org.postgresql.util.PSQLException: Connection attempt failed: Dockerized Spring Boot Applications

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Troubleshooting PostgreSQL Connection Issues in Dockerized Spring Boot Applications

Understanding the Problem

You might be working with a setup consisting of multiple services. In this case, the setup includes:

Zookeeper: Manages Kafka brokers.

Kafka: An event streaming platform.

Spring Boot Application: Your main application that interacts with both Kafka and PostgreSQL.

PostgreSQL: The database storing your application’s data.

The error message indicates that your Spring Boot application cannot connect to the PostgreSQL database. This issue can occur for various reasons, but let's dive into the most common one related to container networking.

Identifying the Cause

Network Configuration

In Docker, each container operates in its own network. If you want different containers to communicate with one another, they must be on the same Docker network. In your setup, the Spring Boot application and PostgreSQL database are likely not on the same network. This disconnect is what's preventing your application from accessing the database.

Docker Compose Configuration

Let's look at your Docker Compose file to identify this problem:

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

In the current configuration, the PostgreSQL service does not define a network, leading to the connection failure.

Solution: Ensuring Network Connectivity

Step 1: Define Networks for PostgreSQL

To ensure that your Spring Boot application can communicate with your PostgreSQL database, you need to include the same network configuration for PostgreSQL. Here’s how you should modify the Docker Compose file:

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

By adding networks: - my_network, you ensure that the postgres container can now communicate with the springboot-app container.

Step 2: Optional - Use depends_on

While not strictly necessary, adding a depends_on clause helps manage startup order, ensuring that the database is up and running before the Spring Boot application tries to connect:

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

This addition is a good practice and can help prevent connection attempts before the database is fully available.

Conclusion

Now that the configuration is set up correctly, you should no longer encounter connection issues, allowing you to focus on developing your application further. With Docker, managing multiple services is simpler than ever, as long as the network configuration is appropriately handled!

If you have any questions or run into other issues while using Docker with Spring Boot, feel free to ask in the comments below!