# Keep a node application constantly running

# Use PM2 as a process manager

PM2 lets you run your nodejs scripts forever. In the event that your application crashes, PM2 will also restart it for you.

Install PM2 globally to manager your nodejs instances

npm install pm2 -g

Navigate to the directory in which your nodejs script resides and run the following command each time you want to start a nodejs instance to be monitored by pm2:

pm2 start server.js --name "app1"

# Useful commands for monitoring the process

  • List all nodejs instances managed by pm2 `pm2 list`
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  • Stop a particular nodejs instance `pm2 stop `
  • Delete a particular nodejs instance `pm2 delete `
  • Restart a particular nodejs instance `pm2 restart `
  • Monitoring all nodejs instances `pm2 monit`
  • enter image description here

  • Stop pm2 `pm2 kill`
  • As opposed to restart, which kills and restarts the process, reload achieves a 0-second-downtime reload `pm2 reload `
  • View logs `pm2 logs `
  • # Running and stopping a Forever daemon

    To start the process:

    $ forever start index.js
    warn:    --minUptime not set. Defaulting to: 1000ms
    warn:    --spinSleepTime not set. Your script will exit if it does not stay up for at least 1000ms
    info:    Forever processing file: index.js
    
    
    

    List running Forever instances:

    $ forever list
    info:    Forever processes running
    
    |data: | index | uid | command          | script      |forever pid|id   | logfile                |uptime        |
    |---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|----|-----|---|---|---|---|---|---|---|---|---|---------------|---|---|---|---|---|---|---|---|---|----------|---|---|---|---|---|---|---|---|---|--------|-----|---|---|---|---|---|---|---|---|---|---------------------|---|---|---|---|---|---|---|---|---|-----------|
    |data: | [0]   |f4Kt |/usr/bin/nodejs   | src/index.js|2131       | 2146|/root/.forever/f4Kt.log | 0:0:0:11.485 |
    
    
    

    Stop the first process:

    $ forever stop 0
    
    $ forever stop 2146
    
    $ forever stop --uid f4Kt
    
    $ forever stop --pidFile 2131
    
    

    # Continuous running with nohup

    An alternative to forever on Linux is nohup.

    To start a nohup instance

    1. cd to the location of app.js or wwwfolder
    2. run nohup nodejs app.js &

    To kill the process

    1. run ps -ef|grep nodejs
    2. kill -9 <the process number>

    # Process Mangement with Forever

    Installation

    npm install forever -g
    cd /node/project/directory
    
    

    Usages

    forever start app.js