Getting Started with Spring Boot Social Authentication

Spring Boot Social auth

Spring Boot social auth makes it possible for users to authenticate into Spring Boot applications using their existing social accounts. Using Spring Boot social authentication allows developers to major in business logic rather than majoring in developing a custom authentication system.

Prerequisites

Before we continue you will need the following:

1. Java developer kit JDK installed on your computer.
2. Knowledge of Kotlin programming language.
3. Knowledge of the Spring Boot framework.

Creating the application

We are going to use Spring initializr to create our Spring Boot application.

• Navigate to Spring initializr in your browser.
• Select Kotlin in the languages section.
• Add Spring Web, OAuth2 Client, and Spring Boot DevTools dependencies.
• Leave other configurations as default and click on generate the project.
• Unzip the downloaded project and open it in your favorite IDE. I will be using Intelij IDEA community which is available for free.
• Sync the project with maven to download and all the dependencies.

Adding webjar dependencies

Since we are going to need Jquery to build the frontend for our application, we need to add webjar dependencies to make Jquery available in our Spring Boot project.

In the pom.xml add the dependencies below to include Jquery in our project.

      <dependency>
            <groupId>org.webjars</groupId>
            <artifactId>jquery</artifactId>
            <version>3.4.1</version>
        </dependency>
        <dependency>
            <groupId>org.webjars</groupId>
            <artifactId>bootstrap</artifactId>
            <version>4.3.1</version>
        </dependency>
        <dependency>
            <groupId>org.webjars</groupId>
            <artifactId>webjars-locator-core</artifactId>
        </dependency>

Spring security configuration

1. In the project’s root package, create a package named config.
2. Inside the config package created above, create a new kotlin file named WebConfig and add the code snippets below.

import org.springframework.context.annotation.Configuration
import org.springframework.http.HttpStatus
import org.springframework.security.config.annotation.web.builders.HttpSecurity
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter
import org.springframework.security.core.AuthenticationException
import org.springframework.security.web.authentication.AuthenticationEntryPointFailureHandler
import org.springframework.security.web.authentication.HttpStatusEntryPoint
import javax.servlet.http.HttpServletRequest
import javax.servlet.http.HttpServletResponse

@Configuration
class WebConfig : WebSecurityConfigurerAdapter() {
    @Throws(Exception::class)
    override fun configure(http: HttpSecurity) {
        http
            .authorizeRequests { a ->
                a.antMatchers("/", "/error", "/webjars/**").permitAll()
                    .anyRequest().authenticated()
            }
            .exceptionHandling { e ->
                e.authenticationEntryPoint(HttpStatusEntryPoint(HttpStatus.UNAUTHORIZED))
            }
            .oauth2Login { o ->
                o.failureHandler { request: HttpServletRequest, response: HttpServletResponse?, exception: AuthenticationException ->
                    request.session.setAttribute("error.message", exception.message)
                    val handler: AuthenticationEntryPointFailureHandler? = null
                    assert(false)
                    handler!!.onAuthenticationFailure(request, response, exception)
                }
            }
    }
}

• @Configuration annotation marks the class as a Spring Boot configuration class.
• .authorizeRequests { a -> a.antMatchers("/", "/error", "/webjars/**").permitAll() .anyRequest().authenticated() } permits all the requests made to /, /error and /webjars/** endpoints. All the requests made to the above endpoints don’t require user authentication.
• oauth2Login { o -> o.failureHandler { request: HttpServletRequest, response: HttpServletResponse?, exception: AuthenticationException -> request.session.setAttribute("error.message", exception.message) val handler: AuthenticationEntryPointFailureHandler? = null assert(false) handler!!.onAuthenticationFailure(request, response, exception) } } handles any exception that occurs during the authentication process, i.e, when a user cancels social auth dialog or inputs the wrong social credentials.

Spring Social auth controller

1. In the root project package, create a new package named controller.
2. In the package created above, create a new file named SocialController.kt and add the code snippet below.

@RestController
@RequestMapping("/api/v1/")
class SocialController {

    @GetMapping("/user")
    fun user(@AuthenticationPrincipal principal: OAuth2User): Map<String, Any?>? {
        return Collections.singletonMap("name", principal.getAttribute("name"))
    }
}

• user function returns the username from the social authentication provider that the user has logged in with.

Github authentication

To use GitHub’s OAuth 2.0 authentication in our application as a login system, we must create a new Github application. On the page presented, select a New OAuth App and register the application.

Set http://localhost:8080/login/oauth2/code/github as the authorization callback URL and http://localhost:8080 as the homepage for the application.

Now that we have created a Github OAuth application, create a file named application.yml in the resources directory and add the code snippets below into the file.

Replace github-client-id and github-client-secret with the credentials you obtained from the Github OAuth application created above.

spring:
  security:
    oauth2:
      client:
        registration:
          github:
            clientId: github-client-id
            clientSecret: github-client-secret

Navigate to http://localhost:8080 in your browser, you will be presented with a GitHub authentication screen as shown below.

Google authentication

Now that we have successfully implemented Github authentication, let’s also implement Google authentication.

In the application.yml file we created above, add the Google auth code snippet from the google auth section in the code snippet below.

To obtain Google OAuth 2.0 credentials, follow the instructions here. Replace google-client-id and google-client-secret with the credentials you obtained from the google OAuth 2.0 dashboard.

spring:
  security:
    oauth2:
      client:
        registration:
          # github auth section
          github:
            clientId: github-client-id
            clientSecret: github-client-secret
          # google auth section
          google:
            client-id: google-client-id
            client-secret: google-client-secret

Homepage

In this section, we are going to create a simple HTML for our homepage.

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <title>Demo</title>
    <meta name="description" content="" />
    <meta name="viewport" content="width=device-width" />
    <base href="/" />
    <link
      rel="stylesheet"
      type="text/css"
      href="/webjars/bootstrap/css/bootstrap.min.css"
    />
    <script type="text/javascript" src="/webjars/jquery/jquery.min.js"></script>
    <script
      type="text/javascript"
      src="/webjars/bootstrap/js/bootstrap.min.js"
    ></script>
  </head>
  <body>
    <h1>Demo</h1>
    <div class="container"></div>
    <div class="container unauthenticated">
      <div>
        With GitHub: <a href="/oauth2/authorization/github">click here</a>
      </div>
      <div>
        With Google: <a href="/oauth2/authorization/google">click here</a>
      </div>
    </div>

    <div class="container authenticated" style="display:none">
      Logged in as: <span id="user"></span>
    </div>
    <!-- Grabs the username from  /api/v1/user endpoint and displays it in the span with the id #user-->
    <script type="text/javascript">
      $.get('/api/v1/user', function (data) {
        $('#user').html(data.name);
        $('.unauthenticated').hide();
        $('.authenticated').show();
      });
    </script>
  </body>
</html>

When you navigate to http://localhost:8080, the web page below is displayed.

On clicking Google auth the app redirects to the Google authentication screen as shown below.

After successful authentication, a user is redirected to the homepage where their username is captured from the social profile. The screenshot below shows a username captured from the Google authentication.

Conclusion

Now that you have learned how to authenticate users in your Spring Boot application through Google and Github, implement Facebook social authentication in your Spring Boot application.

The source code for the application can be found here.

Happy coding.

Peer review contribution by: Linus Muema