From manifests to a chart
Raw manifests for the shipping service, then a first chart, values, templates, helpers and configuration.
The shipping service as raw manifests
Deploy the shipping service with three plain Kubernetes manifests, then copy them for a second and third environment to see the problem a chart solves.
Your first chart
Build the shipping-service chart by hand from the three raw manifests, install it as a release, upgrade and roll it back, and find the release record Helm stores in the cluster.
Values and overrides
Design the chart's values interface, validate it with values.schema.json, and layer per-environment files and command-line flags in a predictable order.
Templates
How Helm renders a chart: Go template syntax, Sprig functions, built-in objects, whitespace control, if, with and range, and the functions that fail loudly or reach into the cluster.
Helpers and NOTES.txt
Move repeated names and labels into named templates in _helpers.tpl, apply the recommended Kubernetes labels, and print post-install guidance with NOTES.txt and .Files.
Configuration and secrets
Roll pods when a ConfigMap changes, supply API_TOKEN from values, an existing Secret or a generated one that survives upgrades, and compare the ways to keep secrets out of Git.