Скачать или смотреть Solving ResourceAccessException Issues with Keycloak in Spring Cloud Gateway using Docker-Compose

Learn how to resolve `ResourceAccessException` issues with Keycloak while using Spring Cloud Gateway in a Docker-Compose environment. Find effective solutions to configuration problems and streamline your application setup.
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Resolving the ResourceAccessException Issue with Keycloak in Spring Cloud Gateway using Docker-Compose

Developing microservices architecture often involves utilizing various components that need to work seamlessly together. One common challenge developers face is configuring these components within a containerized environment like Docker-Compose. A specific error that can arise in this context is the ResourceAccessException when interacting with Keycloak in a Spring Cloud Gateway application. In this guide, we’ll explore the problem and provide a detailed solution so you can get your application up and running smoothly.

The Problem

When running your Spring Cloud Gateway application alongside Keycloak and a Eureka server in a Docker-Compose environment, you may encounter the following error:

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While visiting the configuration URL directly in your browser may work perfectly, the application fails to access it when deployed in Docker. This is often caused by incorrect URI configuration in your Spring Cloud Gateway settings, particularly regarding how Docker networks resolve addresses.

Solution Overview

Understanding the Network Setup

In Docker-Compose, each service runs in its own container but those containers can communicate with each other using the network created by Docker. The default setup allows containers to refer to each other by name rather than using localhost or 127.0.0.1. This means you will need to adjust your configurations accordingly.

Step-by-Step Resolution

Follow these steps to resolve the ResourceAccessException issue:

Modify ISSUER_URI:
You need to change the ISSUER_URI from using 127.0.0.1 to the name of the Keycloak service. Here’s how you can do that:

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Remember that the port in this context is the container port, which is accessible within the Docker network.

Update Known Hosts:
To enable access to the Keycloak login page from your local machine or browser, add the following entry to your /etc/hosts file:

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This ensures that any attempt to access keycloak within your browser gets routed to the correct local address.

Updating your Docker-Compose Configuration

Here’s a concise view of what your relevant Docker-Compose snippet should look like post-modification:

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Final Thoughts

By adjusting the ISSUER_URI to use the Keycloak service name and ensuring that your local machine can resolve that service, you can eliminate the ResourceAccessException and successfully integrate Keycloak with your Spring Cloud Gateway application using Docker-Compose. This simple fix highlights the importance of understanding network configurations in containerized applications.

Following these guidelines will help you create a more robust microservices architecture, allowing for secure authentication flow through Keycloak without any hiccups. Happy coding!