As a part of a regular update, we are rolling out a change to the filesystem in the machines that all Docker executor jobs run on. Previously, jobs were running on hosts that used the AUFS filesystem driver backed by the ext4 filesystem. Now, the infrastructure has been updated to use the Overlay2 filesystem driver backed by the XFS filesystem. The AUFS filesystem driver is no longer supported by Docker, and replacing it with Overlay2 provides us with the opportunity to improve the performance of our Docker executor at the same time.
We have validated this change through extensive testing, and initial metrics show faster and more consistent job run times on the Docker executor for all customers. You won’t have to make any changes to take advantage of this performance improvement.
As of Monday February 1, this change has been rolled out for all Docker jobs on CircleCI. We don’t expect this change to cause any issue. However, if you do see any unexpected issues with Docker jobs in the next few days and believe the behavior could be related to this filesystem change, please create a new support ticket.
Feel free to ask any clarifying questions or add comments in this thread.