PM2 is a Production Runtime and Process Manager for Node.js applications with a built-in Load Balancer.
It allows you to keep applications alive forever, to reload them without downtime and facilitate common Devops tasks.
Starting an application in production mode is as easy as:
```bash
$ pm2 start app.js
```
PM2 is constantly assailed by [more than 1800 tests](https://travis-ci.org/Unitech/pm2).
Official website: [http://pm2.keymetrics.io/](http://pm2.keymetrics.io/)
Works on Linux (stable) & macOS (stable) & Windows (stable).
All Node.js versions are supported starting Node.js 0.12.
[](https://nodei.co/npm/pm2/)
### Installing PM2
```bash
$ npm install pm2 -g
```
*npm is a builtin CLI when you install Node.js - [Installing Node.js with NVM](https://keymetrics.io/2015/02/03/installing-node-js-and-io-js-with-nvm/)*
### Start an application
You can start any application (Node.js, Python, Ruby, binaries in $PATH...) like that:
```bash
$ pm2 start app.js
```
Your app is now daemonized, monitored and kept alive forever.
[More about Process Management](http://pm2.keymetrics.io/docs/usage/process-management/)
### Container Support
With the drop-in replacement command for `node`, called `pm2-runtime`, run your Node.js application in a proper production environment.
There is also an [officialy supported Docker image](https://hub.docker.com/r/keymetrics/pm2/).
Using it is seamless:
```
FROM keymetrics/pm2:latest-alpine
[...]
CMD [ "pm2-runtime", "npm", "--", "start" ]
```
[Read More about the dedicated integration](http://pm2.keymetrics.io/docs/usage/docker-pm2-nodejs/)
### Managing a Process
Once applications are started you can manage them easily:
To list all running processes:
```bash
$ pm2 list
```
Managing processes is straightforward:
```bash
$ pm2 stop
$ pm2 restart
$ pm2 delete
```
To have more details on a specific process:
```bash
$ pm2 describe
```
To monitor logs, custom metrics, process information:
```bash
$ pm2 monit
```
[More about Process Management](http://pm2.keymetrics.io/docs/usage/process-management/)
### Cluster Mode: Node.js Load Balancing & Hot Reload
The Cluster mode is a special mode when starting a Node.js application, it starts multiple processes and load-balance HTTP/TCP/UDP queries between them. This increase overall performance (by a factor of x10 on 16 cores machines) and reliability (faster socket re-balancing in case of unhandled errors).
Starting a Node.js application in cluster mode that will leverage all CPUs available:
```bash
$ pm2 start api.js -i
```
`` can be `'max'`, `-1` (all cpu minus 1) or a specified number of instances to start.
**Hot Reload**
Hot Reload allows to update an application without any downtime:
```bash
$ pm2 reload all
```
Seamlessly supported by all major Node.js frameworks and any Node.js applications without any code change:
[More informations about how PM2 make clustering easy](https://keymetrics.io/2015/03/26/pm2-clustering-made-easy/)
### Terminal Based Monitoring
Monitor all processes launched straight from the command line:
```bash
$ pm2 monit
```
### Monitor PM2 and Applications with our SaaS
Once you deploy your application in production, you can monitor, debug and profile it externally with our [SaaS Monitoring](https://keymetrics.io).
To start monitoring applications from the terminal:
```bash
$ pm2 register
```
[More about PM2 Monitoring](http://docs.keymetrics.io/)
### Expose Custom Metrics
To get more insights on how your application behave, plug custom metrics inside your code and monitor them with the `pm2 monit` command:
In your project install [pmx](https://github.com/keymetrics/pmx):
```bash
$ npm install pmx --save
```
Then plug a custom metric:
```javascript
var Probe = require('pmx').probe();
var counter = 1;
var metric = Probe.metric({
name : 'Counter',
value : function() {
return counter;
}
});
setInterval(function() {
counter++;
}, 1000);
```
Then to see the metric type from in the terminal:
```bash
$ pm2 monitor
```
Metric, Counter, Histogram and Meters are [available](http://pm2.keymetrics.io/docs/usage/process-metrics/)
### Log facilities
Displaying logs of a specified process or all processes, in real time is easy:
```bash
$ pm2 logs ['all'|app_name|app_id] [--json] [--format] [--raw]
```
Standard, Raw, JSON and formated output are available.
Examples:
```bash
$ pm2 logs APP-NAME # Display APP-NAME logs
$ pm2 logs --json # JSON output
$ pm2 logs --format # Formated output
$ pm2 flush # Flush all logs
$ pm2 reloadLogs # Reload all logs
```
[More about log management](http://pm2.keymetrics.io/docs/usage/log-management/)
### Startup script generation
PM2 can generates and configure a startup script to keep PM2 and your processes alive at every server restart.
Supports init systems like: **systemd** (Ubuntu 16, CentOS, Arch), **upstart** (Ubuntu 14/12), **launchd** (MacOSx, Darwin), **rc.d** (FreeBSD).
