Resolving Communications Exception in MySQL and Spring Boot on Kubernetes

Learn how to troubleshoot the `Communications link failure` error when connecting Spring Boot with MySQL in a Kubernetes environment, focusing on configuration adjustments and common pitfalls.
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Troubleshooting Communications Exception in Kubernetes with MySQL and Spring Boot

Understanding the Problem

While attempting to run a Spring Boot application using a MySQL database on Kubernetes, a communication failure indicates that the Spring Boot application cannot connect to the MySQL database service. Here are some key points related to the issue:

The mysql-docker-container is running, but the Spring Boot application throws an exception during initialization.

Changing configurations in the Docker environment to Kubernetes may create discrepancies, particularly with service ports and external access.

Solution Overview

The core of the problem lies in configuring the correct database connection URL to match the service's defined configuration in Kubernetes. Here’s how you can address this issue systematically:

1. Check Service Ports

The first thing to verify is the port settings for your MySQL service. In the provided configuration, you might have incorrectly referenced the service port in your Spring Boot application.

Current Configuration:

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Required Change:
Since the external port for the MySQL service is 3307, update the configuration as follows:

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This adjustment points to the right port that your Spring Boot application can connect through.

2. Verify Kubernetes Deployment Configurations

Make sure that your Kubernetes deployments and services are set correctly. Here’s what to check:

Deployment for MySQL:
Ensure that your MySQL deployment correctly exposes port 3306 internally, and your service is set up to reference it.

Service for MySQL:
Ensure the service configuration specifies the correct internal and external port mappings:

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3. Refresh and Redeploy

After making changes, don't forget to refresh your Kubernetes resources and redeploy them. You can use the follow commands for redeployment:

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4. Accessing the Application

To access your Spring Boot application correctly, use a proper NodePort if necessary. If you're encountering issues where services already exist, ensure you're either deleting existing services or using unique names for new ones:

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You can utilize the minikube service command to access the application URL.

Conclusion

By ensuring that your Spring Boot application is pointing to the correct MySQL service port and validating your Kubernetes configurations, you should be able to resolve the Communications link failure error. With these steps, you can smoothly establish a connection between your Spring Boot application and your MySQL database, promoting effective data storage and retrieval in your applications. Happy coding!