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CRI-O Usage Transfer

This document outlines useful information for operations and development transfer as it relates to infrastructure that utilizes CRI-O.

Operational Transfer

Abstract

The crio daemon is intended to provide the CRI socket needed for Kubernetes to use for automating deployment, scaling, and management of containerized applications (See the document for configuring kubernetes to use CRI-O for more information). Therefore the crictl command line is a client that interfaces to the same gRPC socket as the kubernetes daemon would, for talking to the crio daemon. In many ways crictl is only as feature rich as the Kubernetes CRI requires. There are additional tools e.g. Podman and Buildah that provide a feature rich set of commands for all operational needs in a Kubernetes environment.

Please note that the full interoperability between CRI-O and Podman cannot be guaranteed at this time. For example, it is not possible to interact with CRI-O containers via Podman commands. To do this, please use tools which interferes with the CRI, like crictl.

System Tools

Many traditional tools will still be useful, such as pstree, nsenter and lsns. As well as some systemd helpers like systemd-cgls and systemd-cgtop are still just as applicable.

Equivalents

For many troubleshooting and information collection steps, there may be an existing pattern. Following provides equivalent with CRI-O tools for gathering information or jumping into containers, for operational use.

Existing Step CRI-O (and friends)
docker exec crictl exec
docker info podman info
docker inspect podman inspect
docker logs podman logs
docker ps crictl ps or runc list
docker stats podman stats

If you were already using steps like kubectl exec (or oc exec on OpenShift), they will continue to function the same way.

Development Transfer

There are other equivalents for these tools

Existing Step CRI-O (and friends)
docker attach podman exec ***
docker build buildah bud
docker cp podman mount ****
docker create podman create
docker diff podman diff
docker export podman export
docker history podman history
docker images podman images
docker kill podman kill
docker load podman load
docker login podman login
docker logout podman logout
docker pause podman pause
docker ps podman ps
docker pull podman pull
docker push podman push
docker rename podman rename
docker rm podman rm
docker rmi podman rmi
docker run podman run
docker save podman save
docker stop podman stop
docker tag podman tag
docker unpause podman unpause
docker version podman version
docker wait podman wait

*** Use podman exec to enter a container and podman logs to view the output of pid 1 of a container. **** Use mount to take advantage of the entire linux tool chain rather then just cp. Read here for more information.