Golang : Set and Get HTTP request headers example

Couple of examples on how to set and get HTTP request headers in Golang.

Example of setting HTTP request header.

To set User-Agent for your Golang application, first create a client and set client's request header with [your user-agent name] before executing the request.

For instance :

  client := &http.Client{}
  request, err := http.NewRequest("GET", "http://example.com", nil)

 if err != nil {
  request.Header.Set("User-Agent", "[your user-agent name]")
  resp, err := client.Do(req)

Example of getting file download size

 response, err := http.Head(url)
 if err != nil {
 log.Println("Error while downloading", url, ":", err)
 length, _ := strconv.Atoi(response.Header.Get("Content-Length"))
 sourceSize := int64(length)

Example of getting HTTP request header User-Agent information with Header.Get() method

 package main

  import (

  func getUserAgent(w http.ResponseWriter, r *http.Request) {
 ua := r.Header.Get("User-Agent")
 fmt.Printf("user agent is: %s \n", ua)
 w.Write([]byte("user agent is " + ua))

  func main() {
 http.HandleFunc("/", getUserAgent)
 http.ListenAndServe(":8080", nil)

Apart from User-Agent, here is a list of common HTTP headers :















































References :




By Adam Ng

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