1.6.18",
+ "utils-merge": "1.0.1",
+ "vary": "~1.1.2"
+ }
+ },
+ "finalhandler": {
+ "version": "1.1.2",
+ "resolved": "https://registry.npmjs.org/finalhandler/-/finalhandler-1.1.2.tgz",
+ "integrity": "sha512-aAWcW57uxVNrQZqFXjITpW3sIUQmHGG3qSb9mUah9MgMC4NeWhNOlNjXEYq3HjRAvL6arUviZGGJsBg6z0zsWA==",
+ "dev": true,
+ "requires": {
+ "debug": "2.6.9",
+ "encodeurl": "~1.0.2",
+ "escape-html": "~1.0.3",
+ "on-finished": "~2.3.0",
+ "parseurl": "~1.3.3",
+ "statuses": "~1.5.0",
+ "unpipe": "~1.0.0"
+ }
+ },
+ "forwarded": {
+ "version": "0.1.2",
+ "resolved": "https://registry.npmjs.org/forwarded/-/forwarded-0.1.2.tgz",
+ "integrity": "sha1-mMI9qxF1ZXuMBXPozszZGw/xjIQ=",
+ "dev": true
+ },
+ "fresh": {
+ "version": "0.5.2",
+ "resolved": "https://registry.npmjs.org/fresh/-/fresh-0.5.2.tgz",
+ "integrity": "sha1-PYyt2Q2XZWn6g1qx+OSyOhBWBac=",
+ "dev": true
+ },
+ "http-errors": {
+ "version": "1.7.2",
+ "resolved": "https://registry.npmjs.org/http-errors/-/http-errors-1.7.2.tgz",
+ "integrity": "sha512-uUQBt3H/cSIVfch6i1EuPNy/YsRSOUBXTVfZ+yR7Zjez3qjBz6i9+i4zjNaoqcoFVI4lQJ5plg63TvGfRSDCRg==",
+ "dev": true,
+ "requires": {
+ "depd": "~1.1.2",
+ "inherits": "2.0.3",
+ "setprototypeof": "1.1.1",
+ "statuses": ">= 1.5.0 < 2",
+ "toidentifier": "1.0.0"
+ }
+ },
+ "iconv-lite": {
+ "version": "0.4.24",
+ "resolved": "https://registry.npmjs.org/iconv-lite/-/iconv-lite-0.4.24.tgz",
+ "integrity": "sha512-v3MXnZAcvnywkTUEZomIActle7RXXeedOR31wwl7VlyoXO4Qi9arvSenNQWne1TcRwhCL1HwLI21bEqdpj8/rA==",
+ "dev": true,
+ "requires": {
+ "safer-buffer": ">= 2.1.2 < 3"
+ }
+ },
+ "inherits": {
+ "version": "2.0.3",
+ "resolved": "https://registry.npmjs.org/inherits/-/inherits-2.0.3.tgz",
+ "integrity": "sha1-Yzwsg+PaQqUC9SRmAiSA9CCCYd4=",
+ "dev": true
+ },
+ "ipaddr.js": {
+ "version": "1.9.0",
+ "resolved": "https://registry.npmjs.org/ipaddr.js/-/ipaddr.js-1.9.0.tgz",
+ "integrity": "sha512-M4Sjn6N/+O6/IXSJseKqHoFc+5FdGJ22sXqnjTpdZweHK64MzEPAyQZyEU3R/KRv2GLoa7nNtg/C2Ev6m7z+eA==",
+ "dev": true
+ },
+ "media-typer": {
+ "version": "0.3.0",
+ "resolved": "https://registry.npmjs.org/media-typer/-/media-typer-0.3.0.tgz",
+ "integrity": "sha1-hxDXrwqmJvj/+hzgAWhUUmMlV0g=",
+ "dev": true
+ },
+ "merge-descriptors": {
+ "version": "1.0.1",
+ "resolved": "https://registry.npmjs.org/merge-descriptors/-/merge-descriptors-1.0.1.tgz",
+ "integrity": "sha1-sAqqVW3YtEVoFQ7J0blT8/kMu2E=",
+ "dev": true
+ },
+ "methods": {
+ "version": "1.1.2",
+ "resolved": "https://registry.npmjs.org/methods/-/methods-1.1.2.tgz",
+ "integrity": "sha1-VSmk1nZUE07cxSZmVoNbD4Ua/O4=",
+ "dev": true
+ },
+ "mime": {
+ "version": "1.6.0",
+ "resolved": "https://registry.npmjs.org/mime/-/mime-1.6.0.tgz",
+ "integrity": "sha512-x0Vn8spI+wuJ1O6S7gnbaQg8Pxh4NNHb7KSINmEWKiPE4RKOplvijn+NkmYmmRgP68mc70j2EbeTFRsrswaQeg==",
+ "dev": true
+ },
+ "mime-db": {
+ "version": "1.40.0",
+ "resolved": "https://registry.npmjs.org/mime-db/-/mime-db-1.40.0.tgz",
+ "integrity": "sha512-jYdeOMPy9vnxEqFRRo6ZvTZ8d9oPb+k18PKoYNYUe2stVEBPPwsln/qWzdbmaIvnhZ9v2P+CuecK+fpUfsV2mA==",
+ "dev": true
