Spring Boot Security Google Oauth

In this series of tutorial, we will be integrating social login with spring boot application using spring security 5 provided features. In this particular tutorial, we will be adding google oauth login and custom registration support in a spring boot app and in coming articles we will be integrating other social platfom such as facebook, twitter and Github with it.

I have added custom registration on top of this article here - custom registration with Google OAuth

For a better understanding of spring security OAuth2 internals, We will be building this application with a very basic OAUTH2 integration with default configurations provided by spring security using oauth2Login() element and then customize it to a greater extent by adding custom login page, custom redirect-uri and UserService, token endpoint etc to extract user details such as name, email and profile image and use this information to generate JWT token out of it to authorize user for future server calls. We will also build an option available for a new user registration using email and password along with google oauth.

In my previous articles, we have discussed a lot about OAuth2 and it's principles and hence I will encourage you to go through those tutorials - Spring Security OAuth2 first to understand the basics of OAuth2 and then continue here.

What is OAuth2

OAuth2 is an authorization framework that enables applications to obtain limited access to user accounts on an HTTP service, such as Facebook, GitHub, and Google. It works by delegating user authentication to the service that hosts the user account, and authorizing third-party applications to access the user account. OAuth 2 provides authorization flows for web and desktop applications, and mobile devices.

Project Structure

First of all, we will generate the project with spring initializer(start.spring.io) as below and then add other required dependencies.

Maven Depenedencies

Apart from the default dependencies that were included during project initialization, we also require below dependencies.

<dependency>
	<groupId>org.springframework.security</groupId>
		<artifactId>spring-security-oauth2-client</artifactId>
</dependency>
<dependency>
	<groupId>org.springframework.security</groupId>
	<artifactId>spring-security-oauth2-jose</artifactId>
</dependency>
<dependency>
	<groupId>io.jsonwebtoken</groupId>
	<artifactId>jjwt</artifactId>
	<version>0.9.0</version>
</dependency>

Spring Security OAuth2 Config

Let us first use the default support provided by spring security 5 for OAuth2 and make our google OAuth sign in process successful as it requires bare minimum configurations. Doing so, we will not get confused after overriding the default implementation and build the final project.

Below is the security config that we require to get started with the OAuth in spring security. oauth2Login() in the below configuration enables all default configurations and makes all the resources protected. Only parameters it requires is the client-id and client-secret which we will be generating on google console in next section.

package com.devglan.springbootgoogleoauth.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;

@Configuration
@EnableWebSecurity(debug = true)
public class SecurityConfig extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.authorizeRequests().anyRequest().authenticated()
                .and()
                .oauth2Login();
    }

}

Now let us implement a test page - index.html. As we have protected all the resources, whenever we try to access index.html, we will be redirected to Google OAuth page and after successful authentication the index.html page will be served by spring boot.

<!doctype html>
<html lang="en">
<head>
    <meta charset="utf-8"/>
    <meta http-equiv="X-UA-Compatible" content="IE=edge"/>
    <title>Dashboard</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>
<div class="container">
    <h1>Welcome !</h1>
</div>
</body>
</html>

Google OAuth2 App Registration

Let us register our app on google developer console to get the client-id and cient-secret. As by default spring security 5 redirects user to {baseUrl}/{action}/oauth2/code/google post authentication, we have added

http://localhost:8080/login/oauth2/code/google

Once we have the client-id and client-secret, let us configure the same in our application.properties. Below entries in the application.properties is enough to run our application with default configuration.

spring.security.oauth2.client.registration.google.clientId=150677252870-78tlj6v2mm653alhodqr9t5br5fu5bs0.apps.googleusercontent.com
spring.security.oauth2.client.registration.google.clientSecret=ZptsDAPoVjn7DzVYbzSDNt1v

spring.datasource.url=jdbc:mysql://localhost:3306/test?useSSL=false
spring.datasource.username=root
spring.datasource.password=root
spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5InnoDBDialect

Testing Spring Security 5 OAuth2 Default Configuration

Whatever we have implemented above is enough to get started with a spring boot OAuth2 application. Spring boot has really made OAuth2 implementation very simple in a spring MVC app. Now, we can run SpringBootGoogleOauthApplication.java as a java application to test the application.

1. Hit localhost:8080/login or localhost:8080 and you will be forwarded to google sign in.

2. Now you can login to google(provider) and authorise this app.

3. Now you can see the index.html page rendered in your browser.

Spring Security Google OAuth2 Internals

The authentication process has been done now and the spring boot configuration looks very simple and straight forward but there are many things that happened in the background. Let us discuss each of them now.

