I am simple Spring MVC application which secured by Spring Security. Instead of using simple form based security, I am secured by Spring Security OAuth2 and the OAuth provider is Google.

Developing a Spring MVC web application with Security enabled and integrated with Google is hard to implement. So this is a sample implementation of Spring MVC + Spring Security OAuth2 + Google Provider.

The project is built with Gradle so you can run the build using the following gradle command gradle clean build

To start up the application using the following command (Since it is a Spring boot application) gradle bootRun

The application.properties (in src/main/resources) contains the details of the Google application which it uses to authenticate details. Change the values of the following attributes to the values for your application google.client.id google.client.secret

###To register a Google App perform the following steps

• Go to https://console.developers.google.com and login with your Google account (this will be the developer account and the email of this account will be published when someone tries to authenticate with the Google application)
• If you don't have a project create a new one and then click into the project.
• In the menu on the left side select "APIs & auth" --> "Credentials" --> "Create a new client ID"
• In the popup select the following
  • Application Type = Web Application
  • Authorized Javascript Origins = ,
  • Authorized Redirect URI = , the URI for our application is /googleLogin so for local testing you should enter http://localhost:9000/googleLogin and http://localhost:9000/googleLogin/ on different lines.
  • Copy the client ID and client Secret and update the application.properties
• Make sure you update the mandatory values on the "APIs & auth" --> "Consent screen" page as the application will not work without it.

When you have a the Google App configured and the Spring boot application and you navigate to http://localhost:9000. It will redirect you to a Google login page. Upong login it will ask you to authorize your application for access to your account to get email and profile data. On successful login it will render the basic HTML page which means the authentication was sucessful.

If you are interested in fetching the Google profile data in type in the following URL http://localhost:9000/find?term=hello in the authenticated browser session and the profile data will be logged in the console of the Spring application.

It is important to use the correct filters from Spring Security OAuth2 to get this right and it is also very important to get their order right.

The filters oauth2ClientContextFilter and oAuth2AuthenticationProcessingFilter are very important the their position in the chain is equally important. oauth2ClientContextFilter must exist before oAuth2AuthenticationProcessingFilter. Also both these must be before the FILTER_SECURITY_INTERCEPTOR so that the authentication with google is complete before we check for the security permissions for access to the application.

Also the authentication entry point of the secured application is clientAuthenticationEntryPoint which essentially redirects the user to the configured url /googleLogin when the user is not authenticated. When the url /googleLogin is hit the filters listed above lead to a redirect to the Google URL. Upon authentication, Google redirects back to us and the filter populates the Authentication object.

After all the authentication is complete, the request is redirected back to http://localhost:9000. This request will hit the FILTER_SECURITY_INTERCEPTOR but the session is already authenticated and the Security Context is populated so access to the application is granted by the interceptor and the session is authentication.

If you want to see the profile data, in an authenticated session (since the resource uses the OAuth2RestOperations) a GET to http://localhost:9000/find?term=hello will display the profile data on the web application console. See the src/main/java/com/rst/oauth2/google/api/UserResource.java for implementation details.