Spring Boot Web Application with OpenID Connect Authentication

This is a Spring Boot web application that demonstrates OpenID Connect authentication using Keycloak. The application has two endpoints:

1. A public endpoint accessible to everyone
2. A protected endpoint accessible only to authenticated users

Features

• Spring Boot 3.1.5
• Spring Security with OpenID Connect
• Thymeleaf templates for the frontend
• Bootstrap 5 for styling

Pages

• Home Page: Publicly accessible. Greets authenticated users by name.
• User Page: Protected page accessible only to authenticated users. Displays user information.
• Login Page: Provides a link to authenticate with Keycloak.

Prerequisites

• Java 17 or higher
• Gradle
• Keycloak server (for OpenID Connect authentication)

Running the Application

1. Clone the repository
2. Configure Keycloak (see below)
3. Update application.properties with your Keycloak settings
4. Run the application:

   ./gradlew bootRun
   

5. Access the application at http://localhost:8080

Configuring Keycloak

1. Install and start Keycloak
2. Create a new realm (e.g., webapp2-realm)
3. Create a new client:
   • Client ID: webapp2-client
   • Client Protocol: openid-connect
   • Access Type: confidential
   • Valid Redirect URIs: http://localhost:8080/*
4. After creating the client, go to the "Credentials" tab to get the client secret
5. Create a user in the realm
6. Update the application.properties file with your Keycloak settings:

   spring.security.oauth2.client.registration.keycloak.client-id=webapp2-client
   spring.security.oauth2.client.registration.keycloak.client-secret=your-client-secret
   spring.security.oauth2.client.provider.keycloak.issuer-uri=http://localhost:8180/auth/realms/webapp2-realm
   

Application Structure

• Main.java: Spring Boot application entry point
• HomeController.java: Controller for the public endpoint
• UserController.java: Controller for the protected endpoint
• SecurityConfig.java: Security configuration for OpenID Connect
• templates/home.html: Home page template
• templates/user/home.html: User page template
• templates/login.html: Login page template
• application.properties: Application configuration

Notes

• The application uses Spring Security's OAuth2 client support for OpenID Connect authentication
• Thymeleaf templates use Bootstrap 5 for styling
• The application includes debug logging for Spring Security to help with troubleshooting