50 Common Errors in Kubernetes

50 common errors in Kubernetes and some .
. tips on troubleshooting them:
1. Pod in CrashLoopBackOff:
o Check the pod logs using kubectl logs.

o Ensure the required dependencies are available.
2. ImagePullBackOff:
o Verify the image name and availability.

o Check image pull secrets and registry authentication.
3. Invalid ClusterIP or Service Port:
o Ensure correct service and port configurations.

o Verify network policies and firewall rules.
4. NodeNotReady:
o Check the node's status with kubectl get nodes.

o Examine the kubelet logs on the node.
5. Insufficient Resources:
o Confirm resource requests and limits in pod specifications.

o Use kubectl describe to analyze resource allocations.
6. CrashLoopBackOff for Init Containers:
o Inspect init container logs and configurations.

o Ensure init container dependencies are satisfied.
7. ConfigMap or Secret Mounting Issues:
o Verify ConfigMap/Secret existence and correctness.

o Check pod configuration for volume mounts.
8. Pod stuck in Pending state:
o Investigate resource constraints on the nodes.

o Examine events with kubectl describe pod.
9. API Server Unreachable:
o Verify API server status.

o Check kubeconfig file for correct API server address.
10. Network Policy Restrictions:
o Inspect network policies.

o Ensure correct podSelector and policy rules.
11. RBAC Permission Issues:
o Validate service account permissions.

o Check ClusterRoleBindings and RoleBindings.
12. PersistentVolumeClaims (PVC) Pending:
o Check available storage classes.

o Ensure the requested storage is available.
13. NodePort Service Not Accessible:
o Confirm the node's firewall allows the specified port.

o Check Service and NodePort configurations.
14. Kube-proxy Issues:
o Inspect kube-proxy logs for errors.

o Verify kube-proxy configuration.
15. DNS Resolution Problems:
o Verify CoreDNS status.

o Check DNS policy and cluster DNS settings.
16. Pod Eviction Due to Resource Pressure:
o Check resource usage across nodes.

o Adjust resource limits or add more nodes.
17. NodeOutOfMemory:
o Inspect node memory usage.

o Check for memory leaks in applications.
18. Volume Mount Permissions:
o Ensure correct file permissions in mounted volumes.

o Verify SELinux or AppArmor settings.
19. Ingress Controller Misconfiguration:
o Validate Ingress resource configurations.

o Check the Ingress controller logs.
20. ETCD Cluster Issues:
o Check etcd pod logs.

o Verify etcd cluster health.
21. CNI Plugin Issues:
o Verify CNI plugin status on nodes.

o Check plugin configurations and logs.
22. Invalid Labels or Selectors:
o Ensure correct labels and selectors in resources.

o Use kubectl get with appropriate labels.
23. Pod Security Policies:
o Check PodSecurityPolicy (PSP) violations.

o Adjust PSP or use PodSecurity admission controllers.
24. Kubelet Certificate Rotation:
o Monitor kubelet certificate expiration.

o Rotate certificates if needed.
25. Cluster Autoscaler Issues:
o Verify autoscaler configuration.

o Check node group scaling policies.
26. ServiceAccount Token Expiration:
o Ensure service account tokens are not expired.

o Rotate service account tokens if needed.
27. Scheduler Issues:
o Inspect scheduler logs for errors.

o Check for node affinity and anti-affinity issues.
28. Readiness and Liveness Probe Failures:
o Review pod configurations for probes.

o Check probe logs and adjust thresholds.
29. Inconsistent API Versions:
o Verify client and server API versions match.

o Use compatible kubectl versions.
30. Kube-dns Service Missing:
o Ensure CoreDNS (or kube-dns) service is running.

o Validate DNS settings in kubelet configurations.
31. ImageRegistryAuthentication:
o Check image pull secrets in pod specifications.

o Verify registry credentials.
32. HorizontalPodAutoscaler Not Scaling:
o Check metrics server and HPA configurations.

o Inspect HPA events and logs.
33. Pod Affinity/Anti-affinity Issues:
o Verify pod affinity/anti-affinity rules.

o Check node labels for affinity.
34. Custom Resource Definitions (CRD) Issues:
o Validate CRD creation and versions.

o Check for CRD controller errors.
35. Resource Quotas Exceeded:
o Review resource quotas with kubectl describe.

o Adjust quotas or request more resources.
36. RuntimeClass Configuration Issues:
o Verify RuntimeClass in PodSpec.

