Refactoring HTTP Request execution

main.go

package main

import (
	"bytes"
	"encoding/json"
	"io/ioutil"
	"log"
	"net/http"
	"net/http/httputil"
)

type authRequest struct {
	UserName string `json:"username"`
	Password string `json:"password"`
}

type authResponse struct {
	Token string
}

type configRequest struct {
	ID string `json:"id"`
}

type configResponse struct {
	Foo string
}

// HTTP Bin post method returns the posted body in a data attribute
type httpBinResponse struct {
	Data string `json:"data"`
}

func main() {
	token, err := getAuthToken()
	if err != nil {
		log.Fatal(err)
	}

	config, err := getConfig("foo", token)
	if err != nil {
		log.Fatal(err)
	}

	_ = config
}

func buildRequest(endpoint string, body interface{}, extraHeaders map[string]string) (*http.Request, error) {
	jsnBytes, err := json.Marshal(body)
	if err != nil {
		return nil, err
	}

	req, err := http.NewRequest("POST", endpoint, bytes.NewReader(jsnBytes))
	if err != nil {
		return nil, err
	}

	req.Header.Add("Content-Type", "application/json")

	for name, value := range extraHeaders {
		req.Header.Add(name, value)
	}

	dump, err := httputil.DumpRequest(req, true)
	if err != nil {
		return nil, err
	}

	log.Println("Request: ", string(dump))

	return req, nil
}

func executeRequest(req *http.Request, responseBody interface{}) error {
	client := http.Client{}
	log.Println("Initiating http request")

	resp, err := client.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	bytes, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return err
	}

	log.Printf("Response is: %s\n", string(bytes))
	var httpBinJSON httpBinResponse
	err = json.Unmarshal(bytes, &httpBinJSON)
	log.Printf("Unmarshalled response: %s\n", httpBinJSON)

	return err
}

func getAuthToken() (string, error) {
	endpoint := "https://httpbin.org/post"

	req, err := buildRequest(endpoint, authRequest{
		UserName: "foo",
		Password: "bar",
	}, nil)

	if err != nil {
		return "", err
	}

	var resp authResponse
	return "", executeRequest(req, &resp)
}

func getConfig(id string, token string) (*configResponse, error) {
	endpoint := "https://httpbin.org/post"

	req, err := buildRequest(endpoint, configRequest{ID: id}, map[string]string{
		"Authorization": "Bearer " + token,
	})

	if err != nil {
		return nil, err
	}

	var config configResponse
	err = executeRequest(req, config)

	if err != nil {
		return nil, err
	}

	return &config, nil
}