How to Implement Single Sign-On Using OAuth in Golang Applications

How to Implement SSO Using OAuth in Golang Application

Single Sign On (SSO) is a popular authentication approach used by many companies, especially those with multiple applications and services. Implementing SSO using OAuth in a Golang application is possible, but requires some additional work. This tutorial will show you how to build an OAuth-based Golang application that is capable of authenticating users through SSO.

Why SSO?

SSO is a great way for organizations to streamline authentication for their users. By using a single authentication process, organizations can reduce the complexity of the authentication process, as well as eliminate the need for users to remember multiple credentials. Additionally, SSO can provide stronger security than other authentication methods, as it provides a single point of authentication for all services.

What is OAuth?

OAuth is an open source authorization protocol used for securely providing access to third party services. OAuth allows users to grant access to a third party application without giving them the username and password credentials. OAuth is the most commonly used protocol for implementing SSO systems.

Building the Auth Handler in Go

To implement SSO using OAuth, you will need to develop an authorization handler in Go. The authorization handler is responsible for exchanging OAuth tokens with the authentication provider and validating user identity.

First, you need to set up the authorization handler. Create a struct that stores the OAuth configuration and store the OAuth token:

type AuthHandler struct {
    // OAuth configuration
    Config *oauth2.Config
    // OAuth token
    Token *oauth2.Token
}

Next, create a function that will handle the OAuth flow. This function will receive the user’s authorization code from the authentication provider and exchange it for an OAuth token. Once it has the token, it will validate the token and store it in the AuthHandler’s Token field.

func (handler *AuthHandler) HandleAuthFlow(authCode string) error {
    // Exchange authorization code for OAuth token
    token, err := handler.Config.Exchange(context.TODO(), authCode)
    if err != nil {
        return err
    }
    // Validate OAuth token
    if err := handler.Config.CheckToken(token); err != nil {
        return err
    }
    // Store token
    handler.Token = token
    return nil
}

Finally, create a function that will return the OAuth token when requested. This will allow our application to use the token when making authorized requests:

func (handler *AuthHandler) GetToken() (*oauth2.Token, error) {
    return handler.Token, nil
}

Integrating the Auth Handler into Your Go App

Once you have built the AuthHandler, you will need to integrate it into your application. You will need to set up routes that can receive the authorization code from the authentication provider and call the AuthHandler to exchange it for an OAuth token. When these routes are triggered, the AuthHandler will process the request and exchange the authorization code for an OAuth token.

You will also need to set up routes to validate the OAuth token and handle any errors that might arise during the token validation process. You can use the CheckToken method from the OAuth library to validate the token. Your application should also be able to handle any errors thrown by the CheckToken method and appropriately respond to the user.

Conclusion

In this tutorial, you learned how to implement SSO using OAuth in a Golang application. You saw how to build an AuthHandler that is capable of exchanging authorization codes for OAuth tokens and validating them. You also saw how to incorporate the AuthHandler into your application by setting up the appropriate routes. With this knowledge, you should now be able to build a Golang application that can securely authenticate users with SSO.