Container Tools

Linux containers

I was fortunate to attend Red Hat Summit earlier this year and managed to attend one of the sessions run by Dan Walsh of Red Hat. In the following talk he gives an overview of the evolution of containers and introduces some of the great work that the Open Container Initiative has brought us in terms of standardization (without which maybe containers would have had an RPM vs DEB type battle). No longer do we need to run Docker everywhere (no #bigfatdaeomons as Dan likes to say) – rather we can use smaller, bespoke tools according to our needs. For example, if I am building a container image I should have a lean tool that does just that.

Here is the talk:

Here are some useful links to get started:

  • Buildah – a tool that facilitates building Open Container Initiative (OCI) container images
  • CRI-O – Container runtime for Kubernetes
  • Skopeo – CLI for working with container images and image repositories
  • Podman – Manage container lifecycle
  • FAQ – Crictl vs Podman – FAQ – Crictl vs Podman

These are all available in the extras repo of your RHEL 7 distribution.  As always, it’s best to run the latest versions of RHEL – in this instance some of the tools are new so having RHEL 7.5 makes most sense.

# yum --enablerepo=rhel-7-server-extras-rpms search skopeo buildah podman oci-systemd-hook
Loaded plugins: enabled_repos_upload, langpacks, package_upload, product-id, search-
: disabled-repos, subscription-manager
=============================== N/S matched: skopeo ================================
skopeo.x86_64 : Inspect Docker images and repositories on registries
skopeo-containers.x86_64 : Configuration files for working with image signature
=============================== N/S matched: buildah ===============================
buildah.x86_64 : A command line tool used for creating OCI Images
=============================== N/S matched: podman ================================
podman.x86_64 : Manage Pods, Containers and Container Images
========================== N/S matched: oci-systemd-hook ===========================
oci-systemd-hook.x86_64 : OCI systemd hook for docker


OCI has opened up the container playing field. There’s no longer any need to rely on Docker, despite many people immediately associating the word ‘container’ with ‘Docker’. Most of the tools are compatible with the ‘dockerfile’ format so it’s easy to switch.