How to implement request forwarding function in Golang

Golang request forwarding refers to the method of implementing the request forwarding function in the Golang language. Request forwarding refers to forwarding requests from the client to other servers for processing, and then returning the processing results to the client. Request forwarding allows front-end pages to access resources on different servers, thereby improving the availability and scalability of web applications. In this article, we will introduce how to implement request forwarding function in Golang.

1. Application scenarios of request forwarding

In actual development, we often need to share data or perform tasks between multiple servers and multiple applications. Request forwarding can distribute client requests to multiple servers for processing, improving resource utilization and response speed. Request forwarding is also an important tool for building distributed applications. Whether in the form of load balancing or proxy servers, requests can be distributed through request forwarding.

2. Method to implement request forwarding

2.1 Using HTTP proxy

In Golang, you can use the ReverseProxy structure in the net/http package to achieve this HTTP proxy to achieve request forwarding. The ReverseProxy structure can forward the received request to other URLs for processing, and return the result to the client after processing. The following is a sample code using ReverseProxy:

   package main

   import (
       "net/http"
       "net/http/httputil"
       "net/url"
   )

   func main() {
       proxy := httputil.NewSingleHostReverseProxy(&url.URL{
           Scheme: "http",
           Host:   "localhost:8080",
       })
       http.ListenAndServe(":80", proxy)
   }

In this sample code, we first create a proxy object proxy and set the request address to http://localhost:8080. Then, we bind the proxy object to the HTTP server by calling the http.ListenAndServe function, listen on port 80, and wait for client requests. When a client request is received, the proxy object will forward the request to the backend address for processing, and finally return the processing result to the client.

2.2 Using polling to implement load balancing

Another common request forwarding implementation method is request forwarding based on load balancing. Load balancing refers to distributing client requests to multiple servers so that the server load is as even as possible and improves the availability and scalability of the system. In Golang, a polling algorithm can be used to achieve load balancing and evenly distribute client requests to multiple servers.

The following is a sample code that uses polling to achieve load balancing:

   package main

   import (
       "fmt"
       "io/ioutil"
       "log"
       "math/rand"
       "net/http"
       "net/url"
       "time"
   )

   // 定义所有可用的服务器列表
   var proxyList = []string{
       "http://localhost:8080",
       "http://localhost:8081",
       "http://localhost:8082",
   }

   func main() {
       proxy := &Proxy{
           urls:      make([]*url.URL, 0),
           current:   0,
           transport: &http.Transport{},
       }
       for _, p := range proxyList {
           u, _ := url.Parse(p)
           proxy.urls = append(proxy.urls, u)
       }
       // 监听80端口
       if err := http.ListenAndServe(":80", proxy); err != nil {
           panic(err)
       }
   }

   type Proxy struct {
       urls      []*url.URL
       current   int
       transport *http.Transport
   }

   func (p *Proxy) ServeHTTP(w http.ResponseWriter, r *http.Request) {
       // 随机获取一台服务器
       u := p.urls[p.current]
       p.current = (p.current + 1) % len(p.urls)

       // 设置协议和主机
       r.Header.Set("X-Forwarded-Host", r.Header.Get("Host"))
       r.Header.Set("X-Forwarded-Proto", "http")
       r.URL.Scheme = u.Scheme
       r.URL.Host = u.Host

       // 发送请求
       res, err := p.transport.RoundTrip(r)
       if err != nil {
           log.Printf("%s", err)
           w.WriteHeader(http.StatusInternalServerError)
           return
       }
       defer res.Body.Close()

       // 将结果返回给客户端
       for k, v := range res.Header {
           w.Header().Set(k, v[0])
       }
       w.WriteHeader(res.StatusCode)
       body, err := ioutil.ReadAll(res.Body)
       if err != nil {
           log.Printf("%s", err)
           w.WriteHeader(http.StatusInternalServerError)
           return
       }
       fmt.Fprintf(w, "%s", body)
   }

In this sample code, we first define a proxy object proxy, which contains all available server addresses list. Then, we bind the proxy object to the HTTP server by calling the http.ListenAndServe function, listen on port 80, and wait for client requests. When a client request is received, the proxy object randomly selects a server for processing and sends the request to that server. After processing is complete, the proxy object returns the results to the client.

3. Summary

In this article, we introduced two methods to implement request forwarding function in Golang language: using HTTP proxy and load balancing based request Forward. HTTP proxy is a common request forwarding implementation method that can forward requests to other servers for processing, thereby improving resource utilization and response speed. Load balancing is a practical and practical method of request forwarding. It can distribute client requests to multiple servers to make the server load as even as possible and improve the availability and scalability of the system. Whether using HTTP proxy or load balancing, the request forwarding function can be implemented to improve the availability and scalability of web applications.

The above is the detailed content of How to implement request forwarding function in Golang. For more information, please follow other related articles on the PHP Chinese website!