Build Authenticated Applications Locally with the Keycloak Extension for LocalStack

Testing authentication locally can be complex, often requiring a running identity provider, token validation by Lambda functions, and API Gateway authorization enforcement. To address these challenges, a Keycloak extension for LocalStack has been developed, enabling Keycloak to run alongside emulated AWS services, facilitating local testing of the full authentication flow without external dependencies. Keycloak is an open-source identity and access management solution supporting OAuth 2.0, OpenID Connect, and SAML 2.0, providing a server with features like a management console and token issuance. Running Keycloak as a LocalStack extension simplifies the setup by integrating authentication services within the LocalStack environment, allowing for direct communication between Lambda functions and Keycloak, and ensuring a fresh Keycloak instance with each LocalStack restart. This setup allows for offline development and testing of OAuth2/OIDC flows. The process involves installing the extension, deploying a sample application using API Gateway, Lambda, and DynamoDB with Keycloak for JWT-based authorization, and testing the API endpoints with role-based access control using Keycloak JWTs.