Values Files and Overrides

values.yaml is the chart's interface: every key is a setting users may change, so keep it short, commented and grouped by component. BookNest's defaults reproduce the production manifests:

helm/booknest/values.yaml: BookNest's defaultsYAML

api:
  image: { repository: localhost:33500/booknest-api, tag: "1.4" }
  replicas: 2                  # used only when autoscaling is off
  autoscaling: { enabled: false, minReplicas: 2, maxReplicas: 6, cpu: 70 }
  resources: { requests: { cpu: 50m, memory: 64Mi }, limits: { memory: 256Mi } }
web:
  image: { repository: localhost:33500/booknest-web, tag: "1.3" }
  replicas: 2
db:
  host: ""                     # empty: the bundled postgres subchart, <release>-postgres
  secret: ""                   # empty: <release>-db, generated on first install
  name: booknest
  user: booknest
migrations:
  image: localhost:33500/postgres:18
postgres:                      # values for the postgres subchart
  enabled: true
  storageClass: booknest-data
  size: 1Gi

An environment supplies only its differences, in a file passed with -f or single keys with --set. Later sources win, merging key by key rather than replacing whole maps:

helm/staging.yaml: what staging changesYAML

api:
  image: { tag: "1.3" }
  autoscaling: { enabled: true, minReplicas: 1, maxReplicas: 2 }
web: { replicas: 1 }

Rendering with a values file and a --set on topShell

helm template demo helm/booknest -f helm/staging.yaml --set web.replicas=3 \
  | yq -N '[.kind, .metadata.name, .spec.replicas, .spec.minReplicas, .spec.maxReplicas,
      .spec.template.spec.containers[0].image] | map(select(. != null) | to_string)
      | join(" ")' \
  | grep -E '^(Deployment|HorizontalPodAutoscaler)'

Output

Deployment demo-api localhost:33500/booknest-api:1.3
Deployment demo-web 3 localhost:33500/booknest-web:1.3
HorizontalPodAutoscaler demo-api 1 2

The API took staging's tag and an autoscaler; the front end took --set's 3 over staging's 1. Precedence runs, lowest first: the chart's values.yaml, a parent chart's values for a subchart, each -f file, then --set. Keep lasting settings in files under version control (Helm Upgrades shows why), and add a values.schema.json to have Helm 29,435 validate every value.

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