Debug if pod fails to create in Kubernetes

When a pod fails to create in Kubernetes, you can follow these steps to debug the issue

1. Check the pod status:

kubectl get pods

Example output:

NAME     READY     STATUS                RESTARTS   AGE
my-pod   0/1      ContainerCreating       0              5s

In this example, the pod is in the ContainerCreating status, indicating a failure during container creation

2. Inspect pod events:

kubectl describe pod

Example command:

kubectl describe pod my-pod

Look for events or errors in the output that provide information about the failure. Common issues include scheduling errors, image pulling failures, or resource constraints.

3. Examine pod logs

kubectl logs <pod-name>

Example command:

kubectl logs my-pod

This command retrieves the logs from the pod’s containers. If there are multiple containers in the pod, specify the container name with the --container <container-name> flag.

4. Verify resource availability: Check if the requested resources (CPU, memory, storage) are available in the cluster. Insufficient resources can prevent pod creation. Review the pod’s YAML file to ensure the resource requests and limits are appropriate.

5. Review container image and image pull secrets: Verify that the container image specified in the pod’s YAML file exists and is accessible. If it’s a private registry, ensure the necessary image pull secrets are configured:

kubectl get secrets

Example command to view image pull secrets:

kubectl get secrets -o wide

6. Check cluster network and DNS:

Ensure the cluster’s networking and DNS configurations are functioning properly. DNS resolution issues can prevent pod creation. Test DNS resolution:

kubectl exec -it -- nslookup google.com

Example command:

kubectl exec -it my-pod -- nslookup google.com

7. Validate pod configuration: Double-check the pod’s YAML file for syntax errors or misconfiguration. Use a YAML validator to ensure the file is correctly structured.

8. Review cluster-level settings: Check for any cluster-level configurations or limitations that may affect pod creation, such as PodSecurityPolicies, resource quotas, admission controllers, or custom controllers.

9. Consult Kubernetes logs and cluster monitoring: Review Kubernetes cluster logs and monitoring tools (e.g., Prometheus, Grafana) to identify any cluster-wide issues or errors that might impact pod creation.

10. Seek help from Kubernetes community: If you’re unable to resolve the issue, seek assistance from the Kubernetes community forums, GitHub issues, or relevant user groups. Provide detailed information about the error, pod configuration, and cluster setup for better assistance.