pm2

What is pm2?

PM2 is a production 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 to facilitate common system admin tasks.

What are pm2's main functionalities?

Process Management

Start an application with PM2 and keep it running in the background.

pm2 start app.js

Load Balancing

Enable load balancing by starting multiple instances of the application across all CPUs.

pm2 start app.js -i max

Monitoring

Monitor all processes launched with PM2 using a terminal-based dashboard.

pm2 monit

Logging

Display logs of all processes in real-time, or target specific processes.

pm2 logs

Startup Script

Generate a startup script to resurrect PM2 and all processes on server reboot.

pm2 startup

Update Processes

Reload all processes in the cluster without downtime.

pm2 reload all

Other packages similar to pm2

forever

Forever is a simple CLI tool for ensuring that a given script runs continuously (i.e., forever). It is similar to PM2 but lacks some of its advanced features like application monitoring and load balancing.

nodemon

Nodemon is a utility that monitors for any changes in your source and automatically restarts your server. It is often used in development environments, unlike PM2 which is tailored for production use.

strong-pm

StrongLoop Process Manager (strong-pm) is a production process manager for Node.js applications with features like remote deployment and performance monitoring. It is part of the StrongLoop suite, which is now owned by IBM.

supervisor

Supervisor is a client/server system that allows its users to monitor and control a number of processes on UNIX-like operating systems. It is not specifically designed for Node.js and is more general-purpose.

README

P(rocess) M(anager) 2
Runtime Edition

PM2 is a production 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 to facilitate common system admin tasks.

Starting an application in production mode is as easy as:

$ pm2 start app.js

PM2 is constantly assailed by more than 1800 tests.

Official website: https://pm2.keymetrics.io/

Works on Linux (stable) & macOS (stable) & Windows (stable). All Node.js versions are supported starting Node.js 12.X.

Installing PM2

With NPM:

$ npm install pm2 -g

Or if you don't have Node.js installed:

wget -qO- https://getpm2.com/install.sh | bash

Start an application

You can start any application (Node.js, Python, Ruby, binaries in $PATH...) like that:

$ pm2 start app.js

Your app is now daemonized, monitored and kept alive forever.

Managing Applications

Once applications are started you can manage them easily:

To list all running applications:

$ pm2 list

Managing apps is straightforward:

$ pm2 stop     <app_name|namespace|id|'all'|json_conf>
$ pm2 restart  <app_name|namespace|id|'all'|json_conf>
$ pm2 delete   <app_name|namespace|id|'all'|json_conf>

To have more details on a specific application:

$ pm2 describe <id|app_name>

To monitor logs, custom metrics, application information:

$ pm2 monit

More about Process Management

Cluster Mode: Node.js Load Balancing & Zero Downtime 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:

$ pm2 start api.js -i <processes>

<processes> can be 'max', -1 (all cpu minus 1) or a specified number of instances to start.

Zero Downtime Reload

Hot Reload allows to update an application without any downtime:

$ 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

Container Support

With the drop-in replacement command for node, called pm2-runtime, run your Node.js application in a hardened production environment. Using it is seamless:

RUN npm install pm2 -g
CMD [ "pm2-runtime", "npm", "--", "start" ]

Read More about the dedicated integration

Terminal Based Monitoring

Monitor all processes launched straight from the command line:

$ pm2 monit

Log Management

To consult logs just type the command:

$ pm2 logs

Standard, Raw, JSON and formated output are available.

Examples:

$ 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

Startup Scripts Generation

PM2 can generates and configure a Startup Script to keep PM2 and your processes alive at every server restart.

Init Systems Supported: systemd, upstart, launchd, rc.d

# Generate Startup Script
$ pm2 startup

# Freeze your process list across server restart
$ pm2 save

# Remove Startup Script
$ pm2 unstartup

More about Startup Scripts Generation

PM2 Modules

PM2 embeds a simple and powerful module system. Installing a module is straightforward:

$ pm2 install <module_name>

Here are some PM2 compatible modules (standalone Node.js applications managed by PM2):

pm2-logrotate automatically rotate logs and limit logs size
pm2-server-monit monitor the current server with more than 20+ metrics and 8 actions

Updating PM2

# Install latest PM2 version
$ npm install pm2@latest -g
# Save process list, exit old PM2 & restore all processes
$ pm2 update

PM2 updates are seamless

PM2+ Monitoring

If you manage your apps with PM2, PM2+ makes it easy to monitor and manage apps across servers.

Feel free to try it:

Discover the monitoring dashboard for PM2

Thanks in advance and we hope that you like PM2!

CHANGELOG

CHANGELOG

Contributors

Contributors

License

PM2 is made available under the terms of the GNU Affero General Public License 3.0 (AGPL 3.0). For other licenses contact us.

Changelog

5.0.1/5.0.2

• fix npm install --no-optional pm2