Capstone: Kubernetes, Everything

The finale of this series and of the whole From Scratch track. One ordinary command is followed through every stage already built, so six separate lessons collapse into a single program you can narrate start to finish.

Before you start. This series builds a small copy of Kubernetes: a program that keeps a fleet of machines running the programs you asked for, and restarts them when they die. Kubernetes calls one running copy of a program a pod. A container is the sealed box a program runs inside, so it can only see its own files and its own network, and a pod is one or more containers sharing that box. Six stages built the rest of it, one sentence each. You wrote down the state you wanted instead of a command to run, and running the same file twice changed nothing the second time (Kubernetes 01: Imperative to Declarative). A loop kept comparing what you’d asked for against what was real, forever, not just once (Kubernetes 02: The Reconcile Loop). Every change landed in one shared filing cabinet that anything could watch for updates (Kubernetes 03: Store and Watch). Asking for three pods made three pods appear, and stay at three (Kubernetes 04: Objects and Controllers). Each new pod got handed a machine to run on (Kubernetes 05: The Scheduler). That machine actually started it, and kept watching it (Kubernetes 06: The Kubelet). And one name out front let you reach any of them without knowing which one answered (Kubernetes 07: Services and Networking). This lesson adds nothing new. It runs all seven, once, in order.