nodejs pm2 packaging and deployment

With the popularity of Node.js on the server side, more and more companies and developers are beginning to use Node.js to build their own applications. When deploying a Node.js application to a production environment, ensuring its high availability, flexibility, and scalability are very important issues. In this article, we'll cover how to use PM2 to package and deploy a Node.js application to ensure its stability in a production environment.

1. What is PM2

PM2 is an open source Node.js process management tool that can be used to manage the development, packaging and deployment of Node.js applications. It can monitor your programs and automatically restart them. It can also support functions such as load balancing and 0-second downtime upgrades, making your applications more stable and reliable in the production environment. At the same time, PM2 also integrates many commonly used Node.js tools and plug-ins, allowing developers to develop applications more efficiently.

2. Installation and configuration of PM2

Before using PM2, we need to install it first. We can use npm to install:

npm install pm2 -g

After the installation is complete, we can use the pm2 command to start and manage the application. We can use the following command to view the version and status of PM2:

$ pm2 -v
2.10.4
$ pm2 status

In PM2, we need to use configuration files to manage our applications. The configuration file is a JSON-formatted file that describes various properties of the application. A simplest configuration file looks like this:

{
  "name": "my-application",
  "script": "app.js",
  "watch": true
}

This configuration file defines an application named my-application. Its startup script is app.js and automatically restarts the application when the file is modified.

3. Basic use of PM2

Before using PM2 for development and deployment, we need to understand some basic commands:

1. Start the application

You can use the following command to start the application:

pm2 start <app.js>

where app.js is the path to the application startup script. If we have defined a startup script in the application's configuration file, we can use the following command to start the application:

pm2 start <config.json>

2. Stop the application

You can use the following command to stop Application:

pm2 stop <app_name>

Where app_name is the name of our application.

3. Restart the application

You can use the following command to restart the application:

pm2 restart <app_name>

Where app_name is the name of our application.

4. View application list

You can use the following command to view the current application list in PM2:

pm2 list

5. View application running status

You can use the following command to view the running status of applications in PM2:

pm2 status

4. Advanced use of PM2

In addition to basic use, PM2 also provides some advanced functions , allowing us to better manage Node.js applications:

1. Log management

When the application is running, PM2 will automatically generate log files. We can use the following command to view the log:

pm2 logs <app_name>

where app_name is the name of the application.

We can also use the pm2 logrotate command to manage log files to avoid excessive logs taking up space.

2. Environment variables

When developing Node.js, environment variables are a very common way to set them. PM2 also provides a way to set environment variables, allowing us to manage application configurations more flexibly.

We can set environment variables in the application's configuration file:

{
  "name": "my-application",
  "script": "app.js",
  "watch": true,
  "env": {
    "NODE_ENV": "production"
  }
}

In the above configuration file, we set an environment variable named NODE_ENV, whose value is production. In the application, we can get the value of this variable through process.env.NODE_ENV.

3. Cluster mode

Using PM2, you can also start multiple instances to achieve load balancing and high availability. We can start multiple instances through the following command:

pm2 start <config.json> -i 

where number_of_instances is the number of instances we need to start.

PM2 also supports standard load balancing and 0-second downtime upgrade, which allows us to manage multiple instances more conveniently.

5. Conclusion

In this article, we introduced the function and installation method of PM2 tool, and introduced the basic use and advanced features of PM2. By using PM2, we can better manage Node.js applications and make them more efficient and stable in production environments.

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