CRI: Containerd by default

• First proposed: 2020-11-08
• Authors: Anders F Björklund (@afbjorklund)

Reviewer Priorities

Please review this proposal with the following priorities:

• Does this fit with minikube's principles?
• Are there other approaches to consider?
• Could the implementation be made simpler?
• Are there usability, reliability, or technical debt concerns?

Please leave the above text in your proposal as instructions to the reader.

Summary

Change default container runtime, from current "docker" to replacement "containerd".

Goals

• Change from docker to containerd as default
• Still allow fast-building images with minikube

Non-Goals

• Remove the docker support from minikube
• Change anything in the docker driver

Design Details

The containerd container runtime is already included, and is passing certification.

Unlike Docker, will need to include the CRI (runtime) and CNI (network) by default.

Use BuildKit as a complement to Containerd, for producing an image from Dockerfile.

Only run buildkitd on-demand (i.e. when building), default to running only containerd.

Alternatives Considered

Keep Docker as the default, and add the new CRI-Docker to replace the old dockershim.

Use CRI-O/Podman as default, which is a bigger change (since dockerd uses containerd).