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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.
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
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 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.
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 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.
pm2 is a process manager for Node apps with a built-in load balancer.
pm2 is perfect when you need to spread your stateless Node.js code accross all CPUs available on a server, to keep all processes alive forever and to 0s reload them.
--watch
Tested with Node v0.11, v0.10 (https://travis-ci.org/Unitech/pm2).
The recommended Node.js version is v0.11.10
Compatible with CoffeeScript. Works on Linux & MacOS.
We're going to release a very nice product, a dashboard to monitor every part of your Node.js applications. Here are some links:
Thanks in advance and we hope that you like pm2!
The prefered Node version to run PM2, is the 0.11.10
The latest stable version can always be installed via NPM:
$ npm install pm2@latest -g
If the above fails:
$ npm install git://github.com/Unitech/pm2#master -g
Common problems on installation:
--unsafe-perm
to the npm commandsudo apt-get install build-essential
on UbuntuHello world:
$ pm2 start app.js
## Examples
Raw examples:
$ pm2 start app.js --name my-api # Name process
$ pm2 start app.js -i max # Will start maximum processes with LB depending on available CPUs
# Listing
$ pm2 list # Display all processes status
$ pm2 jlist # Print process list in raw JSON
$ pm2 prettylist # Print process list in beautified JSON
$ pm2 describe 0 # Display all informations about a specific process
$ pm2 monit # Monitor all processes
# Logs
$ pm2 logs # Display all processes logs in streaming
$ pm2 flush # Empty all log file
$ pm2 reloadLogs # Reload all logs
# Actions
$ pm2 stop all # Stop all processes
$ pm2 restart all # Restart all processes
$ pm2 reload all # Will 0s downtime reload (for NETWORKED apps)
$ pm2 gracefulReload all # Send exit message then reload (for networked apps)
$ pm2 stop 0 # Stop specific process id
$ pm2 restart 0 # Restart specific process id
$ pm2 delete 0 # Will remove process from pm2 list
$ pm2 delete all # Will remove all processes from pm2 list
# Misc
$ pm2 ping # Ensure pm2 dameon has been launched
$ pm2 start app.js -i max # Will start maximum processes depending on available CPUs
$ pm2 start app.js -i 3 # Will start 3 processes
$ pm2 start app.js --node-args="--debug=7001 --trace-deprecation" # --node-args command line option to pass options to node
$ pm2 start app.js -x # Start app.js in fork mode instead of cluster
$ pm2 start app.js -x -- -a 23 # Start app.js in fork mode and pass arguments (-a 23)
$ pm2 start app.js --name serverone # Start a process an name it as server one
# you can now stop the process by doing
# pm2 stop serverone
$ pm2 start app.json # Start processes with options declared in app.json
# Go to chapter Multi process JSON declaration for more
$ pm2 start app.js -i max -- -a 23 # Pass arguments after -- to app.js
$ pm2 start app.js -i max -e err.log -o out.log # Will start and generate a configuration file
$ pm2 --run-as-user foo start app.js # Start app.js as user foo instead of root (pm2 must be running as root)
$ pm2 --run-as-user foo --run-as-group bar start app.js # Start app.js as foo:bar instead of root:root (pm2 must be running as root)
For scripts in other languages:
$ pm2 start echo.coffee
$ pm2 start echo.php
$ pm2 start echo.py
$ pm2 start echo.sh
$ pm2 start echo.rb
$ pm2 start echo.pl
## Options
Options:
-h, --help output usage information
-V, --version output the version number
-v --verbose verbose level
-s --silent hide all messages
-m --mini-list display a compacted list without formatting
-f --force force actions
-n --name <name> set a <name> for script
-i --instances <number> launch [number] (load balanced) instances (for networked app)
-o --output <path> specify out log file
-e --error <path> specify error log file
-p --pid <pid> specify pid file
-x --execute-command execute a program using fork system
-u --user <username> define user when generating startup script
-c --cron <cron_pattern> restart a running process based on a cron pattern
-w --write write configuration in local folder
--interpreter <interpreter> the interpreter pm2 should use for executing app (bash, python...)
--no-daemon run pm2 daemon in the foreground if it doesn't exist already
--merge-logs merge logs
--watch watch application folder for changes
--node-args <node_args> space-delimited arguments to pass to node in cluster mode - e.g. --node-args="--debug=7001 --trace-deprecation"
--run-as-user <run_as_user> The user or uid to run a managed process as
--run-as-group <run_as_group> The group or gid to run a managed process as
PM2 is a process manager, as said, pm2 can start, stop, restart and delete processes.
Start a process:
$ pm2 start app.js --name "my-api"
$ pm2 start web.js --name "web-interface"
Now let's say I need to stop the web-interface:
$ pm2 stop web-interface
As you can see the process hasn't disapeared. It is still there but now in stopped
status.