+ },
+ "mime-types": {
+ "version": "2.1.24",
+ "resolved": "https://registry.npmjs.org/mime-types/-/mime-types-2.1.24.tgz",
+ "integrity": "sha512-WaFHS3MCl5fapm3oLxU4eYDw77IQM2ACcxQ9RIxfaC3ooc6PFuBMGZZsYpvoXS5D5QTWPieo1jjLdAm3TBP3cQ==",
+ "dev": true,
+ "requires": {
+ "mime-db": "1.40.0"
+ }
+ },
+ "ms": {
+ "version": "2.0.0",
+ "resolved": "https://registry.npmjs.org/ms/-/ms-2.0.0.tgz",
+ "integrity": "sha1-VgiurfwAvmwpAd9fmGF4jeDVl8g=",
+ "dev": true
+ },
+ "negotiator": {
+ "version": "0.6.2",
+ "resolved": "https://registry.npmjs.org/negotiator/-/negotiator-0.6.2.tgz",
+ "integrity": "sha512-hZXc7K2e+PgeI1eDBe/10Ard4ekbfrrqG8Ep+8Jmf4JID2bNg7NvCPOZN+kfF574pFQI7mum2AUqDidoKqcTOw==",
+ "dev": true
+ },
+ "on-finished": {
+ "version": "2.3.0",
+ "resolved": "https://registry.npmjs.org/on-finished/-/on-finished-2.3.0.tgz",
+ "integrity": "sha1-IPEzZIGwg811M3mSoWlxqi2QaUc=",
+ "dev": true,
+ "requires": {
+ "ee-first": "1.1.1"
+ }
+ },
+ "p-event": {
+ "version": "4.1.0",
+ "resolved": "https://registry.npmjs.org/p-event/-/p-event-4.1.0.tgz",
+ "integrity": "sha512-4vAd06GCsgflX4wHN1JqrMzBh/8QZ4j+rzp0cd2scXRwuBEv+QR3wrVA5aLhWDLw4y2WgDKvzWF3CCLmVM1UgA==",
+ "dev": true,
+ "requires": {
+ "p-timeout": "^2.0.1"
+ }
+ },
+ "p-finally": {
+ "version": "1.0.0",
+ "resolved": "https://registry.npmjs.org/p-finally/-/p-finally-1.0.0.tgz",
+ "integrity": "sha1-P7z7FbiZpEEjs0ttzBi3JDNqLK4=",
+ "dev": true
+ },
+ "p-timeout": {
+ "version": "2.0.1",
+ "resolved": "https://registry.npmjs.org/p-timeout/-/p-timeout-2.0.1.tgz",
+ "integrity": "sha512-88em58dDVB/KzPEx1X0N3LwFfYZPyDc4B6eF38M1rk9VTZMbxXXgjugz8mmwpS9Ox4BDZ+t6t3QP5+/gazweIA==",
+ "dev": true,
+ "requires": {
+ "p-finally": "^1.0.0"
+ }
+ },
+ "parseurl": {
+ "version": "1.3.3",
+ "resolved": "https://registry.npmjs.org/parseurl/-/parseurl-1.3.3.tgz",
+ "integrity": "sha512-CiyeOxFT/JZyN5m0z9PfXw4SCBJ6Sygz1Dpl0wqjlhDEGGBP1GnsUVEL0p63hoG1fcj3fHynXi9NYO4nWOL+qQ==",
+ "dev": true
+ },
+ "path-to-regexp": {
+ "version": "0.1.7",
+ "resolved": "https://registry.npmjs.org/path-to-regexp/-/path-to-regexp-0.1.7.tgz",
+ "integrity": "sha1-32BBeABfUi8V60SQ5yR6G/qmf4w=",
+ "dev": true
+ },
+ "prom-client": {
+ "version": "11.5.3",
+ "resolved": "https://registry.npmjs.org/prom-client/-/prom-client-11.5.3.tgz",
+ "integrity": "sha512-iz22FmTbtkyL2vt0MdDFY+kWof+S9UB/NACxSn2aJcewtw+EERsen0urSkZ2WrHseNdydsvcxCTAnPcSMZZv4Q==",
+ "requires": {
+ "tdigest": "^0.1.1"
+ }
+ },
+ "proxy-addr": {
+ "version": "2.0.5",
+ "resolved": "https://registry.npmjs.org/proxy-addr/-/proxy-addr-2.0.5.tgz",
+ "integrity": "sha512-t/7RxHXPH6cJtP0pRG6smSr9QJidhB+3kXu0KgXnbGYMgzEnUxRQ4/LDdfOwZEMyIh3/xHb8PX3t+lfL9z+YVQ==",
+ "dev": true,
+ "requires": {
+ "forwarded": "~0.1.2",
+ "ipaddr.js": "1.9.0"
+ }
+ },
+ "qs": {
+ "version": "6.7.0",
+ "resolved": "https://registry.npmjs.org/qs/-/qs-6.7.0.tgz",
+ "integrity": "sha512-VCdBRNFTX1fyE7Nb6FYoURo/SPe62QCaAyzJvUjwRaIsc+NePBEniHlvxFmmX56+HZphIGtV0XeCirBtpDrTyQ==",
+ "dev": true
+ },
+ "range-parser": {
+ "version": "1.2.1",
