Container runtime alternatives to Docker

[lwilson]

Is your feature request related to a problem? Please describe.
Switch the container runtime from Docker/containerd to CRI-O

Describe the solution you'd like
https://kubernetes.io/docs/setup/production-environment/container-runtimes/#cri-o

Describe alternatives you've considered
We could stick with Docker, but would probably need to move off of the CentOS repos and onto CE.

Additional context
N/A

[lwilson]

@j0hnL should we go with CRI-O via CentOS, or use Fedora CoreOS (see #57)?

My position is that we install via CentOS, as we're still using the host OS for bare-metal HPC via Slurm.

It appears that there is already a CRI-O build in the CentOS7 repos (https://cbs.centos.org/koji/rpminfo?rpmID=167524).

[j0hnL]

it's worth moving away from Docker for lighter weight CRI-O environments. Let's give it a shot.

[j0hnL]

attempted to swap docker with CRI-O but led to failures and unable to start multi node k8s with our current setup using k8s v1.16.7 with cri-o v1.16

• coreDNS is not scheduled
• need to edit default config to change cgroup from systemd to cgroupfs

I would like to revisit CRI-O with newer version but let's call it for v1.16 and stick with docker on CentOS7 for now.

[lwilson]

@j0hnL I'm re-opening this. I think we should reconsider use of CRI-O with either runc or possibly crun for the container runtime. This would help us with both the Intel FPGA enablement (#84), and get us using a lighter weight container runtime.

[j0hnL]

CentOS8 has podman and buildah in default repos. We should explore using podman instead of docker.

[lwilson]

I changed the title of this issue to reflect that we are considering multiple options as Docker alternatives. @j0hnL I believe we need CRI-O on top of podman for it to work with Kubernetes, correct?

Also, since we are already considering moving to CentOS8 (#106) for OpenHPC (#37) this would be good to resolve.

[j0hnL]

We should consider the following limitations when running rootless containers:

https://github.com/containers/podman/blob/master/rootless.md

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[j0hnL]

the team is currently reviewing containerd and cri-o for 1.1 release

[lwilson]

We are currently discussion CRI-O vs containerd in discussion #332.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.