How can I read the header from an http request in golang?

Question

If I get a request like http.Request, how can I read the value of a specific header? In this case, I want to pull the jwt token value from the request header.

Answer 1

You can use r.Header.Get :

func yourHandler(w http.ResponseWriter, r *http.Request) {
    ua := r.Header.Get("User-Agent")
    ...
}

Answer 2

package main

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

func main() {
    http.HandleFunc("/", handler)
    log.Fatal(http.ListenAndServe("localhost:8000", nil))
}

func handler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "%s %s %s \n", r.Method, r.URL, r.Proto)
    //Iterate over all header fields
    for k, v := range r.Header {
        fmt.Fprintf(w, "Header field %q, Value %q\n", k, v)
    }

    fmt.Fprintf(w, "Host = %q\n", r.Host)
    fmt.Fprintf(w, "RemoteAddr= %q\n", r.RemoteAddr)
    //Get value for a specified token
    fmt.Fprintf(w, "\n\nFinding value of \"Accept\" %q", r.Header["Accept"])
}

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Connecting to http: // localhost: 8000 / from the browser will print the output in the browser.