How to implement HTTP request retry and timeout handling in Go?

In Go, you can implement HTTP request retry and timeout handling using the net/http package along with the built-in time package. Here is an example of how to achieve this:

Start by defining a function to send the HTTP request, handle retries, and handle timeouts:

import (
	"net/http"
	"time"
	"fmt"
)

func sendRequestWithRetryAndTimeout(url string, retries int, timeout time.Duration) (*http.Response, error) {
	client := http.Client{
		Timeout: timeout,
	}

	for i := 0; i <= retries; i++ {
		resp, err := client.Get(url)

		// Retry if the request failed
		if err != nil {
			fmt.Printf("Request attempt %d failed: %s\n", i, err)
			continue
		}

		// Retry if the response status code is an error
		if resp.StatusCode >= 400 {
			fmt.Printf("Request attempt %d returned status code: %d\n", i, resp.StatusCode)
			resp.Body.Close()
			continue
		}

		// Request succeeded
		return resp, nil
	}

	return nil, fmt.Errorf("maximum retries exceeded")
}

Usage example, where you specify the number of retries and the timeout duration:

func main() {
	url := "https://example.com"
	retries := 3
	timeout := time.Second * 5

	resp, err := sendRequestWithRetryAndTimeout(url, retries, timeout)
	if err != nil {
		fmt.Println("Error:", err)
		return
	}

	fmt.Println("Response:", resp.Status)
}

In the above example, the sendRequestWithRetryAndTimeout function sends an HTTP GET request to the specified URL with the provided number of retries and timeout. It retries the request if there is an error or if the response status code is an error (e.g., 4xx or 5xx). If the maximum number of retries is exceeded, it returns an error.