Detailed interpretation of Nginx's load balancing and high availability deployment solutions

Detailed explanation of Nginx's load balancing and high availability deployment solution

Introduction:
In today's Internet applications, high availability and load balancing are indispensable key elements. As a high-performance open source web server and reverse proxy server, Nginx is widely used to build high-availability and high-concurrency application architectures. This article will explain Nginx's load balancing and high availability deployment solutions in detail and provide corresponding code examples.

1. Overview of Load Balancing
Load balancing distributes network traffic to multiple servers to achieve balanced utilization of resources and improve the overall performance of the system. Nginx achieves load balancing through its reverse proxy function. In Nginx, you can define a group of backend servers by configuring upstream, and Nginx will distribute requests to different servers according to the set algorithm.

2. Commonly used load balancing algorithms

1. Round-robin: The default load balancing algorithm distributes requests to the back-end servers in sequence.
2. Weighted round-robin: You can configure a weight for each server to distribute requests proportionally.
3. IP Hash: Hash calculation is performed based on the client IP address, and requests for the same IP are distributed to the same server. It is suitable for applications that need to maintain sessions.
4. Least connected: Distribute requests to the server with the smallest number of current connections.
5. URL Hash: Hash calculation is performed based on the requested URL, and requests for the same URL are distributed to the same server.

3. Load balancing configuration example
The following is a simple Nginx load balancing configuration example, using a polling algorithm to distribute requests to three back-end servers:

http {
  upstream backend {
    server 192.168.1.101;
    server 192.168.1.102;
    server 192.168.1.103;
  }

  server {
    listen 80;

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

In the above configuration, we defined the addresses of three backend servers through upstream. In the server block, configure the location to proxy the request to the backend server. By default, Nginx uses a round-robin algorithm to distribute requests to backend servers.

4. High-availability deployment solution
In order to ensure the high availability of the system, we can deploy Nginx using a master-slave structure or a hot backup structure.

1. Master-slave structure (Active-Passive)
   In the master-slave structure, there is a master server responsible for processing all requests, and the backup server will only take over the request when the master server fails. Automatic switching between master and slave servers can be achieved through the keepalived tool. The following is a configuration example of a master-slave structure:

http {
  upstream backend {
    server 192.168.1.101;
    server 192.168.1.102 backup;
  }

  server {
    listen 80;

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

In the above configuration, we added the backup keyword after the second server, indicating that the server will only be used when the main server is unavailable. Receive request.

2. Hot backup structure (Active-Active)
   In the hot backup structure, multiple servers are active and process requests at the same time, and the distribution of requests is achieved through soft load balancing. You can use LVS (Linux Virtual Server) or HAProxy to achieve load balancing. The following is a configuration example of a hot backup structure:

http {
  upstream backend {
    server 192.168.1.101;
    server 192.168.1.102;
  }

  server {
    listen 80;

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

In the above configuration, we defined two back-end servers and implemented load balancing through upstream. High-availability deployments can be achieved by configuring multiple servers and using load balancing algorithms.

Conclusion:
Nginx provides powerful load balancing and high availability deployment solutions. Through reasonable configuration, balanced utilization of resources and high availability of the system can be achieved. This article explains Nginx's load balancing and high availability deployment solutions in detail and provides corresponding code examples. I hope readers can use the guidance and examples in this article to build a high-availability and high-concurrency application architecture.

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