Setting Up Keycloak with PostgreSQL in Docker Compose: Resolving Database Relation Conflicts

Learn how to successfully integrate Keycloak with a PostgreSQL database using Docker Compose, avoiding common errors related to database relations.
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Setting Up Keycloak with PostgreSQL in Docker Compose: Resolving Database Relation Conflicts

In the world of application development, managing authentication and authorization can be complex. Keycloak is a popular tool for handling this, but integrating it with an existing PostgreSQL database can sometimes lead to headaches, especially when using Docker Compose. A common issue developers face is conflicting database tables—specifically, trying to create tables that already exist in your database. In this post, we'll explore this issue and how to resolve it effectively.

The Problem

You have an existing Docker Compose setup that initializes a PostgreSQL database and runs several SQL scripts to set up necessary relations for your application. However, when adding Keycloak to the mix, you encounter an error indicating that the table named client already exists within your PostgreSQL schema. This happens because Keycloak attempts to create its own version of the client table, which leads to a conflict with your existing database relations.

Error Encountered

The error message you might see looks something like this:

[[See Video to Reveal this Text or Code Snippet]]

This means Keycloak is trying to create a table that already exists in your database setup, which results in a failure during the database migration process.

The Solution: Use Separate Databases for Keycloak and Your Application

To avoid this type of conflict, the best approach is to use separate PostgreSQL databases—or at least separate schemas—within the same PostgreSQL instance for your application and Keycloak. This way, both systems can function independently without interfering with one another's data structures.

Step-by-Step Guide to Implementing the Solution

Step 1: Modify Your Docker Compose File

You will need to update your Docker Compose file to accommodate two separate databases. Here’s how to do it:

Define Multiple Databases:
You can specify separate databases for Keycloak and your application within your PostgreSQL service.

Update the Keycloak Service:
Point the Keycloak service to its designated database.

Here is an example of what your Docker Compose file should resemble after the necessary modifications:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Create the Keycloak Database

Before starting your containers, ensure that you create the Keycloak database separately in your PostgreSQL instance. You can do this with a SQL command like:

[[See Video to Reveal this Text or Code Snippet]]

Replace your_keycloak_database_name with the corresponding environment variable you have set in your Docker Compose file, e.g., ${POSTGRESQL_KEYCLOAK_DATABASE}.

Step 3: Run Your Docker Compose Setup

Once your Docker Compose file is updated and your databases are set up, run your application using the following command:

[[See Video to Reveal this Text or Code Snippet]]

This command will start all services defined in your Docker Compose file, and Keycloak will now be able to connect to its dedicated database without causing any conflicts.

Conclusion

By using separate databases or schemas for Keycloak and your existing application, you can effectively avoid the relation already exists errors in your PostgreSQL setup. This structure allows each service to operate independently, ensuring smoother integration and development workflows. If you encounter any issues during your setup, revisiting your Docker Compose configurations and database management strategies can help resolve them efficiently.

Now you're ready to integrate Keycloak seamlessly with your application while leveraging the powerful features of PostgreSQL in Docker!