How to save the Kubernetes pod stuck in a pending state? Read the article to find out more. Bobcares, as a part of our Server Management Services, offers solutions to every query that comes our way.

How To Save The Kubernetes Pod Stuck In A Pending State?

Kubernetes pods have different phases throughout their lifecycle. It will be in the pending state when it is created. Within seconds, it will be in the running state as soon as the pod is scheduled and the containers have started.

A pod’s life cycle stops when it cannot advance from the Pending to Running phase and is then retained until the issue preventing its development is fixed. Let’s look into some of the common causes behind the issues and the troubleshooting methods to solve them.

Kubernetes Pod Stuck In The Pending State Due To Scheduling Failure

A Kubernetes cluster tries to schedule a newly produced pod to execute on one of the nodes as soon as possible. This procedure is often incredibly quick, and the pod is promptly assigned to a node with sufficient resources to run it. But occasionally this scheduling won’t go as planned. The various causes include unscheduled nodes, taints and tolerations, and a lack of resources in any node to distribute the pod.

How to fix it? We can fix the issue by either reducing the requests in the pod spec or by increasing the capacity of the cluster by adding more nodes or increasing the size of every node.

Kubernetes Pod Stuck In Pending State Due To Dependency Issues

The kubelet tries to verify all dependencies with other Kubernetes components before the pod starts. The pod will remain in a pending state until the dependencies are met.

How to fix it? One can find out enough details in the Message column to identify the missing component. Typical causes include: There being no configuration map or secret, or the name given is incorrect. Because it hasn’t been released by another node yet, a volume cannot be mounted in the node. This occurs particularly when updating a statefulset because the volume installed must match the old pod. By trying to fix these issues, we can recover the pod stuck in a pending state due to dependency issues.

Kubernetes Pod Stuck In Pending State Due To Image Issues

The kubelet will attempt to start every container specified in the pod specification after the pod has been allocated to a node. It will attempt to download and run the image in order to accomplish that. The kubelet will send back ErrImagePull, then ImagePullBackOff, and keep attempting if something prevents the container runtime from pulling an image onto the node that Kubernetes has scheduled the Pod onto.

There are several reasons for this image-pulling issue, which include:

1. Wrong image name/tag: When we try to create a Pod which references an image name or tag that doesn’t exist, we’ll get ImagePullBackOff.

How to fix it? If we are very certain that the name is correct, perhaps the tag has been retired? Verify sure the image tag is still in use if you’re following an outdated tutorial or book that mentions it. Find out a suitable substitute tag to use if it doesn’t and use that one instead.

2. Repository issue: Most businesses that employ Kubernetes do so in cooperation with a personal container image registry. Generally speaking, businesses do not want to publish their internal, proprietary apps to Docker Hub. Therefore, if we need to pull an image from a private image registry, we must make sure to give Kubernetes the credentials it requires.

How to fix it? Create a Secret to accomplish this. This is also true if we’re pulling from a password-protected registry that is open to the public, such as the Red Hat registry, or even if we’re using private images on Google Container Registry, GitHub Container Registry, etc.

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Conclusion

The article provides some of the causes and solutions to fix the Kubernetes pod stuck in a pending state issue.