+ "resolved": "https://registry.npmjs.org/range-parser/-/range-parser-1.2.1.tgz",
+ "integrity": "sha512-Hrgsx+orqoygnmhFbKaHE6c296J+HTAQXoxEF6gNupROmmGJRoyzfG3ccAveqCBrwr/2yxQ5BVd/GTl5agOwSg==",
+ "dev": true
+ },
+ "raw-body": {
+ "version": "2.4.0",
+ "resolved": "https://registry.npmjs.org/raw-body/-/raw-body-2.4.0.tgz",
+ "integrity": "sha512-4Oz8DUIwdvoa5qMJelxipzi/iJIi40O5cGV1wNYp5hvZP8ZN0T+jiNkL0QepXs+EsQ9XJ8ipEDoiH70ySUJP3Q==",
+ "dev": true,
+ "requires": {
+ "bytes": "3.1.0",
+ "http-errors": "1.7.2",
+ "iconv-lite": "0.4.24",
+ "unpipe": "1.0.0"
+ }
+ },
+ "safe-buffer": {
+ "version": "5.1.2",
+ "resolved": "https://registry.npmjs.org/safe-buffer/-/safe-buffer-5.1.2.tgz",
+ "integrity": "sha512-Gd2UZBJDkXlY7GbJxfsE8/nvKkUEU1G38c1siN6QP6a9PT9MmHB8GnpscSmMJSoF8LOIrt8ud/wPtojys4G6+g==",
+ "dev": true
+ },
+ "safer-buffer": {
+ "version": "2.1.2",
+ "resolved": "https://registry.npmjs.org/safer-buffer/-/safer-buffer-2.1.2.tgz",
+ "integrity": "sha512-YZo3K82SD7Riyi0E1EQPojLz7kpepnSQI9IyPbHHg1XXXevb5dJI7tpyN2ADxGcQbHG7vcyRHk0cbwqcQriUtg==",
+ "dev": true
+ },
+ "send": {
+ "version": "0.17.1",
+ "resolved": "https://registry.npmjs.org/send/-/send-0.17.1.tgz",
+ "integrity": "sha512-BsVKsiGcQMFwT8UxypobUKyv7irCNRHk1T0G680vk88yf6LBByGcZJOTJCrTP2xVN6yI+XjPJcNuE3V4fT9sAg==",
+ "dev": true,
+ "requires": {
+ "debug": "2.6.9",
+ "depd": "~1.1.2",
+ "destroy": "~1.0.4",
+ "encodeurl": "~1.0.2",
+ "escape-html": "~1.0.3",
+ "etag": "~1.8.1",
+ "fresh": "0.5.2",
+ "http-errors": "~1.7.2",
+ "mime": "1.6.0",
+ "ms": "2.1.1",
+ "on-finished": "~2.3.0",
+ "range-parser": "~1.2.1",
+ "statuses": "~1.5.0"
+ },
+ "dependencies": {
+ "ms": {
+ "version": "2.1.1",
+ "resolved": "https://registry.npmjs.org/ms/-/ms-2.1.1.tgz",
+ "integrity": "sha512-tgp+dl5cGk28utYktBsrFqA7HKgrhgPsg6Z/EfhWI4gl1Hwq8B/GmY/0oXZ6nF8hDVesS/FpnYaD/kOWhYQvyg==",
+ "dev": true
+ }
+ }
+ },
+ "serve-static": {
+ "version": "1.14.1",
+ "resolved": "https://registry.npmjs.org/serve-static/-/serve-static-1.14.1.tgz",
+ "integrity": "sha512-JMrvUwE54emCYWlTI+hGrGv5I8dEwmco/00EvkzIIsR7MqrHonbD9pO2MOfFnpFntl7ecpZs+3mW+XbQZu9QCg==",
+ "dev": true,
+ "requires": {
+ "encodeurl": "~1.0.2",
+ "escape-html": "~1.0.3",
+ "parseurl": "~1.3.3",
+ "send": "0.17.1"
+ }
+ },
+ "setprototypeof": {
+ "version": "1.1.1",
+ "resolved": "https://registry.npmjs.org/setprototypeof/-/setprototypeof-1.1.1.tgz",
+ "integrity": "sha512-JvdAWfbXeIGaZ9cILp38HntZSFSo3mWg6xGcJJsd+d4aRMOqauag1C63dJfDw7OaMYwEbHMOxEZ1lqVRYP2OAw==",
+ "dev": true
+ },
+ "statuses": {
+ "version": "1.5.0",
+ "resolved": "https://registry.npmjs.org/statuses/-/statuses-1.5.0.tgz",
+ "integrity": "sha1-Fhx9rBd2Wf2YEfQ3cfqZOBR4Yow=",
+ "dev": true
+ },
+ "tdigest": {
+ "version": "0.1.1",
+ "resolved": "https://registry.npmjs.org/tdigest/-/tdigest-0.1.1.tgz",
+ "integrity": "sha1-Ljyyw56kSeVdHmzZEReszKRYgCE=",
+ "requires": {
+ "bintrees": "1.0.1"
+ }
+ },
+ "toidentifier": {
+ "version": "1.0.0",
+ "resolved": "https://registry.npmjs.org/toidentifier/-/toidentifier-1.0.0.tgz",
