NGINX PM2 VPS: Build a high-availability application service cluster

NGINX PM2 VPS: To build a high-availability application service cluster, specific code examples are required

Introduction:
In today's Internet era, high availability has become One of the important elements for building stable and reliable application services. In order to achieve high availability, many enterprises and developers have begun to choose to use clusters to deploy their applications. In a cluster, using NGINX and PM2 as load balancer and process management tools are very common choices. This article will introduce how to use NGINX, PM2 and VPS to build a high-availability application service cluster, and give specific code examples.

1. What is NGINX and PM2

1. NGINX is a lightweight, high-performance web server that can serve as a reverse proxy server, load balancer, HTTP cache server, etc. . Through NGINX, we can distribute requests to multiple application servers on the backend, thereby improving system reliability and performance.
2. PM2 is a process management tool for Node.js applications. It can help us easily manage the start, stop, restart and log output of Node.js applications. Through PM2, we can automatically restart the application when the application exits abnormally, thus ensuring the availability of the service.

2. Build NGINX reverse proxy and load balancing
Before building a high-availability application service cluster, we first need to build a basic NGINX reverse proxy and load balancing environment. Here is a simple NGINX configuration example:

http {
    upstream app_servers {
        server 127.0.0.1:3000;
        server 127.0.0.1:3001;
        server 127.0.0.1:3002;
    }

    server {
        listen 80;

        location / {
            proxy_pass http://app_servers;
        }
    }
}

In the above configuration, we have defined an upstream block named app_servers which lists the addresses of our application servers and port. NGINX will distribute requests to these servers according to the load balancing algorithm. By configuring the proxy_pass directive, NGINX implements the reverse proxy function and forwards client requests to the back-end application server through NGINX.

3. Use PM2 to manage the Node.js application process
After building the NGINX reverse proxy and load balancing environment, we need to use PM2 to manage the process of our Node.js application. The following is a simple PM2 configuration example:

module.exports = {
  apps : [
    {
      name      : "app",
      script    : "app.js",
      instances : "max",
      exec_mode : "cluster"
    }
  ]
}

In the above configuration, we define an application named app and specify the application’s entry file as app. js. By setting instances to max and exec_mode to cluster, we tell PM2 to create as many processes as possible when starting the application, thus achieving High concurrent processing capabilities of applications.

4. Use VPS to achieve high availability cluster
Based on the above, we can use VPS to build a high availability application service cluster to provide more stable and reliable services. The following is a simple VPS cluster example:

server {
    listen 80;

    location / {
        proxy_pass http://backend;
    }

    location /status {
        stub_status on;
        allow 127.0.0.1;
        deny all;
    }
}

upstream backend {
    server backend1.example.com;
    server backend2.example.com;
    server backend3.example.com;
}

In the above configuration, we use VPS as the front-end load balancer. When a request comes in, the VPS will forward the request to multiple application servers on the backend to achieve load balancing and high availability.

In this way, even if one of the application servers fails, other normally running servers can still keep the service running, thus improving the reliability of the system.

Conclusion:
By using NGINX, PM2 and VPS, we can build a high-availability application service cluster to achieve load balancing and fault recovery. Such an architecture can improve application availability and be able to handle more concurrent requests. Hopefully the code examples provided in this article will help you better understand and apply these tools and techniques. Let’s build stable and reliable application services together!

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