One cargo plan, three ports

The middle of that board says it in one line: one versioned package, different values for dev, staging and prod. This lesson ships that package to three ports, loads a bad crate at one of them, and takes it back.

Before you start. The Harbor Master (pods, deployments, services) gave you the harbour’s ledger: you write a short text file saying what you want running (a YAML file, which is just lines of name: value), and the cluster keeps making it true. Pods, ReplicaSets & Deployments (the ownership chain) showed how a Deployment swaps in a new version one copy at a time, keeping the old copies running until the new ones are ready. And Infrastructure as Code & GitOps showed that Helm can fill blanks in a file before the cluster ever sees it; this lesson takes that file on to the cluster and keeps a record of every time it lands.

The idea in 30 seconds

A Helm chart is a set of Kubernetes files with blanks in them, plus a file of default values; each place it runs gets a small file that fills the blanks.
Installing a chart makes a release, and every install, upgrade or rollback of it adds a numbered revision that Helm stores inside the cluster.
A Helm rollback never erases the bad revision; it adds a new revision that copies an old one.
Kustomize has no blanks: a complete base, plus one overlay per environment listing only what differs, all in plain Kubernetes YAML.
Kustomize keeps no history in the cluster, so undoing a change means reverting the commit in git and applying again.
Use a chart to hand a package to others; use a base and overlays for YAML you own where environments differ a little.

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