How to debug “ImagePullBackOff”?

Question

All of a sudden, I cannot deploy some images which could be deployed before. I got the following pod status:

[root@webdev2 origin]# oc get pods 
NAME                 


        

Answer 1

On GKE, if the pod is dead, it's best to check for the events. It will show in more detail what the error is about.

In my case, I had :

Failed to pull image "gcr.io/project/imagename@sha256:c8e91af54fc17faa1c49e2a05def5cbabf8f0a67fc558eb6cbca138061a8400a":
 rpc error: code = Unknown desc = error pulling image configuration: unknown blob

It turned out the image was damaged somehow. After repushing it and deploying with the new hash, it worked again.