Re: [atomic-devel] Thinking about CRI-O and Docker on Atomic Host

[Daniel Walsh <dwalsh redhat com>]

On 06/01/2017 01:19 PM, Antonio Murdaca wrote:

On Jun 1, 2017 17:58, "Colin Walters" <walters verbum org> wrote:

I've seen some interesting work on CRI-O for Kube/OpenShift.  But
I'm wondering about what people are thinking the future of
docker.service and /usr/bin/docker is (particularly for Atomic Host).

The particular intersection with AH is handling container storage;
AIUI right now you can't have CRI-O and Docker share the same
storage pool.

So...should a CRI-O installer `systemctl stop docker.service; systemctl mask docker.service`
and reuse the partition we've set up for /var/lib/docker?  Or do we
expect people to set up a separate partition?
(It feels like the answer is probably "both")

CRI-O can't actually use the Docker storage transparently. Either you use skopeo to copy images from Docker to cri-o storage or you start from scratch. 

CRI-O supports  "overlay" storage, (Formally overlay2, we have dropped the old overlay driver).  CRI-O storage is in /var/lib/containers/storage while docker is in /var/lib/docker.  They will not share the same storage, although all of the other container tools that we are building like skopeo and buildah will be able to share storage with CRI-O.  I am fine with moving to a single / with overlay by default for both docker and CRI-O.

Perhaps in the big picture for the single-node case we point people
at `oc cluster up` etc?  (Which itself should be a system container probably
to avoid the obvious bootstrapping problem?)