When a request is made to localhost:8080 to access secured resource, spring security does not find any authenticated object in the context and redirects to

http://localhost:8080/oauth2/authorization/google

Now the request is redirected to

accounts.google.com/o/oauth2/v2/auth?response_type=code&client_id=150677252870-78tlj6v2mm653alhodqr9t5br5fu5bs0.apps.googleusercontent.com&scope=openid+profile+email&state=QFWkpSxvN-zs5gGoMCnFGDJDTYF1HZg1FC_5l31H0qg%3D&redirect_uri=http%3A%2F%2Flocalhost%3A8080%2Flogin%2Foauth2%2Fcode%2Fgoogle.

If the redirect_uri that we have configured in application.proprties does not match with the one that we have configured in google console, then you may see an error as Error: redirect_uri_mismatch

After a successful authentication with google and authorization of our app, the user will be redirected to '/login/oauth2/code/google with the authentication code as request param and this request will be intercepted by OAuth2LoginAuthenticationFilter. With this auth code, a POST request will be made to

https://www.googleapis.com/oauth2/v4/token

You can visit my another article for a better understanding of Spring Security filter chain and customization.

Below is a sample response from Google.

Principal: Name: [112360792925347143122], Granted Authorities: [ROLE_USER], User Attributes: [at_hash=TCTreSX3yj6ZB_T3TKTjRg, sub=112360792925347143122, email_verified=true, iss=https://accounts.google.com, given_name=Dhiraj, locale=en-GB, picture=https://lh4.googleusercontent.com/-jf-AkErib08/AAAAAAAAAAI/AAAAAAAAAwc/huSoFQWOXOk/s96-c/photo.jpg, aud=[150677252870-78tlj6v2mm653alhodqr9t5br5fu5bs0.apps.googleusercontent.com], azp=150677252870-78tlj6v2mm653alhodqr9t5br5fu5bs0.apps.googleusercontent.com, name=Dhiraj Ray, exp=2019-01-12T19:16:14Z, family_name=Ray, iat=2019-01-12T18:16:14Z, email=ssss@gmail.com]; Credentials: [PROTECTED]; Authenticated: true; Details: null; Granted Authorities: ROLE_USER

Customizing Spring Security oauth2Login()

Custom Redirection Endpoint

The Redirection Endpoint is used by the Authorization Server for returning the Authorization Response to the client. As we discussed above, we are using default redirection endpoint -

http://localhost:8080/login/oauth2/code/google

spring.security.oauth2.client.registration.google.redirect-uri=http://localhost:8080/oauth2/callback/google

protected void configure(HttpSecurity http) throws Exception {
        http.authorizeRequests().anyRequest().authenticated()
                .and()
                .oauth2Login()
                .redirectionEndpoint()
                .baseUri("/oauth2/callback/*");
    }

Custmomizing userInfoEndpoint()

Our custom user info endpoint will make request to the provider user info endpoint and retrieve the user info such as name, email, image etc. To do so, we need to implement OAuth2UserService. Spring boot provides two different implementation for this. We will be implementing OidcUserService for OpenID Connect (Google) providers.

For Facebook, we need to implement DefaultOAuth2UserService which we will implement in next article. The implenentaion will fetch the user info and creates entry in our local database. And we have already configured our MySql DB support for this app. Below is the implementation.

A call to super() will amke the REST call to fetch the userinfo from the external provider(Google). After a success response, the user entry will be created in our local system.

package com.devglan.springbootgoogleoauth.oauth2;

import com.devglan.springbootgoogleoauth.dao.UserRepository;
import com.devglan.springbootgoogleoauth.dto.GoogleOAuth2UserInfo;
import com.devglan.springbootgoogleoauth.model.User;
import com.devglan.springbootgoogleoauth.model.UserType;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.security.oauth2.client.oidc.userinfo.OidcUserRequest;
import org.springframework.security.oauth2.client.oidc.userinfo.OidcUserService;
import org.springframework.security.oauth2.core.OAuth2AuthenticationException;
import org.springframework.security.oauth2.core.oidc.user.OidcUser;
import org.springframework.stereotype.Service;

import java.util.Map;

@Service
public class CustomOidcUserService extends OidcUserService {

    @Autowired
    private UserRepository userRepository;

    @Override
    public OidcUser loadUser(OidcUserRequest userRequest) throws OAuth2AuthenticationException {
        OidcUser oidcUser = super.loadUser(userRequest);
        Map attributes = oidcUser.getAttributes();
        GoogleOAuth2UserInfo userInfo = new GoogleOAuth2UserInfo();
        userInfo.setEmail((String) attributes.get("email"));
        userInfo.setId((String) attributes.get("sub"));
        userInfo.setImageUrl((String) attributes.get("picture"));
        userInfo.setName((String) attributes.get("name"));
        updateUser(userInfo);
        return oidcUser;
    }

    private void updateUser(GoogleOAuth2UserInfo userInfo) {
        User user = userRepository.findByEmail(userInfo.getEmail());
        if(user == null) {
            user = new User();
        }
        user.setEmail(userInfo.getEmail());
        user.setImageUrl(userInfo.getImageUrl());
        user.setName(userInfo.getName());
        user.setUserType(UserType.google);
		userRepository.save(user);
    }
}

