Change:
klog.V(2).Infof("Attach operation successful: volume %q attached to node %q.", volumeSource.DataDiskURI, nodeName) } else { klog.V(2).Infof("Attach volume %q to instance %q failed with %v", volumeSource.DataDiskURI, nodeName, err) <del> return "", fmt.Errorf("Attach volume %q to instance %q failed with %v", volumeSource.DiskName, nodeName, err) </del> <ins> return "", err </ins> } }

Discussion:
<!-- Please use this template while reporting a bug and provide as much info as possible. Not doing so may result in your bug not being addressed in a timely manner. Thanks! If the matter is security related, please disclose it privately via --What happened: Pods with PVs could not be moved from one node to another. According to the controller-manager logs, K8s tried to detach to Azure disks from the same node. One of the detach operation waited for this lock (). While it waited for the lock, the controller-manager pod was restarted (for whatever reason, not related to this bug, lets assume an operator restarted the pod). After the restart, K8s only tried to attach the disk to the new node but is not trying to detach it first. What you expected to happen: After a restart of the controller-manager, it should continue unfinished detach operations How to reproduce it (as minimally and precisely as possible): 2 Pods with PVs running on one node Move both pods to another node restart the controller-manager shortly after the move Anything else we need to know?: Environment: Kubernetes version (use ): 1.15.1 Cloud provider or hardware configuration: Azure OS (e.g: ): Kernel (e.g. ): Install tools: Network plugin and version (if this is a network-related bug): Others:
/sig azure
/sig cloud-provider
/area provider/azure that's expected behavior, k8s controller won't continue detach volume if controller manager restarted, user needs to detach that disk volume manually.
Could you please elaborate why this behaviour is expected. I would assume that the controller manager tries to reach the desired state after a restart? Then it would need to detect that the volume is still attached to the wrong node and should try to detach it once more, before it continuing to attach the (still attached) volume? This leads to many ... Why is it required to resolve this situation by manual interaction?
I can't imagine that "manual intervention" is "desired behaviour" (yes, you wrote "expected", but that doesn't matter, if you make no proposal, how to improve this). If this isn't fixed, we can't use Azure, period. We can't have clusters that need to be babysitted / you cannot expect people running workloads on Azure clusters and babysit them and manually fixing what should/can fix itself.

Level-triggered behaviour and resilience is what made Kubernetes so successful... please bring that also to Azure's KCM/CCM.
do you know why controller manager is restarted, it's not a common scenario, we cannot guarantee disk attach/detach functionality works if controller manager restarted at that time.
related to
I think there can be many reasons why the controller-manager is restarted during running detach or attach operations e. g. the hosting machine turn into error state, if you run the controller-manager in k8s -vertical pod autoscaling,... etc. I understand you can't guarantee that attach/detach works when the controller-manager is restarted, but I don't understand why the controller-manager can't recover the situation autonomously after a restart. After restart it tries to attach the volume of the rescheduled pod and this does not work because the volume is still attached to another machine. This is indicated by a error from the arm and the controller-manager could react to it properly, right?
This is an upstream issue, and there is a discussion in , let's check whether we can fix it in cloud provider driver in that thread. Thanks.
I will try to fix this issue in azure disk driver, thanks all for the discussion. details: /assign
Thank you very much It means a lot to us, that there are no manual operations. I wonder how you guys deal with it in AKS, since Azure uses the same controllers, right? Anyway, it helps tremendously, that the clusters are self-healing.
AKS use same kube-controller-manager, while it won't be restarted easily.
OK, but how? I understand that AKS only supports 100 nodes. So, I guess you have some upper limit and just hope, nobody stresses it, because if this happens, you it either restarts or you need to scale it up and then it gets restarted as well. Also, regular maintenance, low-level as well as Kubernetes updates, all must impact it. Considering the probably thousands over thousands of clusters (I don't know, but I expect you run many), any such problem, even if unlikely by itself, must be in your interest to fix, simply because the number of clusters increases the likelihood that it happens, I would think. Anyway, thank you for making this change
Yes, that's reasonable, I will try to fix it as my top priority.