Kubernetes is the current leader in container orchestration platforms. As it brings a wide range of features to the table, including scalability, self-healing, storage, secrets management, and more. However, due to its intricacy, this powerful solution can be complex sometimes. Let us explores some lesser-known areas of troubleshooting in real-world circumstances to help you deal with the complexities and improve your Kubernetes experience.
What is Kubernetes Troubleshooting?
Kubernetes troubleshooting is the process of discovering, diagnosing, and fixing problems in Kubernetes clusters, pods, nodes, or containers.
Kubernetes troubleshooting, in a broader sense, also involves good continuous fault management and adopting preventative steps in Kubernetes components.
Why is Kubernetes Troubleshooting so difficult?
When it comes to troubleshooting difficulties inside a cluster, Kubernetes, being a complicated system, provides its own set of obstacles. Even with a modest, local Kubernetes configuration, identifying and resolving problems can be difficult since a problem might arise from a single container, one or more pods, a controller, a control plane component, or even many entities at the same time.
The complexity only grows in large-scale manufacturing operations, where poor visibility and a plethora of moving components make troubleshooting a daunting task. Teams are juggling many tools to obtain the necessary data for inquiry, and more tools may be required to successfully diagnose, and fix found issues.
Moreover, Kubernetes is widely used to construct microservices apps, each microservice developed by a different team. In certain cases, both DevOps and app development teams operate in one Kubernetes cluster, confusing the division of duties. When an issue with a pod emerges, determining whether it is the responsibility of DevOps, or the related application team can be difficult.
In short, unless teams synchronize their efforts and have access to the correct set of tools, Kubernetes troubleshooting may quickly spiral into a chaotic situation, consuming considerable resources and negatively harming users and application operation.
Common Causes Behind App Errors
When it comes to apps malfunctioning or breakdowns on Kubernetes, some faults seem to reappear regularly. If you have ever encountered apps that were deployed but weren’t working, chances are they were caused by one of the following issues:
- The application is listening to the wrong ports.
- The app is listening on the incorrect interface (for example, localhost rather than 0.0.0.0).
- The app was incorrectly configured.
- The app is unable to read or write a file on a disc, typically owing to missing directories or insufficient permissions.
While this does not account for every possible error, it does allow for a considerable fraction of them.
Troubleshooting Kubernetes Apps
Let’s look at a common Kubernetes application architecture to help you efficiently debug Kubernetes applications. If you have problems with your application deployment, you should look at three major areas:
- Check the Pods
- Test the Service
- Examine the Route or Ingress
Check the pods
The initial step should be to examine the app by checking the Pod that is executing your container. Consider the following troubleshooting suggestions:
- Begin by running the following command to verify the status of the Pod: kubectl get pods <pod name>
- Next, examine your Pod’s logs with: kubectl logs <pod name>
Pay extra attention to any error-level logs or warnings because they frequently disclose useful information. If the Pod repeatedly restarts or fails, the logs might provide valuable information about the root reason.
While studying the logs, consider the following questions:
- Is there a configuration file missing from the app? Consider utilizing a ConfigMap or Secret to provide custom configurations.
- Is the application trying to connect to a service that does not exist? Check the database URLs and API endpoints for correctness.
- Is the application trying to connect to another service but using the wrong credentials?
Test the app from within the Pod by using a command-line HTTP client such as ‘curl’ or ‘wget’:
curl localhost:8080
If the application fails to generate the desired results, carefully read the error message and check the logs for any probable problems.
Test the Service
The Service is crucial in Kubernetes as the load-balancing object. It allows your app to be accessible throughout the cluster. However, it is quickly misconfigured. Here’s what you need to do:
- Determine the service name for your application by using:
kubectl get svc - Now, test the functioning of the Service by looking at it from another Pod using:
curl http://myappservice:8080Make sure that you can access the application without any problems. - Then, check the Service configuration with:
kubectl, describe svc …Check that it is accurately pointing to the ports on your Pod.
Common Issues with Kubernetes Services:
The following are some frequent reasons why a Service may not function as expected:
- The Service is directing traffic to the incorrect ports.
- The labels in your Deployment or DeploymentConfig do not match the Service selection.
This is an important step that should not be overlooked since it might expose any misconfigurations affecting the functioning of your app.
Inspect the Route or Ingress:
If you can access the application from outside the cluster, you’re presumably doing so using a Route or an Ingress. In this step, we will verify if you can use the application from the desktop:
- Try accessing the application in a web browser (for web apps) or using curl to view the endpoint of your app (for APIs).
- If the request times out or you are unable to access the application, there may be a problem with the Route or Ingress settings.
Use the following command to learn more:
kubectl, describe ingress …
Or, for OpenShift users:
oc, describe route …
What often causes issues with Kubernetes Routes and Ingresses?
Networking problems might vary greatly; however, the following are frequent causes of external access issues:
- When using an HTTPS-only route, make sure to use ‘https://’ rather than ‘http://’
- Incorrect Service Mapping: For accurate Service mapping, inspect the Ingress or Route configuration
- If there are troubles with the underlying router, contact your cluster administrator
Conclusion
To summarise, debugging or troubleshooting an application on Kubernetes can be intimidating. But the simplest approach is to divide it down into sections and verify each one individually.
- Check that the application is functioning properly and responding to requests by attempting to enter the Pod, run a test, or view its logs
- Ensure that your Service can be reached from other Pods
- Inspect your network’s Ingress or Route
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