title: PM2 date: 2022-11-25 18:10:00 background: bg-[#230769] tags: - process categories: - Linux Command intro: |
The latest PM2 version is installable with NPM or Yarn ``` shell script $ npm install pm2@latest -g
OR
``` shell script
$ yarn global add pm2
The simplest way to start, daemonize and monitor your application is by using this command line ``` shell script $ pm2 start app.js
Or start any other application easily
``` shell script
$ pm2 start bashscript.sh
$ pm2 start python-app.py --watch
$ pm2 start binary-file -- --port 1520
Specify an app name
``` shell script
--name
Watch and Restart app when files change
``` shell script
--watch
Set memory threshold for app reload ``` shell script --max-memory-restart <200MB>
Specify log file
``` shell script
--log <log_path>
Pass extra arguments to the script ``` shell script -- arg1 arg2 arg3
Delay between automatic restarts
``` shell script
--restart-delay <delay in ms>
Prefix logs with time ``` shell script --time
Do not auto restart app
``` shell script
--no-autorestart
Specify cron for forced restart
``` shell script
--cron
Attach to application log
``` shell script
--no-daemon
Managing application state is simple here are the commands ``` shell script \( pm2 restart app_name \) pm2 reload app_name \( pm2 stop app_name \) pm2 delete app_name
#### Instead of app_name you can pass
- `all` to act on all processes
- `id` to act on a specific process id
### Check status, logs, metrics {.row-span-2}
Now that you have started this application, you can check its status, logs, metrics and even get the online dashboard with [pm2.io](https://pm2.io/).
List the status of all application managed by PM2
``` shell script
$ pm2 [list|ls|status]
To display logs in realtime ``` shell script $ pm2 logs
To dig in older logs
``` shell script
$ pm2 logs --lines 200
Here is a realtime dashboard that fits directly into your terminal ``` shell script $ pm2 monit
Web based dashboard, cross servers with diagnostic system
``` shell script
$ pm2 plus
For Node.js applications, PM2 includes an automatic load balancer that will share all HTTP[s]/Websocket/TCP/UDP connections between each spawned processes.
To start an application in Cluster mode ``` shell script $ pm2 start app.js -i max
Read more about cluster mode [here](https://pm2.keymetrics.io/docs/usage/quick-start/).
### Ecosystem File {.row-span-2}
You can also create a configuration file, called Ecosystem File, to manage multiple applications. To generate an Ecosystem file
``` shell script
$ pm2 ecosystem
This will generate an ecosystem.config.js file
module.exports = {
apps : [{
name: "app",
script: "./app.js",
env: {
NODE_ENV: "development",
},
env_production: {
NODE_ENV: "production",
}
}, {
name: 'worker',
script: 'worker.js'
}]
}
And start it easily ``` shell script $ pm2 start ecosystem.config.js
Read more about application declaration [here](https://pm2.keymetrics.io/docs/usage/application-declaration/)
### Setup startup script
Restarting PM2 with the processes you manage on server boot/reboot is critical. To solve this, just run this command to generate an active startup script
``` shell script
$ pm2 save
Read more about startup script generator here
It’s pretty easy with the --watch option
$ cd /path/to/my/app
$ pm2 start env.js --watch --ignore-watch="node_modules"
This will watch & restart the app on any file change from the current directory + all subfolders and it will ignore any changes in the node_modules folder --ignore-watch="node_modules".
You can then use pm2 logs to check for restarted app logs.
Here are some commands that are worth knowing. Just try them with a sample application or with your current web application on your development machine
Fork mode ```shell script $ pm2 start app.js --name my-api # Name process
Cluster mode
```shell script
$ pm2 start app.js -i 0 # Will start maximum processes with LB depending on available CPUs
$ pm2 start app.js -i max # Same as above, but deprecated.
$ pm2 scale app +3 # Scales `app` up by 3 workers
$ pm2 scale app 2 # Scales `app` up or down to 2 workers total
Listing ```shell script \( pm2 list # Display all processes status \) pm2 jlist # Print process list in raw JSON $ pm2 prettylist # Print process list in beautified JSON
$ pm2 describe 0 # Display all information about a specific process
$ pm2 monit # Monitor all processes
Logs
```shell script
$ pm2 logs [--raw] # Display all processes logs in streaming
$ pm2 flush # Empty all log files
$ pm2 reloadLogs # Reload all logs
Actions ```shell script \( pm2 stop all # Stop all processes \) pm2 restart all # Restart all processes
$ pm2 reload all # Will 0s downtime 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
```shell script
$ pm2 reset <process> # Reset meta data (restarted time...)
$ pm2 updatePM2 # Update in memory pm2
$ pm2 ping # Ensure pm2 daemon has been launched
$ pm2 sendSignal SIGUSR2 my-app # Send system signal to script
$ pm2 start app.js --no-daemon
$ pm2 start app.js --no-vizion
$ pm2 start app.js --no-autorestart
We made it simple, there is no breaking change between releases and the procedure is straightforward ```shell script $ npm install pm2@latest -g
Then update the in-memory PM2
```shell script
$ pm2 update