+ "integrity": "sha512-yaOH/Pk/VEhBWWTlhI+qXxDFXlejDGcQipMlyxda9nthulaxLZUNcUqFxokp0vcYnvteJln5FNQDRrxj3YcbVw==",
+ "dev": true
+ },
+ "type-is": {
+ "version": "1.6.18",
+ "resolved": "https://registry.npmjs.org/type-is/-/type-is-1.6.18.tgz",
+ "integrity": "sha512-TkRKr9sUTxEH8MdfuCSP7VizJyzRNMjj2J2do2Jr3Kym598JVdEksuzPQCnlFPW4ky9Q+iA+ma9BGm06XQBy8g==",
+ "dev": true,
+ "requires": {
+ "media-typer": "0.3.0",
+ "mime-types": "~2.1.24"
+ }
+ },
+ "unpipe": {
+ "version": "1.0.0",
+ "resolved": "https://registry.npmjs.org/unpipe/-/unpipe-1.0.0.tgz",
+ "integrity": "sha1-sr9O6FFKrmFltIF4KdIbLvSZBOw=",
+ "dev": true
+ },
+ "utils-merge": {
+ "version": "1.0.1",
+ "resolved": "https://registry.npmjs.org/utils-merge/-/utils-merge-1.0.1.tgz",
+ "integrity": "sha1-n5VxD1CiZ5R7LMwSR0HBAoQn5xM=",
+ "dev": true
+ },
+ "vary": {
+ "version": "1.1.2",
+ "resolved": "https://registry.npmjs.org/vary/-/vary-1.1.2.tgz",
+ "integrity": "sha1-IpnwLG3tMNSllhsLn3RSShj2NPw=",
+ "dev": true
+ }
+ }
+}
diff --git a/extensions/metrics/package.json b/extensions/metrics/package.json
new file mode 100644
index 000000000000..61e0488065f2
--- /dev/null
+++ b/extensions/metrics/package.json
@@ -0,0 +1,56 @@
+{
+ "name": "@loopback/extension-metrics",
+ "version": "0.0.1",
+ "description": "LoopBack Metrics for Prometheus",
+ "engines": {
+ "node": ">=8.9"
+ },
+ "scripts": {
+ "build": "lb-tsc",
+ "clean": "lb-clean loopback-extension-metrics*.tgz dist tsconfig.build.tsbuildinfo package",
+ "pretest": "npm run build",
+ "test": "lb-mocha \"dist/__tests__/**/*.js\"",
+ "verify": "npm pack && tar xf loopback-extension-metrics*.tgz && tree package && npm run clean"
+ },
+ "author": "IBM Corp.",
+ "copyright.owner": "IBM Corp.",
+ "license": "MIT",
+ "dependencies": {
+ "@loopback/context": "^1.23.3",
+ "@loopback/core": "^1.10.5",
+ "@loopback/rest": "^1.21.0",
+ "prom-client": "^11.5.3"
+ },
+ "devDependencies": {
+ "@loopback/build": "^2.0.14",
+ "@loopback/eslint-config": "^4.1.2",
+ "@loopback/testlab": "^1.9.2",
+ "@types/express": "^4.17.1",
+ "@types/node": "^10.14.18",
+ "express": "^4.17.1",
+ "p-event": "^4.1.0"
+ },
+ "keywords": [
+ "LoopBack",
+ "Cloud Native",
+ "Prometheus",
+ "Metrics"
+ ],
+ "files": [
+ "README.md",
+ "index.js",
+ "index.d.ts",
+ "dist",
+ "src",
+ "!*/__tests__",
+ "templates"
+ ],
+ "publishConfig": {
+ "access": "public"
+ },
+ "repository": {
+ "type": "git",
+ "url": "https://github.com/strongloop/loopback-next.git",
+ "directory": "extensions/metrics"
+ }
+}
diff --git a/extensions/metrics/prometheus-demo.png b/extensions/metrics/prometheus-demo.png
new file mode 100644
index 000000000000..fe8c643786d7
Binary files /dev/null and b/extensions/metrics/prometheus-demo.png differ
diff --git a/extensions/metrics/src/__tests__/acceptance/metrics-push.acceptance.ts b/extensions/metrics/src/__tests__/acceptance/metrics-push.acceptance.ts
new file mode 100644
index 000000000000..d72ded8ea9bf
--- /dev/null
+++ b/extensions/metrics/src/__tests__/acceptance/metrics-push.acceptance.ts
@@ -0,0 +1,60 @@
+// Copyright IBM Corp. 2019. All Rights Reserved.
