Скачать или смотреть How to Fix Spring Boot Readiness Probe Failures on Kubernetes

Learn how to resolve the `Spring Boot readiness probe` failures that cause pod restarts on Kubernetes by adjusting the liveness probe settings.
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Resolving Spring Boot Readiness Probe Failures on Kubernetes

If you're a developer managing Kubernetes pods, you might have faced the frustrating issue of Spring Boot readiness probes failing. This can cause numerous pod restarts, leading to instability in your application. In this guide, we will explore a common problem encountered with Spring Boot applications deployed on Kubernetes and provide a comprehensive solution to avert these issues.

Understanding the Problem

When deploying a Spring Boot application, you may configure both liveness and readiness probes to monitor the health of your app. A developer reported an issue with their minimal Spring Boot app, where the readiness probe was accessible on localhost but failed when the app was deployed on Minikube. The error looked something like this in the pod description:

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This error resulted in multiple pod restarts, leading to significant downtime until the pods finally stabilized. Despite verifying that the app logs showed no errors, the problem persisted, triggering a thorough investigation into the root cause.

Investigating the Configuration

Let's take a look at important sections of the Spring Boot application's configurations that may impact the probes:

1. Service Manifest

The service manifest defines how the application is exposed within the Kubernetes cluster. Here's a simplified excerpt:

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2. Deployment Manifest

This specifies the deployment settings for the pods, which include essential probe configurations:

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3. Application YAML Configuration

Your application.yaml governs how the Spring Boot application behaves, especially concerning health checks:

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The Solution to Pod Restarts

After conducting thorough research and experimentation, the resolution to mitigate the pod restarts lies in adjusting the liveness probe configuration by adding an initialDelaySeconds. Here’s the step-by-step fix:

1. Modify Liveness Probe Configuration

To solve the problem, you simply need to include the initialDelaySeconds in your liveness probe settings, just as you have in the readiness probe. Here’s how your deployment manifest should look:

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2. Apply the Changes

After updating your Kubernetes manifest files, ensure to apply the changes by executing:

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3. Monitor the Pods

Once the new settings are applied, you can monitor the pods to ensure they stabilize and the readiness probe starts working correctly without triggering unnecessary restarts.

Conclusion

By adjusting the initialDelaySeconds in the liveness probe configuration, you can effectively prevent unnecessary pod restarts for your Spring Boot application running on Kubernetes. This adjustment allows your application sufficient time to initialize before Kubernetes health checks commence, leading to a more stable deployment.

Implementing these small yet significant changes can improve your application's uptime and reliability on Kubernetes. If you find yourself facing similar issues, consider this an essential step in your deployment configurations!

If you have further questions or need assistance with your Spring Boot deployment, feel free to leave a comment!