```bash
# Auto detect init system + generate and setup PM2 boot at server startup
$ pm2 startup
# Manually specify the startup system
# Can be: systemd, upstart, launchd, rcd
$ pm2 startup [platform]
# Disable and remove PM2 boot at server startup
$ pm2 unstartup
```
To save/freeze a process list on reboot:
```bash
$ pm2 save
```
[More about startup scripts](http://pm2.keymetrics.io/docs/usage/startup/)
### Commands Cheatsheet
```bash
# General
$ npm install pm2 -g # Install PM2
$ pm2 start app.js # Start, Daemonize and auto-restart application (Node)
$ pm2 start app.py # Start, Daemonize and auto-restart application (Python)
$ pm2 start npm -- start # Start, Daemonize and auto-restart Node application
# Cluster Mode (Node.js only)
$ pm2 start app.js -i 4 # Start 4 instances of application in cluster mode
# it will load balance network queries to each app
$ pm2 reload all # Zero Second Downtime Reload
$ pm2 scale [app-name] 10 # Scale Cluster app to 10 process
# Process Monitoring
$ pm2 list # List all processes started with PM2
$ pm2 list --sort= # Sort all processes started with PM2
$ pm2 monit # Display memory and cpu usage of each app
$ pm2 show [app-name] # Show all information about application
# Log management
$ pm2 logs # Display logs of all apps
$ pm2 logs [app-name] # Display logs for a specific app
$ pm2 logs --json # Logs in JSON format
$ pm2 flush
$ pm2 reloadLogs
# Process State Management
$ pm2 start app.js --name="api" # Start application and name it "api"
$ pm2 start app.js -- -a 34 # Start app and pass option "-a 34" as argument
$ pm2 start app.js --watch # Restart application on file change
$ pm2 start script.sh # Start bash script
$ pm2 start app.json # Start all applications declared in app.json
$ pm2 reset [app-name] # Reset all counters
$ pm2 stop all # Stop all apps
$ pm2 stop 0 # Stop process with id 0
$ pm2 restart all # Restart all apps
$ pm2 delete all # Kill and delete all apps
$ pm2 delete 0 # Delete app with id 0
# Startup/Boot management
$ pm2 startup # Detect init system, generate and configure pm2 boot on startup
$ pm2 save # Save current process list
$ pm2 resurrect # Restore previously saved processes
$ pm2 unstartup # Disable and remove startup system
$ pm2 update # Save processes, kill PM2 and restore processes
$ pm2 init # Generate a sample js configuration file
# Deployment
$ pm2 deploy app.json prod setup # Setup "prod" remote server
$ pm2 deploy app.json prod # Update "prod" remote server
$ pm2 deploy app.json prod revert 2 # Revert "prod" remote server by 2
# Module system
$ pm2 module:generate [name] # Generate sample module with name [name]
$ pm2 install pm2-logrotate # Install module (here a log rotation system)
$ pm2 uninstall pm2-logrotate # Uninstall module
$ pm2 publish # Increment version, git push and npm publish
```
Also check out the [example folder](https://github.com/Unitech/pm2/tree/master/examples) to discover all features.
## Updating PM2
```bash
# Install latest PM2 version
$ npm install pm2@latest -g
# Save process list, exit old PM2 & restore all processes
$ pm2 update
```
*PM2 updates are seamless*
## Module system
PM2 embeds a simple and powerful module system. Installing a module is straightforward:
```bash
$ pm2 install
```
Here are some PM2 compatible modules (standalone Node.js applications managed by PM2):
[**pm2-logrotate**](https://github.com/pm2-hive/pm2-logrotate) auto rotate logs of PM2 and applications managed
[**pm2-webshell**](https://github.com/pm2-hive/pm2-webshell) expose a fully capable terminal in browsers
[**pm2-server-monit**](https://github.com/pm2-hive/pm2-server-monit) monitor your server health
[Writing your own module](http://pm2.keymetrics.io/docs/advanced/pm2-module-system/)
## Keymetrics monitoring
[](https://app.keymetrics.io/#/register)
If you manage your NodeJS app with PM2, Keymetrics makes it easy to monitor and manage apps across servers.
Feel free to try it:
[Discover the monitoring dashboard for PM2](https://app.keymetrics.io/#/register)
Thanks in advance and we hope that you like PM2!
## More about PM2
- [Application Declaration via JS files](http://pm2.keymetrics.io/docs/usage/application-declaration/)
- [Watch & Restart](http://pm2.keymetrics.io/docs/usage/watch-and-restart/)
- [PM2 API](http://pm2.keymetrics.io/docs/usage/pm2-api/)
- [Deployment workflow](http://pm2.keymetrics.io/docs/usage/deployment/)
- [PM2 on Heroku/Azure/App Engine](http://pm2.keymetrics.io/docs/usage/use-pm2-with-cloud-providers/)
- [PM2 auto completion](http://pm2.keymetrics.io/docs/usage/auto-completion/)
- [Using PM2 in ElasticBeanStalk](http://pm2.keymetrics.io/docs/tutorials/use-pm2-with-aws-elastic-beanstalk/)
- [PM2 Tutorial Series](https://futurestud.io/tutorials/pm2-utility-overview-installation)
## CHANGELOG
[CHANGELOG](https://github.com/Unitech/PM2/blob/master/CHANGELOG.md)
## Contributors
[Contributors](http://pm2.keymetrics.io/hall-of-fame/)
## License
PM2 is made available under the terms of the GNU Affero General Public License 3.0 (AGPL 3.0).
We can deliver other licenses, for more informations [contact sales](mailto:sales@keymetrics.io).
[](https://github.com/igrigorik/ga-beacon)
