What is the purpose of proxy_pass in nginx?

In nginx, the proxy_pass directive is used to forward client requests to a specified backend server. It is a key directive for implementing reverse proxy.

When nginx receives a request from a client, it can use the proxy_pass directive to forward that request to a specified backend server, and then pass the response from the backend server back to the client. This way, the client does not need to communicate directly with the backend server, but instead goes through nginx as an intermediary for request forwarding and response returning.

The proxy_pass directive is used to configure the address of the backend server, including the IP address and port number. Typically, protocols such as http, https, socks4, and socks5 can be used to communicate with the backend server. When configuring proxy_pass, other parameters can also be specified, such as proxy_set_header for setting request header information and proxy_connect_timeout for setting connection timeout.

With the proxy_pass directive, nginx can achieve load balancing, caching, implementing HTTPS, and reverse proxy, among other functions. It can improve the performance and security of applications while also offering flexibility and scalability, making it suitable for various types of use cases.