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https://github.com/techjacker/exit-strategy
Gracefully kill your app using node's domains
https://github.com/techjacker/exit-strategy
Last synced: 15 days ago
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Gracefully kill your app using node's domains
- Host: GitHub
- URL: https://github.com/techjacker/exit-strategy
- Owner: techjacker
- License: mit
- Created: 2013-04-17T10:57:58.000Z (over 11 years ago)
- Default Branch: master
- Last Pushed: 2013-10-07T19:38:14.000Z (about 11 years ago)
- Last Synced: 2024-10-04T12:16:31.748Z (about 1 month ago)
- Language: JavaScript
- Homepage:
- Size: 176 KB
- Stars: 0
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Exit Strategy
[](http://travis-ci.org/techjacker/exit-strategy)
- Generates error event handlers to gracefully kill your app
- Optimised for use with node's domains
- Uses [visionmedia's logger](https://github.com/visionmedia/log.js) to print POSIX error codes to STDOUT that will be picked up by [logwatch](http://linux.die.net/man/8/logwatch)
## Full Example
```JavaScript
var app = require('express').express(),
domain = require('domain'),
appDomain = domain.create(),
exitStrategy = require('exit-strategy'),
exitAppDomain = exitStrategy.app.exitAppDomain,
exitServerDomain = exitStrategy.server.exitServerDomain,
exitApp = exitAppDomain(app),
server, exitServer;
// attach error handler
appDomain.on('error', exitApp);
// wrap app execution in domain to deal with uncaught exceptions
appDomain.run(function () {
// 1. create http server
server = server.listen(app.get('port'), function() {
// you need to add this!
app.set('serverListening', true);
});
// 2. replace exitApp with exitServer error handler once inited server
exitServer = exitServerDomain(app, server);
appDomain.on('error', exitServer).removeListener('error', exitApp);
// 3. kill app for serious error evts you catch and broadcast with app.emit('seriousError')
app.on('seriousError', exitServer);
process.on('SIGTERM', exitServer);
// 4. send 502s to new connections if started server shutdown process
app.use(exitStrategy.middleware.closeGracefully(app));
// define routes etc
});
```
## Logwatch Setup
- by default logwatch watches all files in /var/log and subdirs
- make sure your app logs to a file in this dir
- logwatch will email you alerts depending upon the --detail level you set it to
## API
### .app.exitServerDomain(app, httpServer) returns -> fn (err)
- app needs get/set methods (see [getter-setter module](https://github.com/techjacker/getter-setter) if you don't want to use express)
- returns error handler function (fn (err))
```JavaScript
var app = require('express').express(),
appDomain = domain.create(),
exitAppDomain = require('exit-strategy').app.exitAppDomain(app);
var server = server.listen(app.get('port'), function() {
// you need to add this!
app.set('serverListening', true);
});
appDomain.on('error', exitServerDomain(app, server));
appDomain.run(function () {
// run your app - set up routes etc...
});
```
##### what the server domain error handler does:
1. checks if the server is active
2. calls server.close()
3. sets timer to kill app if server.close() takes more than 30s
4. calls exitApp
5. calls exitProcess
### .app.exitAppDomain(app) returns -> fn (err)
- app needs get/set methods (see getter-setter module if you don't want to use express)
- returns error handler function (fn (err))
```JavaScript
var app = require('express').express(),
appDomain = domain.create(),
exitAppDomain = require('exit-strategy').app.exitAppDomain(app);
appDomain.on('error', exitApp);
appDomain.run(function () {
// run your app
});
```
##### what the app domain error handler does:
1. if app.get('serverListening') then lets serverDomain handle it
2. sets app flag
```JavaScript
app.set('killingApp', true);
```
3. calls exitProcess
### .exitProcess(app, err)
##### what it does:
1. logs error to STDOUT
2. exits process
### .middleware.closeGracefully(app)
- Middleware to prevent new connections once the exit routine has been initiated.
- If you are load balancing then see [this guide](http://blog.argteam.com/coding/hardening-node-js-for-production-part-3-zero-downtime-deployments-with-nginx/) for configuring nginx to fail over to the next upstream server
```JavaScript
var app = require('express').express(),
// send 502s to new connections if started server shutdown process
app.use(exitStrategy.middleware.closeGracefully(app));
```