Скачать или смотреть Solving 401 Unauthorized Errors in Spring Boot with Keycloak in Docker

Discover solutions to the `401 Unauthorized` errors encountered in Spring Boot applications deployed in Docker when using Keycloak for authentication.
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Understanding the 401 Unauthorized Problem in Spring Boot with Keycloak in Docker

If you've been working with Spring Boot and Docker, you might have encountered a frustrating issue: receiving a 401 Unauthorized status code when attempting to access secured endpoints, even when valid JWTs (JSON Web Tokens) are provided. This issue often puzzles developers since everything works perfectly fine when the Spring Boot application is run outside of Docker, making it difficult to pinpoint the root cause of the problem.

In this post, we will dive deep into understanding why this happens and how to resolve it. We'll cover the configurations that are critical when deploying Spring Boot applications in Docker, specifically when integrating them with Keycloak for authentication.

Identifying the Cause of the 401 Status Code

The 401 Unauthorized response typically indicates that the authentication failed for some reason. The most common reasons in this scenario include:

Mismatch in the issuer URI for the JWT

Incorrect configuration in your Docker setup

Keycloak not responding correctly in the container environment

How to Fix the Issue

To resolve the 401 Unauthorized error, there are several steps you need to follow. We'll break these down into clear sections below:

1. Verify the Issuer URI

One of the most important aspects to check is the issuer URI defined in your Spring configuration. The value of security.oauth2.resourceserver.jwt.issuer-uri must match exactly the value of the iss claim in the access tokens issued by Keycloak. Pay attention to the following:

Exact match: The scheme (HTTP/HTTPS) and trailing slash (if any) are both important. For instance:

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Make sure that the KEYCLOAK_URL is correctly pointing to your Keycloak container.

2. Set the Hostname in Keycloak Configuration

You can enhance your Keycloak configuration by specifying the hostname property. This setting will ensure that the hostname is properly set in the issuer URI for all tokens issued by Keycloak, which can resolve issues related to mismatched URIs. Here’s how you can define it in your docker-compose.yaml:

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3. Specify the JWK Set URI

If you find that the issuer URI can’t be resolved or reached from your resource server's network, you may need to explicitly define the jwk-set-uri. This is crucial if Keycloak returns JWTs that have JWKs (JSON Web Keys) that are not automatically guessed based on the issuer-uri. Add this to your application properties as follows:

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4. Review Docker Configuration

Lastly, ensure that your Docker setup is correctly managing the dependencies. Check your docker-compose.yaml configuration and ensure that:

The keycloak container is correctly configured and is running on the appropriate ports.

Your Spring Boot schedule-service is depending on the keycloak service to start successfully.

Conclusion

Encountering a 401 Unauthorized error when deploying your Spring Boot application in Docker while using Keycloak can be challenging. However, by closely examining the issuer URI, ensuring proper hostname settings, and configuring your JWT correctly, you can resolve this issue effectively.

By following these steps, you can create a smooth authentication experience for your users and ensure that your Spring Boot application works seamlessly with Keycloak in a containerized environment. If you continue to experience issues, double-check your configurations and look for network issues between services in your Docker network.

Happy coding, and may you never receive another 401 Unauthorized error again!