+// Node module: @loopback/extension-metrics
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+import {RestApplication, RestServerConfig} from '@loopback/rest';
+import {givenHttpServerConfig, supertest} from '@loopback/testlab';
+import {AddressInfo} from 'net';
+import {promisify} from 'util';
+import {MetricsBindings, MetricsComponent, MetricsOptions} from '../..';
+import {PushGateway} from './mock-pushgateway';
+
+const gateway = new PushGateway();
+
+describe('Metrics (with push gateway)', function() {
+ let gwUrl: string;
+ before(async () => {
+ const server = await gateway.start(0);
+ const port = (server.address() as AddressInfo).port;
+ gwUrl = `http://127.0.0.1:${port}`;
+ });
+
+ after(async () => {
+ return gateway.stop();
+ });
+
+ let app: RestApplication;
+
+ afterEach(async () => {
+ if (app) await app.stop();
+ (app as unknown) = undefined;
+ });
+
+ beforeEach(async () => {
+ await givenAppWithCustomConfig({
+ // Push metrics each 10 ms
+ pushGateway: {url: gwUrl, interval: 10},
+ });
+ });
+
+ it('pushes metrics to gateway', async () => {
+ // Wait for 100 ms
+ await promisify(setTimeout)(50);
+ const request = supertest(gwUrl);
+ // Now we expect to get LoopBack metrics from the push gateway
+ await request.get('/metrics').expect(200, /job="loopback"/);
+ });
+
+ async function givenAppWithCustomConfig(config: MetricsOptions) {
+ app = givenRestApplication();
+ app.configure(MetricsBindings.COMPONENT).to(config);
+ app.component(MetricsComponent);
+ await app.start();
+ }
+
+ function givenRestApplication(config?: RestServerConfig) {
+ const rest = Object.assign({}, givenHttpServerConfig(), config);
+ return new RestApplication({rest});
+ }
+});
diff --git a/extensions/metrics/src/__tests__/acceptance/metrics.acceptance.ts b/extensions/metrics/src/__tests__/acceptance/metrics.acceptance.ts
new file mode 100644
index 000000000000..469bf6e835f3
--- /dev/null
+++ b/extensions/metrics/src/__tests__/acceptance/metrics.acceptance.ts
@@ -0,0 +1,101 @@
+// Copyright IBM Corp. 2019. All Rights Reserved.
+// Node module: @loopback/extension-metrics
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+import {RestApplication, RestServerConfig} from '@loopback/rest';
+import {
+ Client,
+ createRestAppClient,
+ expect,
+ givenHttpServerConfig,
+} from '@loopback/testlab';
+import {MetricsBindings, MetricsComponent, MetricsOptions} from '../..';
+
+describe('Metrics (acceptance)', () => {
+ let app: RestApplication;
+ let request: Client;
+
+ afterEach(async () => {
+ if (app) await app.stop();
+ (app as unknown) = undefined;
+ });
+
+ context('with default config', () => {
+ beforeEach(async () => {
+ app = givenRestApplication();
+ app.component(MetricsComponent);
+ await app.start();
+ request = createRestAppClient(app);
+ });
+
+ it('exposes metrics at "/metrics/"', async () => {
+ const res = await request
+ .get('/metrics')
+ .expect(200)
+ .expect('content-type', /text/);
+ expect(res.text).to.match(/# TYPE/);
+ expect(res.text).to.match(/# HELP/);
+ });
+ });
+
+ context('with custom defaultMetrics', () => {
+ it('honors prefix', async () => {
+ await givenAppWithCustomConfig({
+ defaultMetrics: {
+ // `-` is not allowed
+ prefix: 'myapp_',
+ },
+ });
+ await request
+ .get('/metrics')
+ .expect(200)
+ .expect('content-type', /text/);
+ });
+ });
+
+ context('with custom endpoint basePath', () => {
+ it('honors prefix', async () => {
+ await givenAppWithCustomConfig({
+ endpoint: {
+ basePath: '/internal/metrics',
+ },
+ });
+ await request
+ .get('/internal/metrics')
+ .expect(200)
+ .expect('content-type', /text/);
+ await request.get('/metrics').expect(404);
+ });
+ });
+
+ context('with defaultMetrics disabled', () => {
+ it('does not emit default metrics', async () => {
+ await givenAppWithCustomConfig({
+ defaultMetrics: {
+ disabled: true,
+ },
+ });
+ const res = await request
+ .get('/metrics')
+ .expect(200)
+ .expect('content-type', /text/);
+ expect(res.text).to.not.match(
+ /# TYPE process_cpu_user_seconds_total counter/,
+ );
+ });
+ });
+
+ async function givenAppWithCustomConfig(config: MetricsOptions) {
+ app = givenRestApplication();
+ app.configure(MetricsBindings.COMPONENT).to(config);
+ app.component(MetricsComponent);
+ await app.start();
+ request = createRestAppClient(app);
+ }
+
+ function givenRestApplication(config?: RestServerConfig) {
+ const rest = Object.assign({}, givenHttpServerConfig(), config);
+ return new RestApplication({rest});
+ }
+});
diff --git a/extensions/metrics/src/__tests__/acceptance/mock-pushgateway.ts b/extensions/metrics/src/__tests__/acceptance/mock-pushgateway.ts
new file mode 100644
index 000000000000..9aa2f8c18cb9
--- /dev/null
+++ b/extensions/metrics/src/__tests__/acceptance/mock-pushgateway.ts
@@ -0,0 +1,45 @@
+// Copyright IBM Corp. 2019. All Rights Reserved.
