ackage auth provides painless OAuth2 authentication for http handlers.

After creating an Auth object, the RedirectHandler should be mounted to answer the cfg.OAuth2.RedirectURL http calls and the Authenticate method can be used to enforce authentication on http handlers. The User function can be used to get the logged in user in an authenticated http handler.

See simple usage example in ./example/main.go.

a, err := auth.New(ctx, auth.Config{ ... })
if err != nil { /* Handle error */ }

mux := http.NewServeMux()
mux.Handle("/", a.Authenticate(handler))  // Authenticate a given handler on '/'.
mux.Handle("/auth", a.RedirectHandler())  // Handle OAuth2 redirect.
log.Fatal(http.ListenAndServe(":8080", mux)) // Serve.

Authentication is done by wrapping an http.Handler that requires only signed in users with the Authenticate middleware method.

Authorization is allowing only specific users to access an http.Handler. For example, allowing only [email protected], or anyone that signed in using their @example.com. This can be done by inspecting the username using the auth.User(ctx) method, inside the authenticated http.Handler. For example, given a function authorized that checks if the signed-in user is authorized:

func handler(w http.ResponseWriter, r *http.Request) {
	creds := auth.User(r.Context())
	if !authorized(creds) {
		// Handle unauthorized users.
		http.Error(w, "User not allowed", http.StatusForbidden)
		return
	}
	// Handle authorized users.
}

// authorized is an example function that checks if a user is authorized.
func authorized(creds *auth.Creds) bool { return creds.Email == "[email protected]" }

• Automatic redirects to OAuth2 flow (login screen) from authorized handlers when user is not authenticated.

• Redirect handler automatic redirects to the path that requested to the authentication. Such that if user visited /foo and was sent to the OAuth2 login. After successfull login it will return to /foo.

• Auth2 id_token is automatically stored in a Cookie. This allows users not to go through the authentication phase on every authenticated page, or on different sessions.

• example: The example program shows how to use the auth package.

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