Securing FastAPI with Keycloak

FastAPI is known for its performance and ease of use, making it a great match with Keycloak, a robust identity and access management solution. This blog will guide you through integrating FastAPI with Keycloak to secure your REST endpoints effectively.

Flow:

1. Client Credentials Request: The CLI application uses a Service Account and sends a request to Keycloak as a client_credentials grant type along with Service account credentials. The Keycloak server validates this request and grants an access token to the CLI application.
2. Token Issuance: Keycloak verifies the service account credentials and, if successful, issues an access token to the CLI application.
3. Authorization Request: The CLI application includes the obtained access token in the Authorization header of an HTTP GET request to access the /secure-data endpoint on the FastAPI server.
4. Token Validation (Server-side): When FastAPI receives the request, the token needs to be validated. To do this, FastAPI fetches the public key (JWKS) from Keycloak, which is necessary to verify the token's signature.
5. Secure Data Access: If the token is valid and the service account has the necessary permissions, FastAPI processes the request and returns the secure data with a 200 OK response.