Get app authentication access token for the Twitter API in Golang

twitter_get_access_tok.go

package main

import b64 "encoding/base64"
import "encoding/json"

type BearerToken struct {
    Token_Type string
    Access_Token string
}

func main() {
    var tok BearerToken

    req, err := http.NewRequest("POST", "https://api.twitter.com/oauth2/token", strings.NewReader("grant_type=client_credentials"))

    if err != nil {
        log.Fatal(err)
    } else {

        data := os.Getenv("CONSUMER_KEY") + ":" + os.Getenv("CONSUMER_SECRET")
        b64_token := b64.StdEncoding.EncodeToString([]byte(data))

        // log.Printf("%s", b64_token)

        req.Header.Add("Authorization", "Basic " + b64_token)
        req.Header.Add("Content-Type", "application/x-www-form-urlencoded;charset=UTF-8")

        access_tok_client := &http.Client{}

        resp, err := access_tok_client.Do(req)

        if err != nil {
            log.Fatal(err)
        } else {            
            bearer, err := ioutil.ReadAll(resp.Body)
            if err != nil {
                log.Fatal(err)
            } else {
                err := json.Unmarshal(bearer, &tok)

                if err != nil {
                    log.Fatal(err)
                } else {
                    log.Printf("%s", tok.Access_Token)
                }
            }
        }
    }

    log.Printf("Access token: %s", tok.Access_Token);
}