Below is our updated security config now.

protected void configure(HttpSecurity http) throws Exception {
        http.authorizeRequests().anyRequest().authenticated()
                .and()
                .oauth2Login()
                .redirectionEndpoint()
                .baseUri("/oauth2/callback/*")
                .and()
                .userInfoEndpoint()
                .oidcUserService(oidcUserService);
    }

package com.devglan.springbootgoogleoauth.dao;

import com.devglan.springbootgoogleoauth.model.User;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface UserRepository extends JpaRepository {

    User findByEmail(String email);
}

@Entity
@Table(name = "User")
public classUser {

    @Id
    @Column
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    private int id;
    @Column
    private String name;
    @Column
    private String email;
    @Column
    private String imageUrl;
    @Column
    private UserType userType;
	

Customizing Authorization Endpoint

oauth2Login().authorizationEndpoint() allows configuring the Authorization Endpoint. It is used by the client to obtain authorization from the resource owner via user-agent redirection.

oauth2Login()
.authorizationEndpoint()
                .baseUri("/oauth2/authorize")
                .authorizationRequestRepository(customAuthorizationRequestRepository());
				
@Bean
public AuthorizationRequestRepository customAuthorizationRequestRepository() {
	return new HttpSessionOAuth2AuthorizationRequestRepository();
}

At this point of time, if you try to run this application and follow above steps, you can see a new user entry in the DB.

Customizing Login Endpoint

By default, the OAuth 2.0 Login Page is auto-generated by the DefaultLoginPageGeneratingFilter. To override the default login page, configure oauth2Login().loginPage() and to start authentication with Google then you can redirect user to /oauth2/authorize/google. Here, /oauth2/authorize is the authorization endpoint that is configured above. You can visit this article for a Spring Security OAuth2 User Registration

@Override
protected void configure(HttpSecurity http) throws Exception {
	http
		.oauth2Login()
			.loginPage("/login/oauth2")
			...
			.authorizationEndpoint()
				.baseUri("/oauth2/authorize")
				....
}

Generating Custom JWT Token

To generate a custom JWT (Json Web Token) token, we require to overide the default AuthenticationSuccessHandler in spring security with our custom success handler. So far, our login process is done and now let us define our success handler. Inside the success handler we will be generating our JWT token.

While generating the JWT token, we will be re-using the features that we had developed in our previous article - Spring Boot JWT Auth.

@Component
public class CustomAuthenticationSuccessHandler extends SimpleUrlAuthenticationSuccessHandler {

    @Autowired
    private UserRepository userRepository;

    private String homeUrl = "http://localhost:8080/";

    @Override
    public void onAuthenticationSuccess(HttpServletRequest request, HttpServletResponse response, Authentication authentication) throws IOException, ServletException {
        if (response.isCommitted()) {
            return;
        }
        DefaultOidcUser oidcUser = (DefaultOidcUser) authentication.getPrincipal();
        Map attributes = oidcUser.getAttributes();
        String email = (String) attributes.get("email");
        User user = userRepository.findByEmail(email);
        String token = JwtTokenUtil.generateToken(user);
        String redirectionUrl = UriComponentsBuilder.fromUriString(homeUrl)
                .queryParam("auth_token", token)
                .build().toUriString();
        getRedirectStrategy().sendRedirect(request, response, redirectionUrl);
    }

}

Below is the implementation for generating JWT token. The implementation of JWT authentication in spring security is very much similar to this - . In next article, we will build the complete implementation of custom login with email and password and JWT token validation.

@Component
public class JwtTokenUtil implements Serializable {

    public static final long ACCESS_TOKEN_VALIDITY_SECONDS = 5*60*60;
    public static final String SIGNING_KEY = "devglan123r";

    public static String generateToken(User user) {
        Claims claims = Jwts.claims().setSubject(user.getEmail());

        return Jwts.builder()
                .setClaims(claims)
                .setIssuer("https://devglan.com")
                .setIssuedAt(new Date(System.currentTimeMillis()))
                .setExpiration(new Date(System.currentTimeMillis() + ACCESS_TOKEN_VALIDITY_SECONDS*1000))
                .signWith(SignatureAlgorithm.HS256, SIGNING_KEY)
                .compact();
    }

}

Conclusion

In this article, we implemented spring boot security google oauth and integrated JWT with it.Also, we looked into different ways we can customize the default behaviour of spring security 5 OAuth implementation. In the next article, we will be overriding the default login page and add support for custom login with email and password alng with JWT token validation.

I have added custom registration on top of this article here - custom registration with Google OAuth