Is OverlayFS (overlay and overlay2) supported for use with the docker container runtime?

Solution Verified - Updated

Environment

  • Red Hat Enterprise Linux 7
  • Red Hat Enterprise Linux Atomic Host
  • docker

Issue

  • Can overlayfs or overlayfs2 be used when using the docker container runtime?
  • Can I use overlay or overlay2 as a backing filesystem for containers?

Resolution

  • RHEL / RHEL Atomic Host 7.3

    • OverlayFS (overlay)
      • Supported for docker containers on 7.3 provided the restrictions noted in the Release Notes for RHEL 7.3 are followed.
        • Host has SELinux enabled, but the docker daemon must have SELinux disabled
    • OverlayFS 2 (overlay2)
      • Technology Preview on 7.3
      • Host has SELinux enabled, but the docker daemon must have SELinux disabled

  • RHEL / RHEL Atomic Host 7.4

    • OverlayFS (overlay and overlay2)
      • Support for docker containers on 7.4 provided the restrictions noted in the Release Notes for RHEL 7.4 are followed:
        • Only XFS is supported for use as a lower layer file system
        • XFS file systems must be created with the -n ftype=1 option enabled for use as an overlay
        • OverlayFS provides a restricted set of the POSIX standards. Test your application thoroughly before deploying it with OverlayFS
        • In order to make the yum and rpm utilities work properly inside the container, the user should be using the yum-plugin-ovl packages
      • Support for SELinux enabled in docker daemon
        • Requires RHEL 7.4 kernel, 3.10.0-693.el7 or newer
        • Requires docker-1.12.6-48.git0fdc778.el7 or newer

  • RHEL / RHEL Atomic Host 7.5 and newer

    • For new installations the default docker storage driver has changed from devicemapper to overlay2
    • Existing installations that upgrade will not change
    • Same caveats/restrictions for OverlayFS continue to apply

Diagnostic Steps

See the Red Hat Enterprise Linux Atomic Host Managing Containers Guide, Chapter 1. Managing Storage with Docker-formatted Containers - Section 1.6. Using the Overlay Graph Driver for instructions on configuring the docker daemon to use the overlay2 storage backend.

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