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https://github.com/omrilotan/graceful-shutdown
💀 Shut down server gracefully
https://github.com/omrilotan/graceful-shutdown
express expressjs graceful-shutdown nodejs server
Last synced: 28 days ago
JSON representation
💀 Shut down server gracefully
- Host: GitHub
- URL: https://github.com/omrilotan/graceful-shutdown
- Owner: omrilotan
- Created: 2019-08-22T09:13:51.000Z (about 5 years ago)
- Default Branch: master
- Last Pushed: 2021-09-24T12:57:52.000Z (about 3 years ago)
- Last Synced: 2024-09-27T18:42:13.815Z (about 1 month ago)
- Topics: express, expressjs, graceful-shutdown, nodejs, server
- Language: JavaScript
- Size: 25.4 KB
- Stars: 3
- Watchers: 3
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
Awesome Lists containing this project
README
# @routes/graceful-shutdown 
[](https://github.com/omrilotan/graceful-shutdown)
## 💀 Shut down server gracefully
[](https://github.com/omrilotan/graceful-shutdown/actions) [](https://snyk.io/test/github/omrilotan/graceful-shutdown) [](https://codeclimate.com/github/omrilotan/graceful-shutdown/maintainability)
[net.Server](https://nodejs.org/api/net.html#net_class_net_server) or [Express](https://expressjs.com/en/api.html#app.listen), whatever you're using should be fine
```js
const graceful = require('@routes/graceful-shutdown');
const server = app.listen(1337); // express will return the server instance here
graceful(server);
```
### Arguments
- First argument is an net.Server instance (including Express server)
- Second argument is options:
| option | type | meaning | default
| - | - | - | -
| `timeout` | Number | Time (in milliseconds) to wait before forcefully shutting down | `10000` (10 sec)
| `logger` | Object | Object with `info` and `error` functions (supports async loggers). Pass `false` to disable | `console`
| `events` | Array | Process events to handle | `['SIGTERM', 'SIGINT']`
| `onsuccess` | Function | Final functionality when shutdown finished correctly | `process.exit(0)`
| `onfail` | Function | Final functionality when shutdown finished incorrectly | `process.exit(1)`
Example of using options
```js
graceful(server, {
timeout: 3e4,
logger: winston.createLogger({level: 'error'}),
});
```
## What happens on process termination?
1. Process termination is interrupted
2. Open connections are instructed to end (FIN packet) and receive a new timeout to allow them to close in time
3. The server is firing a close function
4. After correct closing: `onsuccess` (default: process exists with exit code 0)
- _End correct behaviour_
5. After `timeout` passes - an error log is printed with the amount of connection that will be forcefully terminated
6. `onfail`: (default: process exists with an exit code 1)
## Add custom functionality to shutdown
Add behaviour to the graceful shut down process using a built in pub/sub mechanism
```js
const { sub, BEFORE, AFTER } = graceful(server, {...});
// Will be triggered first thing before the procedure starts
sub(BEFORE, async() => {
await flushThrottledThings();
await closeDatabaseConnections();
});
// Will be triggered once the procedure has ended
sub(AFTER, () => logger.info('Okay okay, closing down'));
```
## `server.shuttingDown`
After shutdown has initiated, the attribute `shuttingDown` is attached to server with value of `true`.
User can query this value on service to know not to send any more requests to the service
```js
app.get(
'/health',
(request, response) => response.status(server.shuttingDown ? 503 : 200).end()
);
```
## What else does graceful expose?
Monitor size of connections set. Should be similar open server connections
- `{Set} sockets` A reference to the sockets collection
```js
const { sockets } = graceful(server, {...});
// Monitor size of open connections every two minutes
setInterval(() => {
stats.gauge('graceful_stored_sockets', sockets.size);
server.getConnections((error, connections) => {
if (error) {
throw error;
} else {
stats.gauge('server_open_connections', connections);
}
});
}, 12e4);
```