How to configure Nginx proxy server to limit the number of concurrent connections to a web service?

How to configure the Nginx proxy server to limit the number of concurrent connections to the web service?

Introduction:
With the development of Web applications, in order to ensure user experience and service stability, it is crucial to limit the number of concurrent connections of Web services. As a high-performance web server and reverse proxy server, Nginx provides a wealth of configuration options that can help us easily limit the number of concurrent connections. This article will introduce how to configure the Nginx proxy server to limit the number of concurrent connections for the web service and provide corresponding code examples.

1. Install Nginx:

First, we need to install Nginx. The following is a sample command to install Nginx on Ubuntu:

$ sudo apt update
$ sudo apt install nginx

2. Configure the Nginx proxy server:

1. Open the Nginx configuration file:

   $ sudo nano /etc/nginx/nginx.conf

2. Add the following configuration in the http block:

   http {
    ...
    
    # 限制并发连接数为100
    limit_conn_zone $binary_remote_addr zone=concurrent:10m;
    
    server {
        ...
        
        # 限制并发连接数为10
        limit_conn concurrent 10;
    
        ...
    }
   }

In the above example configuration, we used Nginx’s limit_conn module to limit the number of concurrent connections. Among them, limit_conn_zone is used to define a shared memory area to store status information about the number of concurrent connections, and sets a size of 10m; limit_conn is used to limit concurrency in each server block The number of connections is 10. You can adjust it according to actual needs.

3. Restart the Nginx service:

After completing the configuration, we need to restart the Nginx service to make the configuration take effect:

$ sudo systemctl restart nginx

4. Verify the configuration:

We can use the ab command to verify whether the configuration takes effect. The following is an example of using the ab command for stress testing:

$ ab -c 100 -n 1000 http://localhost/

In the above example, we set the number of concurrent requests to 100 through the -c parameter, the total number of requests to 1000 through the -n parameter, and the accessed URL is http ://localhost/. If the configuration takes effect, you will see output similar to the following:

Concurrency Level:      100
Time taken for tests:   10.000 seconds
Complete requests:      1000
Failed requests:        0
Total transferred:      158000 bytes
...

Conclusion:
By configuring the Nginx proxy server, we can easily limit the number of concurrent connections to the web service. The above configuration example can help you quickly implement this function. Of course, you may need to make some adjustments and modifications based on specific usage scenarios and needs. Hope this article is helpful to you!

Reference link:

• Nginx official documentation: https://nginx.org/en/docs/
• Nginx’s limit_conn module: https://nginx .org/en/docs/http/ngx_http_limit_conn_module.html

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