PM2 Restart and Reload with the –update-env Option

In the world of software development, managing background processes is crucial for keeping applications running smoothly. PM2 is a popular tool for managing Node.js applications. This article explains how to use the –update-env option in PM2 for restarting and reloading processes.

Understanding PM2

PM2 is a tool for managing JavaScript applications, mainly for Node.js. It helps keep applications online, manage log files, and balance the load on your apps.

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The Need for --update-env

When updating your Node.js application or changing its environment settings, you need to restart or reload the processes. The --update-env option ensures that the updated environment variables are used. Without this, your application might not work as expected with old settings.

Restarting vs Reloading

Restarting and reloading processes are different in PM2:

• Restarting: Stops and starts the process again. This causes some downtime.
• Reloading: A zero-downtime approach. PM2 starts new instances and then stops the old ones.

Using --update-env with Restart

To restart a process with the --update-env option, use this command:

pm2 restart <process_name_or_id> --update-env 

Replace with your process name or ID. This command ensures your application restarts with the new environment settings.

Using --update-env with Reload

To reload a process, use this command:

pm2 reload <process_name_or_id> --update-env 

Replace with your process identifier. This is useful in production to keep the service running without downtime.

View Environment Variables of a Process

To check active environment variables, use this command:

pm2 env <process_name_or_id> 

Replace with your process identifier.

Wrapping Up

Efficient process management is key to maintaining reliable applications. By mastering PM2 and using the --update-env option, you can keep your applications up-to-date and responsive.