+// Node module: @loopback/extension-metrics
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+import * as express from 'express';
+import {Server} from 'http';
+import pEvent from 'p-event';
+
+/**
+ * A mockup server for https://github.com/prometheus/pushgateway
+ */
+export class PushGateway {
+ private server?: Server;
+ private metrics: string[] = [];
+
+ async start(port = 9091) {
+ const app = express();
+ // A hack to force content-type to be `text/plain` as prom-client does not
+ // set `Content-Type` header
+ app.use((req, res, next) => {
+ req.headers['content-type'] = 'text/plain';
+ next();
+ });
+ app.use(express.text({type: '*/*'}));
+ app.get('/metrics', (req, res) => {
+ res.send(this.metrics.join('\n'));
+ });
+
+ app.post('/metrics/job/:jobName', (req, res) => {
+ this.metrics.push(`job="${req.params.jobName}"\n${req.body}`);
+ res.send('\n');
+ });
+ this.server = app.listen(port);
+ await pEvent(this.server, 'listening');
+ return this.server;
+ }
+
+ async stop() {
+ if (!this.server) return;
+ this.server.close();
+ await pEvent(this.server, 'close');
+ this.server = undefined;
+ }
+}
diff --git a/extensions/metrics/src/controllers/index.ts b/extensions/metrics/src/controllers/index.ts
new file mode 100644
index 000000000000..ae52c9f35f3d
--- /dev/null
+++ b/extensions/metrics/src/controllers/index.ts
@@ -0,0 +1,6 @@
+// Copyright IBM Corp. 2019. All Rights Reserved.
+// Node module: @loopback/extension-metrics
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+export * from './metrics.controller';
diff --git a/extensions/metrics/src/controllers/metrics.controller.ts b/extensions/metrics/src/controllers/metrics.controller.ts
new file mode 100644
index 000000000000..99dc1f5e3cd5
--- /dev/null
+++ b/extensions/metrics/src/controllers/metrics.controller.ts
@@ -0,0 +1,28 @@
+// Copyright IBM Corp. 2019. All Rights Reserved.
+// Node module: @loopback/extension-metrics
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+import {bind, BindingScope, Constructor, inject} from '@loopback/core';
+import {get, Response, RestBindings} from '@loopback/rest';
+import {register} from 'prom-client';
+
+export function metricsControllerFactory(
+ basePath = '/metrics',
+): Constructor {
+ @bind({scope: BindingScope.SINGLETON})
+ class MetricsController {
+ @get(basePath, {
+ responses: {},
+ 'x-visibility': 'undocumented',
+ })
+ report(@inject(RestBindings.Http.RESPONSE) res: Response) {
+ // Set the content type from the register
+ res.contentType(register.contentType);
+ res.send(register.metrics());
+ return res;
+ }
+ }
+
+ return MetricsController;
+}
diff --git a/extensions/metrics/src/index.ts b/extensions/metrics/src/index.ts
new file mode 100644
index 000000000000..6eb8e3e1c197
--- /dev/null
+++ b/extensions/metrics/src/index.ts
@@ -0,0 +1,9 @@
+// Copyright IBM Corp. 2019. All Rights Reserved.
+// Node module: @loopback/extension-metrics
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+export * from 'prom-client';
+export * from './keys';
+export * from './metrics.component';
+export * from './types';
diff --git a/extensions/metrics/src/interceptors/index.ts b/extensions/metrics/src/interceptors/index.ts
new file mode 100644
index 000000000000..40b9b7a34f31
--- /dev/null
+++ b/extensions/metrics/src/interceptors/index.ts
@@ -0,0 +1,6 @@
+// Copyright IBM Corp. 2019. All Rights Reserved.
+// Node module: @loopback/extension-metrics
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+export * from './metrics.interceptor';
diff --git a/extensions/metrics/src/interceptors/metrics.interceptor.ts b/extensions/metrics/src/interceptors/metrics.interceptor.ts
new file mode 100644
index 000000000000..ced0bd759a01
--- /dev/null
+++ b/extensions/metrics/src/interceptors/metrics.interceptor.ts
@@ -0,0 +1,95 @@
+// Copyright IBM Corp. 2019. All Rights Reserved.
+// Node module: @loopback/extension-metrics
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+import {
+ asGlobalInterceptor,
+ bind,
+ BindingScope,
+ Interceptor,
+ InvocationContext,
+ Provider,
+ ValueOrPromise,
+} from '@loopback/context';
+import {Counter, Gauge, Histogram, register, Summary} from 'prom-client';
+
+/**
+ * This interceptor captures metrics for method invocations,
+ * excluding sequence actions and middleware executed before
+ * a method is invoked. Please collect metrics at other places
+ * if you want to cover more than just method invocations.