o Check container runtime compatibility.
37. Secrets Decoding Errors:
o Validate encoded secrets.

o Ensure proper base64 encoding.
38. Invalid Ingress Controller Configuration:
o Inspect Ingress controller logs.

o Verify controller configurations.
39. Pod Priority and Preemption Issues:
o Check priorityClass in PodSpec.

o Verify kube-scheduler settings.
40. Node Network Connectivity Issues:
o Check node network configurations.

o Verify firewall rules on nodes.
41. Service External IP Not Assigned:
o Check cloud provider integration.

o Verify LoadBalancer service configurations.
42. PodSecurityContext Misconfigurations:
o Validate pod security context settings.

o Ensure compatibility with node settings.
43. Kubelet Certificate Rotation Issues:
o Monitor and rotate kubelet certificates.

o Verify certificate expiration dates.
44. Volume Plugin Not Loaded:
o Check kubelet logs for volume plugin errors.

o Verify plugin installation and configuration.
45. NetworkPolicy Not Enforced:
o Check NetworkPolicy existence.

o Inspect podSelector and policy rules.
46. Image Vulnerability Scanning Failures:
o Integrate image scanning tools.

o Ensure scanning results are reviewed.
47. Pods Stuck in Terminating State:
o Check for stuck processes in containers.

o Examine pod logs for termination issues.
48. Invalid Pod Restart Policy:
o Verify restartPolicy in PodSpec.

o Adjust policy if necessary.
49. Incorrect Ingress Path Matching:
o Check path specifications in Ingress rules.

o Verify backend service configurations.
50. NodeDrain Failures:
o Check node drain status with kubectl drain.

o Investigate any evicted pods.
When troubleshooting, it's crucial to gather information from various sources such as
logs, events, and configuration files. Use kubectl describe, kubectl logs, and relevant
logs from components like kubelet, kube-proxy, and controllers. Additionally,
monitoring tools and dashboards can help identify patterns and trends in the
cluster's behavior.

50 Common Errors in Kubernetes

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50 Common Errors in Kubernetes

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50 common errors in Kubernetes and some .

. tips on troubleshooting them:

o Check the pod logs using kubectl logs.

o Verify the image name and availability.

3. Invalid ClusterIP or Service Port:

o Ensure correct service and port configurations.

o Check the node's status with kubectl get nodes.

o Confirm resource requests and limits in pod specifications.

o Inspect init container logs and configurations.

7. ConfigMap or Secret Mounting Issues:

o Verify ConfigMap/Secret existence and correctness.

8. Pod stuck in Pending state:

o Investigate resource constraints on the nodes.

9. API Server Unreachable:

o Verify API server status.

10. Network Policy Restrictions:

o Inspect network policies.

11. RBAC Permission Issues:

o Validate service account permissions.

o Check available storage classes.

13. NodePort Service Not Accessible:

o Confirm the node's firewall allows the specified port.

14. Kube-proxy Issues:

o Inspect kube-proxy logs for errors.

15. DNS Resolution Problems:

o Verify CoreDNS status.

16. Pod Eviction Due to Resource Pressure:

o Check resource usage across nodes.

o Inspect node memory usage.

o Ensure correct file permissions in mounted volumes.

19. Ingress Controller Misconfiguration:

o Validate Ingress resource configurations.

20. ETCD Cluster Issues:

o Check etcd pod logs.

21. CNI Plugin Issues:

o Verify CNI plugin status on nodes.

22. Invalid Labels or Selectors:

o Ensure correct labels and selectors in resources.

23. Pod Security Policies:

o Check PodSecurityPolicy (PSP) violations.

o Monitor kubelet certificate expiration.

25. Cluster Autoscaler Issues:

o Verify autoscaler configuration.

26. ServiceAccount Token Expiration:

o Ensure service account tokens are not expired.

27. Scheduler Issues:

o Inspect scheduler logs for errors.

28. Readiness and Liveness Probe Failures:

o Review pod configurations for probes.

29. Inconsistent API Versions:

o Verify client and server API versions match.

o Ensure CoreDNS (or kube-dns) service is running.

o Check image pull secrets in pod specifications.

32. HorizontalPodAutoscaler Not Scaling:

o Check metrics server and HPA configurations.

33. Pod Affinity/Anti-affinity Issues:

o Verify pod affinity/anti-affinity rules.

34. Custom Resource Definitions (CRD) Issues: