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Comment by mynameisash | Hacker News Reader

I know that K8s isn't Docker, but discussing learning the former, does anyone have a suggestion for learning the latter? I know what Docker is and have even used it for a production service, but I definitely don't feel like I've learned it "properly". I vaguely recall reading some of the Docker documentation and was underwhelmed with its ability to onboard newbies.

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I'm a big fan of Julia Evans' zines. They're short and to-the-point and are often excellent jumping off points.

This one seems highly relevant: https://wizardzines.com/zines/containers/

This was also posted on HN a couple weeks ago: https://earthly.dev/blog/chroot/

Docker's recent licensing changes seem to make it not as popular anymore (>10M revenue every developer needs a license for docker desktop). Kubernetes even deprecated docker as a container runtime (https://kubernetes.io/blog/2020/12/02/dont-panic-kubernetes-...).

That deprecation was because the Docker shim (compatibility layer) was expensive to maintain. You can still use containerd, which is Docker’s runtime, as a Kubernetes runtime.

This framing (Docker is losing popularity, even k8s is deprecating it) is misleading. The article you linked to clears that up immediately out of the gate (emphasis added):

> You do not need to panic. It’s not as dramatic as it sounds.

> TL;DR Docker as an underlying runtime is being deprecated in favor of runtimes that use the Container Runtime Interface (CRI) created for Kubernetes. Docker-produced images will continue to work in your cluster with all runtimes, as they always have.

> If you’re an end-user of Kubernetes, not a whole lot will be changing for you. This doesn’t mean the death of Docker, and it doesn’t mean you can’t, or shouldn’t, use Docker as a development tool anymore. Docker is still a useful tool for building containers, and the images that result from running docker build can still run in your Kubernetes cluster.

I learned it by first building a homelab cluster and spinning up simple services with DNS on it. Then I did the same on a cloud provider. Digital Ocean has some great guides and starter kits for how to do it on their platform.

https://devopswithdocker.com/

I suggest reframing the question to, “how do I learn how to build container images?” Docker as a container runtime is dying fast and being replaced, so no need to learn the runtime.

The lasting contribution of Docker is the Dockerfile, learning that and the alternative ways to build an image is sufficient in 2022.

Learning Dockerfile is most of the work of learning Docker, and the docs and tutorials for Docker are far more thorough and useful at this stage than the docs for podman or whatever else.

There's no harm in learning Docker even if it gets replaced completely in the next 10 years, because there's enough industry inertia behind it that any replacement will be highly backwards compatible.

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