Golang Machine to Machine OAuth

main.go

package main

import (
	"context"
	"fmt"
	"golang.org/x/oauth2"
	"golang.org/x/oauth2/clientcredentials"
	"io/ioutil"
	"os"
)

/*
 * This app demonstrates a machine-to-machine ("two-legged") auth flow.
 *
 * We have a "Resource Server", https://spring.users.runpaste.com/. This Resource Server
 * is responsible for User Profiles, and has some scopes that it checks for like
 * "userprofile.edit". The resource server is registered in CloudEntity with the scopes
 * it exposes.
 *
 * In order for our application to consume services from the Resource Server, it gets registered
 * as a "Service" Client in CloudEntity. The client must be given access to the Scopes
 * exposed by the Resource server, e.g. userprofile.edit and userprofile.view.
 *
 * This client just needs a token url, client-id, and client-secret in order to make calls against the resource
 * server.
 *
 * See https://auth0.com/blog/using-m2m-authorization/
 */
func main() {
	fmt.Println("Demonstrating machine-to-machine authorization flow.")
	ctx := context.Background()

	// We register this application as a "Client" in CloudEntity (or Keycloak, or Okta, or...).
	// The client-id and client-secret are provided.
	conf := clientcredentials.Config{
		ClientID:       "",
		ClientSecret:   "",
		TokenURL:       "https://dmsi-poc.us.authz.cloudentity.io/dmsi-poc/spring/oauth2/token",
		Scopes:         []string{"userprofile.edit", "userprofile.view"},
		EndpointParams: nil,
		AuthStyle:      oauth2.AuthStyleInParams, // send client_id and client_secret as a form post
	}
	fmt.Printf("Using client_id %s\n", conf.ClientID)

	// The library gives us a *http.Client, which encapsulates the work of performing
	// the client-credentials flow to get an access token.
	client := conf.Client(ctx)

	// The Resource Server is configured to receive access tokens.
	resp, err := client.Get("https://spring.users.runpaste.com/users/123")
	if err != nil {
		fmt.Fprintf(os.Stderr, "%s ", err.Error())
		os.Exit(1)
	} else if resp.StatusCode != 200 {
		fmt.Fprintf(os.Stderr, "Status Code %s ", resp.StatusCode)
		os.Exit(1)
	}

	// Dump the results to stdout
	bytes, _ := ioutil.ReadAll(resp.Body)
	fmt.Println(string(bytes))
}