Solving the ECONNREFUSED Nightmare: NextJs Keycloak Auth in Docker Demystified

Are you tired of banging your head against the wall, trying to get NextJs Keycloak authentication to work in a Docker environment? Do the dreaded ECONNREFUSED errors haunt your every waking moment? Fear not, dear developer, for we’re about to embark on a journey to vanquish this beast and get your authentication up and running in no time!

What’s the Problem?

Before we dive into the solution, let’s understand what’s causing the issue in the first place. When you’re running a NextJs application with Keycloak authentication in a Docker container, the Keycloak server is typically running on a separate container or host. This means that the NextJs application needs to communicate with the Keycloak server to authenticate users.

The ECONNREFUSED error occurs when the NextJs application cannot establish a connection to the Keycloak server. This can happen due to various reasons, including:

• Keycloak server not running or not listening on the expected port
• Firewall or network configuration issues preventing communication between containers
• Mismatched or incorrect configuration in the NextJs application or Keycloak server
• Docker container networking issues

Prerequisites

Before we begin, make sure you have the following:

• A NextJs application set up with Keycloak authentication
• A Docker environment with Docker Compose (optional but recommended)
• A Keycloak server running on a separate container or host
• A basic understanding of Docker and Keycloak concepts

Solution: NextJs Keycloak Auth in Docker

Now that we’ve covered the basics, let’s get our hands dirty and fix this ECONNREFUSED issue once and for all!

Step 1: Verify Keycloak Server Configuration

First, ensure that the Keycloak server is running and listening on the expected port. You can do this by:

• Checking the Keycloak server logs for any errors or issues
• Verifying that the Keycloak server is listening on the correct port using tools like netstat or ss
• Accessing the Keycloak server’s admin console to ensure it’s functioning correctly

$ docker exec -it keycloak-server netstat -tlnp | grep 8080

Step 2: Update NextJs Application Configuration

Next, update your NextJs application’s configuration to point to the correct Keycloak server URL and port. You can do this by:

• Updating the next.config.js file to include the correct Keycloak server URL and port
• Verifying that the Keycloak realm and client ID are correctly configured

module.exports = {
  // ...
  auth: {
    keycloak: {
      realm: 'your-realm',
      clientId: 'your-client-id',
      url: 'http://keycloak-server:8080/auth',
    },
  },
};

Step 3: Configure Docker Networking

Now, let’s tackle the Docker networking issues that might be causing the ECONNREFUSED error. You can do this by:

• Creating a Docker network for your application using Docker Compose
• Updating the Docker Compose file to include the Keycloak server container
• Verifying that the NextJs application container can communicate with the Keycloak server container

version: '3'
services:
  nextjs-app:
    build: .
    ports:
      - "3000:3000"
    depends_on:
      - keycloak-server
    networks:
      - my-network

  keycloak-server:
    image: jboss/keycloak:latest
    ports:
      - "8080:8080"
    networks:
      - my-network

networks:
  my-network:
    driver: bridge

Step 4: Verify Connectivity and Test Authentication

Finally, let’s verify that the NextJs application can communicate with the Keycloak server and test the authentication flow. You can do this by:

• Accessing the NextJs application in a web browser
• Attempting to log in using valid credentials
• Verifying that the authentication flow completes successfully

Authentication Flow	Expected Outcome
Submit login credentials	Redirect to Keycloak server for authentication
Keycloak server authenticates user	Redirect back to NextJs application with access token
NextJs application verifies access token	Grant access to protected resources

Conclusion

And there you have it, folks! By following these simple steps, you should be able to overcome the ECONNREFUSED error and get your NextJs Keycloak authentication working seamlessly in a Docker environment.

Remeber to double-check your configuration, verify connectivity between containers, and test your authentication flow thoroughly to ensure a smooth user experience.

Happy coding, and may the authentication force be with you!

Keywords: ECONNREFUSED, NextJs, Keycloak, Docker, Authentication, Configuration, Troubleshooting

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