Go HTTP Proxy With Authentication

When using a proxy with authentication, the default HTTP request method does not allow for adding authorization headers post-request. This can pose challenges when integrating proxy support into existing third-party code.

In such scenarios, an alternative approach is to create a custom HTTP client with the required proxy configuration. This client can then be used in place of the default HTTP client in the third-party package.

Here's an example of how to create a custom HTTP client with proxy authentication using the http package:

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

// Create a proxy URL with authentication
proxyURL := &url.URL{
    Scheme: "http",
    User:   url.UserPassword("username", "password"),
    Host:   "proxy.com:8080",
}

// Create a custom HTTP client with the proxy
client := &http.Client{
    Transport: &http.Transport{
        Proxy: http.ProxyURL(proxyURL),
    },
}

// Use the custom client with the third-party package
resp, err := client.PostForm(method, params)
if err != nil {
    // Handle error
}

Alternatively, the URL can be parsed directly:

proxyURL, _ := url.Parse("http://username:[email protected]:8080")
client := &http.Client{
    Transport: &http.Transport{
        Proxy: http.ProxyURL(proxyURL),
    },
}

This method allows you to specify the necessary authentication credentials for the proxy within the client configuration.