http-graceful-shutdown
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Gracefully shuts down node.js http server. More than 10 Mio downloads overall.
Version 3.0 just released. This version is fully backwards compatible to version 2.x but adds much better handling under the hood. More that 10 Mio downloads.
- can be used with express, koa, fastify, native node http, http2 ... see examples
- simple to use
- configurable to your needs
- add your own cleanup function
Features
http-graceful-shutdown manages a secure and save shutdown of your http server application:
- tracks all connections
- stops the server from accepting new connections on shutdown
- graceful communication to all connected clients of server intention to shut down
- immediately destroys all sockets without an attached HTTP request
- properly handles all HTTP and HTTPS connections
- possibility to define cleanup functions (e.g. closing DB connections)
- preShutdown function if you need to have all HTTP sockets available and untouched
- choose between shutting down by function call or triggered by SIGINT, SIGTERM, ...
- choose between final forceful process termination node.js (process.exit) or clearing event loop (options).
Quick Start
Installation
$ npm install http-graceful-shutdownBasic Usage
const gracefulShutdown = require('http-graceful-shutdown');
...
// app: can be http, https, express, koa, fastity, ...
server = app.listen(...);
...
// this enables the graceful shutdown
gracefulShutdown(server);Explanation
Functionality
PARENT Process (e.g. nodemon, shell, kubernetes, ...)
โโโโโโโโโโโโโโโโโโโโโโโโโโฌโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ
โ Signal (SIGINT, SIGTERM, ...)
โ
โ
(1) (2) v NODE SERVER (HTTP, Express, koa, fastity, ...)
โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ
โ โ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ โ <โ shutdown procedure
โ โ shutdown initiated โ โ โ
โ โ โ โ โ
โ โ โ โ (8) shutdown function (9) finally fn โ
โ โ โโโโโโโโโโโโ โโโ โ โ โโ โโโโโโโโโโโโโโโโโโโโโโโโ โโโโโโโโโโโโโโ โ
โ โ (3) (4) close โ โ (7) destroy โ
โ preShutdown idle sockets โ remaining sockets โ
โ โ โ (10)
serve โ serving req. (open connection) โ (5) โ SERVER terminated
โโโโ โโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโค ^ blocked
^ โ ^ last request before โ โ
โ โ โ receiving shutdown signal โ โ
โ โ โ โ โ
โ โ โ โ โ
โ โ โ โ โ
โ โ โ Long request โ โ
Request โ V Resp โ V Resp. โ
โ โ โ CLIENT
โโโโโโโโโดโโโโโโโโโโดโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโดโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโโ
- usually, your NODE http server (the black bar in the middle) replies to client requests and sends responses
- if your server receives a termination signal (e.g. SIGINT - Ctrl-C) from its parent, http-graceful-shutdown starts the shutdown procedure
- first, http-graceful-shutdown will run the "preShutdown" (async) function. Place your own function here (passed to the options object), if you need to have all HTTP sockets available and untouched.
- then all empty connections are closed and destroyed and
- http-graceful-shutdown will block any new requests
- if possible, http-graceful-shutdown communicates to the clients that the server is about to close (connection close header)
- http-graceful-shutdown now tries to wait till all sockets are finished, then destroys the all remaining sockets
- now it is time to run the "onShutdown" (async) function (if such a function is passed to the options object)
- as soon as this onShutdown function has ended, the "finally" (sync) function is executed (if passed to the options)
- now the event loop is cleared up OR process.exit() is triggered (can be defined in the options) and the server process ends.
Options
| option | default | Comments |
|---|---|---|
| timeout | 30000 | timeout till forced shutdown (in milliseconds) |
| signals | 'SIGINT SIGTERM' | define the signals, that should be handled (separated by SPACE) |
| development | false | if set to true, no graceful shutdown is proceeded to speed up dev-process |
| preShutdown | - | not time-consuming callback function. Needs to return a promise. Here, all HTTP sockets are still available and untouched |
| onShutdown | - | not time-consuming callback function. Needs to return a promise. |
| forceExit | true | force process.exit - otherwise just let event loop clear |
| finally | - | small, not time-consuming function, that will be handled at the end of the shutdown (not in dev-mode) |
Option Explanation
- timeout: You can define the maximum time that the shutdown process may take (timeout option). If after this time, connections are still open or the shutdown process is still running, then the remaining connections will be forcibly closed and the server process is terminated.
- signals Here you can define which signals can trigger the shutdown process (SIGINT, SIGTERM, SIGKILL, SIGHUP, SIGUSR2, ...)
- development If true, the shutdown process is much shorter, because it just terminates the server, ignoring open connections, shutdown function, finally function ...
- preShutdown Place your own (not time-consuming) callback function here, if you need to have all HTTP sockets available and untouched during cleanup. Needs to return a promise. (async). If you add an input parameter to your cleanup function (optional), the SIGNAL type that caused the shutdown is passed to your cleanup function. See example.
- onShutdown place your (not time-consuming) callback function, that will handle your additional cleanup things (e.g. close DB connections). Needs to return a promise. (async). If you add an input parameter to your cleanup function (optional), the SIGNAL type that caused the shutdown is passed to your cleanup function. See example.
- finally here you can place a small (not time-consuming) function, that will be handled at the end of the shutdown e.g. for logging of shutdown. (sync)
- forceExit force process.exit() at the end of the shutdown process, otherwise just let event loop clear
Advanced Options Example
You can pass an options-object to specify your specific options for the graceful shutdown
The following example uses all possible options:
const gracefulShutdown = require('http-graceful-shutdown');
...
// app: can be http, https, express, koa, fastity, ...
server = app.listen(...);
...