+ */
+@bind(asGlobalInterceptor('metrics'), {scope: BindingScope.SINGLETON})
+export class MetricsInterceptor implements Provider {
+ private static gauge: Gauge;
+
+ private static histogram: Histogram;
+
+ private static counter: Counter;
+
+ private static summary: Summary;
+
+ private static setup() {
+ // Check if the gauge is registered
+ if (
+ this.gauge &&
+ register.getSingleMetric('loopback_invocation_duration_seconds')
+ )
+ return;
+ // The constructor will register the metric with the global registry
+ this.gauge = new Gauge({
+ name: 'loopback_invocation_duration_seconds',
+ help: 'method invocation',
+ labelNames: ['targetName'],
+ });
+
+ this.histogram = new Histogram({
+ name: 'loopback_invocation_duration_histogram',
+ help: 'method invocation histogram',
+ labelNames: ['targetName'],
+ });
+
+ this.counter = new Counter({
+ name: 'loopback_invocation_total',
+ help: 'method invocation counts',
+ labelNames: ['targetName'],
+ });
+
+ this.summary = new Summary({
+ name: 'loopback_invocation_duration_summary',
+ help: 'method invocation summary',
+ labelNames: ['targetName'],
+ });
+ }
+
+ constructor() {}
+
+ value() {
+ return this.intercept.bind(this);
+ }
+
+ async intercept(
+ invocationCtx: InvocationContext,
+ next: () => ValueOrPromise,
+ ) {
+ MetricsInterceptor.setup();
+ const endGauge = MetricsInterceptor.gauge.startTimer({
+ targetName: invocationCtx.targetName,
+ });
+ const endHistogram = MetricsInterceptor.histogram.startTimer({
+ targetName: invocationCtx.targetName,
+ });
+ const endSummary = MetricsInterceptor.summary.startTimer({
+ targetName: invocationCtx.targetName,
+ });
+ try {
+ MetricsInterceptor.counter.inc();
+ return await next();
+ } finally {
+ endGauge();
+ endHistogram();
+ endSummary();
+ }
+ }
+}
diff --git a/extensions/metrics/src/keys.ts b/extensions/metrics/src/keys.ts
new file mode 100644
index 000000000000..303ce893094e
--- /dev/null
+++ b/extensions/metrics/src/keys.ts
@@ -0,0 +1,17 @@
+// Copyright IBM Corp. 2019. All Rights Reserved.
+// Node module: @loopback/extension-metrics
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+import {BindingKey} from '@loopback/context';
+import {CoreBindings} from '@loopback/core';
+import {MetricsComponent} from './metrics.component';
+
+/**
+ * Binding keys used by this component.
+ */
+export namespace MetricsBindings {
+ export const COMPONENT = BindingKey.create(
+ `${CoreBindings.COMPONENTS}.MetricsComponent`,
+ );
+}
diff --git a/extensions/metrics/src/metrics.component.ts b/extensions/metrics/src/metrics.component.ts
new file mode 100644
index 000000000000..6e521122976e
--- /dev/null
+++ b/extensions/metrics/src/metrics.component.ts
@@ -0,0 +1,51 @@
+// Copyright IBM Corp. 2019. All Rights Reserved.
+// Node module: @loopback/extension-metrics
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+import {
+ bind,
+ // eslint-disable-next-line @typescript-eslint/no-unused-vars
+ config,
+ ContextTags,
+ createBindingFromClass,
+ inject,
+} from '@loopback/context';
+import {Application, Component, CoreBindings} from '@loopback/core';
+import {metricsControllerFactory} from './controllers';
+import {MetricsInterceptor} from './interceptors';
+import {MetricsBindings} from './keys';
+import {MetricsObserver, MetricsPushObserver} from './observers';
+import {DEFAULT_METRICS_OPTIONS, MetricsOptions} from './types';
+
+/**
+ * A component providing metrics for Prometheus
+ */
+@bind({tags: {[ContextTags.KEY]: MetricsBindings.COMPONENT}})
+export class MetricsComponent implements Component {
+ constructor(
+ @inject(CoreBindings.APPLICATION_INSTANCE)
+ private application: Application,
+ @config()
+ options: MetricsOptions = DEFAULT_METRICS_OPTIONS,
+ ) {
+ if (
+ !options.defaultMetrics ||
+ (options.defaultMetrics && !options.defaultMetrics.disabled)
+ ) {
+ this.application.lifeCycleObserver(MetricsObserver);
+ }
+ if (
+ !options.pushGateway ||
+ (options.pushGateway && !options.pushGateway.disabled)
+ ) {
+ this.application.lifeCycleObserver(MetricsPushObserver);
+ }
+ this.application.add(createBindingFromClass(MetricsInterceptor));
+ if (!options.endpoint || (options.endpoint && !options.endpoint.disabled)) {
+ this.application.controller(
+ metricsControllerFactory(options.endpoint && options.endpoint.basePath),
+ );
+ }
+ }
+}
diff --git a/extensions/metrics/src/observers/index.ts b/extensions/metrics/src/observers/index.ts
new file mode 100644
index 000000000000..ed69679e9a98
--- /dev/null
+++ b/extensions/metrics/src/observers/index.ts
@@ -0,0 +1,7 @@
+// Copyright IBM Corp. 2019. All Rights Reserved.
