Understanding Kubernetes CreateContainerError

Ever feel like everything is going smoothly, and then suddenly, a big panda walks in and crashes your day?

That's what dealing with CreateContainerConfigError in Kubernetes feels like

CreateContainerConfigError vs. CreateContainerError

While these two errors may sound alike, they happen at different stages in the container lifecycle:

• CreateContainerConfigError: This happens when something is wrong with your Pod’s configuration. Think of it as a setup issue that stops the container from being created.

• CreateContainerError: This occurs later, during the actual creation of the container. The setup might be correct, but the container fails to start for other reasons.

CreateContainerError:

You can detect the error by running the kubectl get pods command:

CreateContainerError:

You can detect the error by running the kubectl get pods command:

NAME                 READY   STATUS                 RESTARTS   AGE
techops-examples     0/1     CreateContainerError   0          5m

When starting a container, Kubernetes goes through the initialization process, where it pulls the image, allocates resources, and mounts volumes. If any of these steps fail, Kubernetes triggers a CreateContainerError.

Common Causes for CreateContainerError:

Cause	Description
Incorrect Image	The image specified in the Pod manifest doesn’t exist, is unavailable, or lacks a command..
Resource Constraints	If the requested resources (CPU or memory) exceed the available capacity on the node.
Volume Mount Issues	The Pod is trying to mount a volume that doesn’t exist or is misconfigured.
Container Runtime Error	An issue with the container runtime (e.g., Docker, containerd) on the node.

How to Troubleshoot CreateContainerError:

1. Inspect Pod Details

Start by inspecting the Pod to get detailed insights into the container creation failure:

kubectl describe pod techops-examples

you can see that the container is in the “Waiting” state with the reason listed as CreateContainerError

Containers:
  techops-examples:
    Container ID:
    Image:          ubuntu:latest
    Image ID:
    State:          Waiting
      Reason:       CreateContainerError
    Ready:          False
    Restart Count:  0
    Resources:
      limits:
        memory: "4Gi"
        cpu: "2000m"
Volumes:
  data-volume:
    Type:      PersistentVolumeClaim (created from a PVC)
    Name:      data-pvc
    Optional:  false

2. Retrieve Logs

Use the following command to check the logs of the Pod’s container and find more details on why the container failed to start:

kubectl logs techops-examples

If the container has not yet been created, you may see an error indicating that there are no logs available.

3. Analyze Recent Pod Events

Use the kubectl get events command to view recent events related to the Pod and identify any specific reasons for the CreateContainerError.

kubectl get events --field-selector involvedObject.name=techops-examples

Example Output:

LAST SEEN   TYPE      REASON                OBJECT               MESSAGE
30s         Warning   FailedCreate          pod/techops-examples Failed to create container: CreateContainerError

4. Validate Resource Availability

Check if there are enough resources available (CPU and memory) on the node to run the container. Use:

kubectl top nodes

Fixing CreateContainerError:

1. Fix Image Issues

If the image specified is incorrect, ensure the correct image is pulled by providing a valid image name and tag:

containers:
- name: techops-examples
  image: nginx:1.21.3
  command: ["/bin/bash", "-c", "echo Application is up"]

If the error is caused by a missing command, add a valid entrypoint to the image.

2. Adjust Resource Requests

If the container is failing due to insufficient resources, adjust the resource requests and limits in the Pod configuration to fit the available resources on the node:

resources:
  requests:
    memory: "2Gi"
    cpu: "1000m"

3. Correct Volume Mounts

If the issue is with missing or misconfigured volumes, verify that the correct PersistentVolumeClaim (PVC) is available and referenced properly:

volumes:
- name: data-volume
  persistentVolumeClaim:
    claimName: data-pvc

in this example, ensure that the data-pvc exists in the namespace and that it is correctly configured.

4. Check Container Runtime

If there is a problem with the container runtime, review the kubelet logs on the node where the Pod is scheduled. Run the following command on the node:

sudo journalctl -u kubelet

Look for errors related to the container runtime and restart the kubelet or runtime service if needed.