To restart it just do:
$ pm2 restart web-interface
Now I want to delete the app from the pm2 process list. To do that:
$ pm2 delete web-interface
## Process listing
To list all running processes:
$ pm2 list
# Or
$ pm2 [list|ls|l|status]
To get more details about a specific process:
$ pm2 describe 0
## Monitoring CPU/Memory usage
Monitor all processes launched:
$ pm2 monit
## Logs management
Displaying logs of specified process or all processes in realtime:
$ pm2 logs
$ pm2 logs big-api
$ pm2 flush # Clear all the logs
To reload all logs, you can send SIGUSR2
to the pm2 process.
You can also reload all logs via the command line with:
$ pm2 reloadLogs
--merge-logs : merge logs from different instances but keep error and out separated
## Clustering
Launch max
instances (max
depending on the number of CPUs available) and set the load balancer to balance queries among process:
$ pm2 start app.js --name "API" -i max
If your app is well-designed (stateless) you'll be able to process many more queries.
Important concepts to make a Node.js app stateless:
As opposed to restart
, which kills and restarts the process, reload
achieves a 0-second-downtime reload.
Warning This feature only works for apps in cluster mode (the default mode), that uses HTTP/HTTPS/Socket connections.
To reload an app:
$ pm2 reload api
If the reload system hasn't managed to reload gracefully, a timeout will simply kill the process and will restart it.
Sometimes you can experience a very long reload, or a reload that doesn't work (fallback to restart).
It means that your app still has open connections on exit.
To work around this problem you have to use the graceful reload.
Graceful reload is a mechanism that will send a shutdown message to your process before reloading it.
You can control the time that the app has to shutdown via the PM2_GRACEFUL_TIMEOUT
environment variable.
Example:
process.on('message', function(msg) {
if (msg == 'shutdown') {
// Your process is going to be reloaded
// You have to close all database/socket.io/* connections
console.log('Closing all connections...');
// You will have 4000ms to close all connections before
// the reload mechanism will try to do its job
setTimeout(function() {
console.log('Finished closing connections');
// This timeout means that all connections have been closed
// Now we can exit to let the reload mechanism do its job
process.exit(0);
}, 1500);
}
});
Then use the command:
$ pm2 gracefulReload [all|name]
## Startup script
PM2 has the amazing ability to generate startup scripts and configure it. PM2 is also smart enough to save all your process list and to bring back all your processes on restart.
$ pm2 startup [ubuntu|centos|systemd]
Warning It's tricky to make this feature work generically, so once PM2 has setup your startup script, reboot your server to make sure that PM2 has launched your apps!
Two types of startup scripts are available:
ubuntu
or centos
)systemd
option)The startup options are using:
updaterc.d
and the script lib/scripts/pm2-init.sh
chkconfig
and the script lib/scripts/pm2-init-centos.sh
systemctl
and the script lib/scripts/pm2.service
Let's say you want the startup script to be executed under another user.
Just use the -u <username>
option !
$ pm2 startup ubuntu -u www
Dump all processes status and environment managed by pm2:
$ pm2 dump
It populates the file ~/.pm2/dump.pm2
by default.
To bring back the latest dump:
$ pm2 resurrect
## Watch & Restart
pm2 can automatically restart your app when a file changes in the current directory or its subdirectories:
$ pm2 start app.js --watch
## JSON app declaration
You can define parameters for your apps in processes.json
:
[{
"name" : "echo",
"script" : "./examples/args.js",
"args" : "['--toto=heya coco', '-d', '1']",
"env": {
"NODE_ENV": "production",
"AWESOME_SERVICE_API_TOKEN": "xxx"
}
}, {
"name" : "api",
"script" : "./examples/child.js",
"instances" : "4",
"error_file" : "./examples/child-err.log",
"out_file" : "./examples/child-out.log",
"pid_file" : "./examples/child.pid",
"exec_mode" : "cluster_mode",
"port" : 9005
}, {
"name" : "auto-kill",
"script" : "./examples/killfast.js",
"min_uptime" : "100",
"exec_mode" : "fork_mode",
}]
Then run:
$ pm2 start processes.json
$ pm2 stop processes.json
$ pm2 delete processes.json
$ pm2 restart processes.json
Launching PM2 without daemonizing itself:
$ pm2 start app.js --no-daemon
Sending a system signal to a process:
$ pm2 sendSignal SIGUSR2 my-app
## Configuration file
You can specifiy the following options by editing the file ~/.pm2/custom_options.sh
:
PM2_RPC_PORT
PM2_PUB_PORT
PM2_BIND_ADDR
PM2_API_PORT
PM2_GRACEFUL_TIMEOUT
PM2_MODIFY_REQUIRE
PM2_NODE_OPTIONS
$ pm2 web
## Enabling Harmony ES6
You can enable Harmony ES6 by setting PM2_NODE_OPTIONS='--harmony'
environment variable option when you start pm2 (pm2 should not be already daemonized).
