There is currently a Google Compute Engine Maintenance in London.
We are observing multiple nodes at a time from different clusters being restarted with the following log:
…pe-west2-xx-xxx-xxxx-xxxxx-xxxxxxx-xxxxx system@google.com Instance terminated during Compute Engine maintenance.
We have an escalated support case with Google to determine the length of the maintenance.
Depending on the size of your cluster, most restarts will not cause a dropout due to the redundancy in place, however if multiple nodes in your cluster restart at the same time this could cause a dropout for a few minutes.
We apologies for the inconvenience caused, We did not have any notice of this maintenance and will follow up.
