How to Successfully Dockerize Your Corda Spring Boot Server

A step-by-step guide to resolving connection issues when running a Corda Spring Boot server in a Docker container.
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How to Successfully Dockerize Your Corda Spring Boot Server

In the world of modern application development, containerization has become a crucial practice. However, transitioning your applications to a containerized approach can come with its own set of challenges. Recently, a developer faced a significant hurdle: running a Corda Spring Boot server within a Docker container. In this guide, we will explore how to address this problem and ensure seamless communication between your Spring Boot server and Corda nodes.

The Problem: Connection Issues

You might find yourself in a situation similar to the one described by the developer who wished to run both Corda nodes and a Spring Boot server in Docker containers. Despite creating a functioning docker-compose file and Docker image for the Spring Boot server, they encountered a troubling connection error:

Error Message:
Caused by: net.corda.client.rpc.RPCException: Cannot connect to server(s). Tried with all available servers.

This error indicates that while the containers were running, the Spring Boot server failed to connect with the Corda node. So, what went wrong?

Understanding the Issue

Key Points to Consider:

Networking in Docker: Docker containers can communicate with each other through a network. If the container settings are misconfigured, they may not be able to find each other.

Host and Port Configuration: The server's host and port configuration is crucial for establishing a connection. Incorrect settings or mismatched network configurations can cause connection failures.

The Solution: Fixing Connection Issues

After identifying the problem, the developer managed to resolve the issue. Here’s how you can approach the same solution:

Step 1: Review Your Docker Configuration

Ensure that your docker-compose.yml file correctly defines the network settings. When containers are placed on a bridge network, they can communicate with each other using their container names.

Check the service names in your Docker Compose file to ensure they align with what is specified in your Spring Boot application configuration.

Step 2: Correct Host and Port Names

Confirm that the host (typically the service name within the Docker Compose file) and the port specified in your Spring Boot application match exactly with those used by the Corda node.

For example, if the Corda node is running on port 10003, make sure your Spring Boot application attempts to connect to that port on the correct host.

Step 3: Redeploy Your Containers

After making the necessary changes:

Rebuild your Docker images using docker-compose build.

Bring up your containers again using docker-compose up.

Step 4: Test Connectivity

Once your containers are running, test the connection:

You can utilize tools such as curl or Postman to test the endpoint exposed by your Spring Boot server to confirm it can communicate with the Corda node.

Conclusion

Dockerizing applications, especially ones as complex as Corda Spring Boot servers, can lead to various challenges. In essence, ensuring proper host and port configuration within your Docker environment is vital for enabling communication between containers. Following the steps outlined above, you should be well-equipped to troubleshoot and rectify any connection issues, allowing your Spring Boot server and Corda nodes to work harmoniously in a Docker environment.

By addressing the host and port discrepancies and leveraging Docker's networking capabilities, the developer successfully resolved their connectivity issues. Now, both applications are working together as intended.

Happy Dockerizing!