To pass this option by default, you can edit ~/.pm2/custom_options.sh
and add:
export PM2_NODE_OPTIONS='--harmony'
Then:
$ pm2 dump
$ pm2 exit
$ pm2 resurrect
If ES6 has been enabled you should see this message at the beggining of each pm2 command:
● ES6 mode
$ pm2 start my_app.js --node-args="--harmony"
## CoffeeScript
$ pm2 start my_app.coffee
That's all!
We recommend (and you must) write stateless NodeJS apps. Apps that don't retain any form of local variables or local instances or whatever local. Every data, states, websocket session, session data, must be shared via any kind of database.
We recommend using Redis for sharing session data, websocket.
We recommend following the 12 factor convention : http://12factor.net/
## Setup PM2 on a serverHow To Use PM2 to Setup a Node.js Production Environment On An Ubuntu VPS
## Log and PID filesBy default, logs (error and output), pid files, dumps, and pm2 logs are located in ~/.pm2/
:
.pm2/
├── dump.pm2
├── custom_options.sh
├── pm2.log
├── pm2.pid
├── logs
└── pids
## Execute any script: What is fork mode?
The default mode of PM2 consists of wrapping the code of your node application into the Node Cluster module. It's called the cluster mode.
There is also a more classical way to execute your app, like node-forever does, called the fork mode.
In fork mode almost all options are the same as the cluster mode. But there is no reload
or gracefulReload
command.
By using the fork mode you will lose core features of PM2 like the automatic clusterization of your code over all CPUs available and the 0s reload.
So use it if you only need a forever-like behaviour.
Here is how to start your app within a fork:
$ pm2 start app.js -x # Will start your app.js in fork mode
$ pm2 list # You will see that on the row "mode" it's written "fork"
You can also exec scripts written in other languages:
$ pm2 start my-bash-script.sh -x --interpreter bash
$ pm2 start my-python-script.py -x --interpreter python
## JSON app configuration via pipe from stdout
Pull-requests:
#!/bin/bash
read -d '' my_json <<_EOF_
[{
"name" : "app1",
"script" : "/home/projects/pm2_nodetest/app.js",
"instances" : "4",
"error_file" : "./logz/child-err.log",
"out_file" : "./logz/child-out.log",
"pid_file" : "./logz/child.pid",
"exec_mode" : "cluster_mode",
"port" : 4200
}]
_EOF_
echo $my_json | pm2 start -
## Is my production server ready for PM2?
Just try the tests before using PM2 on your production server
$ git clone https://github.com/Unitech/pm2.git
$ cd pm2
$ npm install # Or do NODE_ENV=development npm install if some packages are missing
$ npm test
If a test is broken please report us issues here Also make sure you have all dependencies needed. For Ubuntu:
$ sudo apt-get install build-essential
# nvm is a Node.js version manager - https://github.com/creationix/nvm
$ wget -qO- https://raw.github.com/creationix/nvm/master/install.sh | sh
$ nvm install v0.11.10
$ nvm use v0.11.10
$ nvm alias default v0.11.10
## Contributing/Development mode
To hack PM2, it's pretty simple:
$ pm2 kill # kill the current pm2
$ git clone my_pm2_fork.git
$ cd pm2/
$ DEBUG=* PM2_DEBUG=true ./bin/pm2 --no-daemon
Each time you edit the code, be sure to kill and restart pm2 to make changes taking effect.
$ npm install git://github.com/Unitech/pm2#development -g
## Known bugs and workarounds
First, install the lastest pm2 version:
$ npm install -g pm2@latest
So if you feel that this problem is important for your use case, use the fork mode instead. By using the fork mode you will lose core features of PM2 like the automatic clusterization of your code over all CPUs available and the 0s reload.
$ pm2 start index.js -x # start my app in fork mode
For more information about this, see issue #74.
Cannot read property 'getsockname' of undefined
When using the cluster mode (by default) you can't use ports from 0 to 1024. If you really need to exec in this range use the fork mode with the -x
parameter.
By using the fork mode you will lose core features of PM2 like the automatic clusterization of your code over all CPUs available and the 0s reload.
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Thanks to Devo.ps and Wiredcraft for their knowledge and expertise.
# LicenseFiles in lib/
are made available under the terms of the GNU Affero General Public License (AGPL).
pm2-interface
is made under the terms of the Apache V2 license.
0.8.2
FAQs
Production process manager for Node.JS applications with a built-in load balancer.
The npm package pm2 receives a total of 2,118,811 weekly downloads. As such, pm2 popularity was classified as popular.
We found that pm2 demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 1 open source maintainer collaborating on the project.
Did you know?
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