// your personal cleanup function
// - must return a promise
// - the input parameter is optional (only needed if you want to
// access the signal type inside this function)
// - this function here in this example takes one second to complete
function shutdownFunction(signal) {
return new Promise((resolve) => {
console.log('... called signal: ' + signal);
console.log('... in cleanup')
setTimeout(function() {
console.log('... cleanup finished');
resolve();
}, 1000)
});
}
// finally function
// -- sync function
// -- should be very short (not time consuming)
function finalFunction() {
console.log('Server gracefulls shutted down.....')
}
// this enables the graceful shutdown with advanced options
gracefulShutdown(server,
{
signals: 'SIGINT SIGTERM',
timeout: 10000, // timeout: 10 secs
development: false, // not in dev mode
forceExit: true, // triggers process.exit() at the end of shutdown process
preShutdown: preShutdownFunction, // needed operation before httpConnections are shutted down
onShutdown: shutdownFunction, // shutdown function (async) - e.g. for cleanup DB, ...
finally: finalFunction // finally function (sync) - e.g. for logging
}
);Trigger shutdown manually
You can now trigger gracefulShutdown programatically (e.g. for tests) like so:
let shutdown
beforeAll(() => {
shutdown = gracefulShutdown(...)
})
afterAll(async () => {
await shutdown()
})Do not force process.exit()
With the forceExit option, you can define how your node server process ends: when setting forceExit to false, you just let the event loop clear and then the proccess ends automatically:
const gracefulShutdown = require('http-graceful-shutdown');
...
// app: can be http, https, express, koa, fastity, ...
server = app.listen(...);
...
// enable graceful shutdown with options:
// this option lets the event loop clear to end your node server
// no explicit process.exit() will be triggered.
gracefulShutdown(server, {
forceExit: false
});If you want an explicit process.exit() at the end, set forceExit to true (which is the default).
Debug
If you want to get debug notes (debug is a dependency of this module), just set the DEBUG environment variable to enable debugging:
export DEBUG=http-graceful-shutdown
OR on Windows:
set DEBUG=http-graceful-shutdown
Examples
You can find examples how to use http-graceful-shutdown with Express, Koa, http, http2, fastify in the examples directory.
To run the examples, be sure to install debug and express, koa or fastify.
npm install debug express koa fastify
Version history
| Version | Date | Comment |
|---|---|---|
| 3.1.13 | 2023-02-11 | fix forceExit default value |
| 3.1.12 | 2022-12-04 | changed lgtm to github scanning |
| 3.1.11 | 2022-11-18 | updated examples |
| 3.1.10 | 2022-11-17 | forceExit handling adapted |
| 3.1.9 | 2022-10-24 | updated docs, code cleanup |
| 3.1.8 | 2022-07-27 | updated docs, fixed typos |
| 3.1.7 | 2022-03-18 | updated dependencies, updated docs |
| 3.1.6 | 2022-02-27 | updated dependencies |
| 3.1.5 | 2021-11-08 | updated docs |
| 3.1.4 | 2021-08-27 | updated docs |
| 3.1.3 | 2021-08-03 | fixed handle events once (thanks to Igor Basov) |
| 3.1.2 | 2021-06-15 | fixed cleanupHttp() no timeout |
| 3.1.1 | 2021-05-13 | updated docs |
| 3.1.0 | 2021-05-08 | refactoring, added preShutdown |
| 3.0.2 | 2021-04-08 | updated docs |
| 3.0.1 | 2021-02-26 | code cleanup |
| 3.0.0 | 2021-02-25 | version 3.0 release |
| 2.4.0 | 2021-02-15 | added forceExit option (defaults to true) |
| 2.3.2 | 2019-06-14 | typescript typings fix |
| 2.3.1 | 2019-05-31 | updated docs, added typescript typings |
| 2.3.0 | 2019-05-30 | added manual shutdown (for tests) see docs below |
| 2.2.3 | 2019-02-01 | updated docs, debug |
| 2.2.2 | 2018-12-28 | updated docs, keywords |
| 2.2.1 | 2018-11-20 | updated docs |
| 2.2.0 | 2018-11-19 | added (optional) signal type to shutdown function - see example |
| 2.1.3 | 2018-11-06 | updated docs |
| 2.1.2 | 2018-11-03 | updated dependencies (version bump), updated docs |
| 2.1.1 | 2018-02-28 | extended isFunction to support e.g. AsyncFunctions |
| 2.1.0 | 2018-02-11 | bug fixing onShutdown method was called before server.close |
| 2.0.6 | 2017-11-06 | updated docs, code cleanup |
| 2.0.5 | 2017-11-06 | updated dependencies, modifications gitignore, added docs |
| 2.0.4 | 2017-09-21 | updated dependencies, modifications gitignore |
| 2.0.3 | 2017-06-18 | updated dependencies |
| 2.0.2 | 2017-05-27 | fixed return value 0 |
| 2.0.1 | 2017-04-24 | modified documentation |
| 2.0.0 | 2017-04-24 | added 'onShutdown' option, renamed 'callback' option to 'finally' |
| 1.0.6 | 2016-02-03 | adding more explicit debug information and documentation |
| 1.0.5 | 2016-02-01 | better handling of closing connections |
| 1.0.4 | 2015-10-01 | small fixes |
| 1.0.3 | 2015-09-15 | updated docs |
| 1.0.1 | 2015-09-14 | updated docs, reformated code |
| 1.0.0 | 2015-09-14 | initial release |
Comments
If you have ideas, comments or questions, please do not hesitate to contact me.
Sincerely,
Sebastian Hildebrandt, +innovations
Credits
Written by Sebastian Hildebrandt sebhildebrandt
Contributors
License 
The
MITLicense (MIT)Copyright ยฉ 2015-2023 Sebastian Hildebrandt, +innovations.
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