ImagePullBackOff Kubernetes error can be easily resolved once we find the root cause behind it. Read on to learn more. 

At Bobcares, we offer solutions for every query, big and small, as a part of our Server Management Services.

Let’s take a look at how our Support Team is ready to help customers with the ImagePullBackOff Kubernetes error.

What is the ImagePullBackOff Kubernetes error?

At times Kubernetes pods tend to run into issues while attempting to pull container images from a container registry. When this occurs, the pod switches to the ImagePullBackOff state.

In fact, when a Kubernetes cluster updates an already existing deployment or creates a new one, it has to pull an image. This action is done on each worker node by the kublet process. However, the images have to be accessible from all nodes in the cluster as per the scheduling request for this action to be successful.

So when a pod switches to the ImagePullBackOff state, it is not able to start since the Kubernetes cannot pull a container image. Furthermore, “BackOff” in ImagePullBackOff indicates that the Kubernetes will continue attempting to pull the image, albeit with an increasing delay.

Reasons Behind the ImagePullBackOff Kubernetes error

Here are the most common causes behind the ImagePullBackOff issue:

• The tag or image does not exist.
• There is a typo/spelling error in the tag or image name.
• The image registry needs authentication.
• The download limit on the registry has exceeded.

Let’s take a look at each of these reasons in detail.

When the image we are referencing does not exist, we are likely to come across the ImagePullBackOff Kubernetes error. In fact, this is one of the most seen causes. However, in some instances, the error occurs even if the image or tag exists. At this point, we have to ensure there are no typos in the image or tag name. Additionally, it is also a good idea to check whether the specific image tag still exists and has not been retired.

Furthermore, if we are pulling an image from a private image registry, we need the credentials to pull the image. This is done by creating a Secret with the appropriate credentials and then referencing it during pod specification. Additionally, we have to add the Secret in the corresponding namespace.

Moreover, we may need to create a Secret if we are pulling images from a publicly-accessible registry that is password protected. For instance Red Hat registry, GitHub Container Registry, and so on.

If we hit the maximum download limit on Docker Hub, we are likely to run into the ImagePullBackOff Kubernetes error. In this scenario, we have to either sign in or find another resource to get the image. Additionally, this may also occur if the registry needs SSL/TLS authentication.

If the above troubleshooting tips do not help, the error may be due to the network setup as well. Let us know in the comments which of our fixes helped you resolve the error.

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Conclusion

In a nutshell, our skilled Support Engineers at Bobcares demonstrated how to resolve the ImagePullBackOff Kubernetes error.