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 {
log.Fatalln(err)
}
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 (
"fmt"
"net/http"
)
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 :
"accept"
"accept-charset"
"accept-encoding"
"accept-language"
"accept-ranges"
"age"
"access-control-allow-origin"
"allow"
"authorization"
"cache-control"
"content-disposition"
"content-encoding"
"content-language"
"content-length"
"content-location"
"content-range"
"content-type"
"cookie"
"date"
"etag"
"expect"
"expires"
"from"
"host"
"if-match"
"if-modified-since"
"if-none-match"
"if-unmodified-since"
"last-modified"
"link"
"location"
"max-forwards"
"proxy-authenticate"
"proxy-authorization"
"range"
"referrer"
"refresh"
"retry-after"
"server"
"set-cookie"
"strict-transport-security"
"transfer-encoding"
"user-agent"
"vary"
"via"
"www-authenticate"
References :
https://www.socketloop.com/references/golang-net-http-canonicaheaderkey-function-example
https://www.socketloop.com/tutorials/golang-how-to-get-http-request-header-information
https://www.socketloop.com/tutorials/golang-how-to-set-or-add-header-http-responsewriter
By Adam Ng
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