Container images get all the attention, but the thing a low-level runtime actually consumes is not an image. It is a bundle: a directory on disk containing an extracted root filesystem and a single JSON file. Understanding that file is the clearest possible explanation of what a container is.
There are hundreds of kubectl subcommands and you will use about fifteen. This is that fifteen,
with the flags that turn each one from "prints something" into "answers the question."
kind — Kubernetes IN Docker — runs each Kubernetes node as a Docker container. That sounds like a toy, but the nodes run real kubelets, a real control plane, and real container runtimes, which makes it the closest you can get to a production topology on a laptop. It is also what the Kubernetes project itself uses for conformance testing.
Every command below has been written to run as-is.
Kubernetes networking has a reputation for being impenetrable. It mostly is not — there are about five ideas, and the confusion comes from the fact that ClusterIPs are virtual addresses that no machine actually owns. Once that clicks, the rest follows.
"Kubernetes removed Docker support" caused a lot of confusion in 2021, and the confusion persists
because most people never had a reason to learn what sits underneath docker run. The stack is
layered, each layer has a specification, and once you see the boundaries the whole thing is
straightforward.