+// Node module: @loopback/extension-metrics
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+export * from './metrics.observer';
+export * from './metrics.push.observer';
diff --git a/extensions/metrics/src/observers/metrics.observer.ts b/extensions/metrics/src/observers/metrics.observer.ts
new file mode 100644
index 000000000000..aec0669dff0a
--- /dev/null
+++ b/extensions/metrics/src/observers/metrics.observer.ts
@@ -0,0 +1,34 @@
+// Copyright IBM Corp. 2019. All Rights Reserved.
+// Node module: @loopback/extension-metrics
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+import {config, LifeCycleObserver} from '@loopback/core';
+import {collectDefaultMetrics, register} from 'prom-client';
+import {MetricsBindings} from '../keys';
+import {DEFAULT_METRICS_OPTIONS, MetricsOptions} from '../types';
+
+/**
+ * An observer to set default Node.js metrics collection
+ */
+export class MetricsObserver implements LifeCycleObserver {
+ private interval: NodeJS.Timeout | undefined;
+
+ constructor(
+ @config({fromBinding: MetricsBindings.COMPONENT})
+ private options: MetricsOptions = DEFAULT_METRICS_OPTIONS,
+ ) {}
+
+ start() {
+ const defaultMetricsConfig = this.options.defaultMetrics;
+ this.interval = collectDefaultMetrics(defaultMetricsConfig);
+ }
+
+ stop() {
+ if (this.interval) {
+ clearInterval(this.interval);
+ this.interval = undefined;
+ register.clear();
+ }
+ }
+}
diff --git a/extensions/metrics/src/observers/metrics.push.observer.ts b/extensions/metrics/src/observers/metrics.push.observer.ts
new file mode 100644
index 000000000000..c14f2bd4e4c3
--- /dev/null
+++ b/extensions/metrics/src/observers/metrics.push.observer.ts
@@ -0,0 +1,38 @@
+// Copyright IBM Corp. 2019. All Rights Reserved.
+// Node module: @loopback/extension-metrics
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+import {config, LifeCycleObserver} from '@loopback/core';
+import {Pushgateway} from 'prom-client';
+import {MetricsBindings} from '../keys';
+import {DEFAULT_METRICS_OPTIONS, MetricsOptions} from '../types';
+
+/**
+ * An observer to set up periodical push of metrics to a push gateway
+ */
+export class MetricsPushObserver implements LifeCycleObserver {
+ private interval: NodeJS.Timeout | undefined;
+ private gateway: Pushgateway;
+
+ constructor(
+ @config({fromBinding: MetricsBindings.COMPONENT})
+ private options: MetricsOptions = DEFAULT_METRICS_OPTIONS,
+ ) {}
+
+ start() {
+ const gwConfig = this.options.pushGateway;
+ if (!gwConfig) return;
+ this.gateway = new Pushgateway(gwConfig.url);
+ this.interval = setInterval(() => {
+ this.gateway.pushAdd({jobName: 'loopback'}, () => {});
+ }, gwConfig.interval || 5000);
+ }
+
+ stop() {
+ if (this.interval) {
+ clearInterval(this.interval);
+ this.interval = undefined;
+ }
+ }
+}
diff --git a/extensions/metrics/src/types.ts b/extensions/metrics/src/types.ts
new file mode 100644
index 000000000000..5df3d8241c1c
--- /dev/null
+++ b/extensions/metrics/src/types.ts
@@ -0,0 +1,32 @@
+// Copyright IBM Corp. 2019. All Rights Reserved.
+// Node module: @loopback/extension-metrics
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+import {DefaultMetricsCollectorConfiguration} from 'prom-client';
+
+export interface MetricsOptions {
+ endpoint?: {
+ disabled?: boolean;
+ basePath?: string;
+ };
+
+ defaultMetrics?: {
+ disabled?: boolean;
+ } & DefaultMetricsCollectorConfiguration;
+
+ pushGateway?: {
+ disabled?: boolean;
+ url: string;
+ interval?: number;
+ };
+}
+
+export const DEFAULT_METRICS_OPTIONS: MetricsOptions = {
+ endpoint: {
+ basePath: '/metrics',
+ },
+ defaultMetrics: {
+ timeout: 5000,
+ },
+};
diff --git a/extensions/metrics/tsconfig.build.json b/extensions/metrics/tsconfig.build.json
new file mode 100644
index 000000000000..c7b8e49eaca5
--- /dev/null
+++ b/extensions/metrics/tsconfig.build.json
@@ -0,0 +1,9 @@
+{
+ "$schema": "http://json.schemastore.org/tsconfig",
+ "extends": "@loopback/build/config/tsconfig.common.json",
+ "compilerOptions": {
+ "outDir": "dist",
+ "rootDir": "src"
+ },
+ "include": ["src"]
+}