Why troubleshooting skills are critical in Kubernetes - Why It Works

Introduction

Troubleshooting skills help you find and fix problems in your Kubernetes clusters quickly. Without these skills, small issues can cause big disruptions in your applications and services.

When a pod is stuck in a pending or crash loop state and you need to find out why

When your application is not reachable and you want to check if the service or network is the problem

When resource limits cause pods to be evicted and you want to adjust settings

When deployments fail to roll out and you need to see error messages

When logs show errors but you need to connect them to cluster events or configurations

Commands

This command lists all pods in the current namespace so you can see their status and identify any that are not running properly.

Terminal

kubectl get pods

Expected Output

NAME             READY   STATUS             RESTARTS   AGE

my-app-pod       0/1     CrashLoopBackOff   3          5m

This command shows detailed information about the pod, including events and reasons for failures, helping you understand why the pod is crashing.

Terminal

kubectl describe pod my-app-pod

Expected Output

Name:           my-app-pod

Namespace:      default

Status:         CrashLoopBackOff

Events:

  Type     Reason     Age                    From               Message

  ----     ------     ----                   ----               -------

  Warning  BackOff    2m (x3 over 5m)        kubelet            Back-off restarting failed container

This command fetches the logs from the pod's container to see error messages or output that explain why the application inside the pod is failing.

Terminal

kubectl logs my-app-pod

Expected Output

Error: failed to connect to database

Connection refused

This command lists recent cluster events sorted by time, helping you spot issues like scheduling failures or resource problems affecting your pods.

Terminal

kubectl get events --sort-by=.metadata.creationTimestamp

Expected Output

LAST SEEN   TYPE      REASON             OBJECT           MESSAGE

1m          Warning   FailedScheduling   pod/my-app-pod   0/3 nodes are available: 3 Insufficient memory.

→

--sort-by=.metadata.creationTimestamp - Sort events by time to see the latest issues first

Key Concept

If you remember nothing else from this pattern, remember: troubleshooting is about gathering clues step-by-step to find the root cause of problems in your Kubernetes cluster.

Common Mistakes

Ignoring pod status and jumping straight to logs

Pod status and events often give quick clues about resource or scheduling issues that logs alone won't show.

Always check pod status and describe output before looking at logs.

Not checking recent cluster events

Events provide context about why pods fail to start or get scheduled, which logs might not reveal.

Use 'kubectl get events' sorted by time to find recent problems.

Assuming the problem is inside the application without checking Kubernetes resources

Sometimes the issue is with resource limits, node availability, or network policies, not the app code.

Check pod status, events, and resource usage before blaming the application.

Summary

Use 'kubectl get pods' to check pod status and spot problems quickly.

Use 'kubectl describe pod' to get detailed info and events about a pod's issues.

Use 'kubectl logs' to see application errors inside the pod.

Use 'kubectl get events' to find cluster-wide issues affecting pods.