Overview

User-agent in an incoming HTTP request is present in the headers of the request. In Go an incoming HTTP request is represented by the http.Request struct

https://golang.org/src/net/http/request.go

The http.Request struct exposes the below method for getting the user-agent of the request

func (r *Request) UserAgent() string

This method needs to be called on the request object.

Example

Let’s see the program for the same.

package main

import (
	"fmt"
	"net/http"
)

func main() {
	handler := http.HandlerFunc(handleRequest)
	http.Handle("/example", handler)
	http.ListenAndServe(":8080", nil)
}

func handleRequest(w http.ResponseWriter, r *http.Request) {

	userAgent := r.UserAgent()
	fmt.Printf("UserAgent:: %s", userAgent)
}

Run the above program and make the below API call. Also pass in the user-agent header

curl -v -X POST http://localhost:8080/example -H "user-agent: Mozialla -1.0"

Output

UserAgent:: Mozialla -1.0

In the above program, we are calling the UesrAgent() function on the request struct object and then printing it. It correctly prints the user agent