# Values Files and Overrides — Helm

Source: https://www.skillbyai.com/en/helm/u-values

> Override chart defaults with values files and --set, and predict which value wins.

## Layers of configuration

Every chart ships a `values.yaml` with defaults. You override them when installing or upgrading, and Helm merges the layers in a fixed order, later layers winning: the chart's own `values.yaml`, then a parent chart's values for its subcharts, then each file passed with **`-f` / `--values`** in the order given, then **`--set`**, `--set-string` and `--set-file` flags. Maps are merged key by key, but **lists are replaced entirely**, not merged. `--set` uses a compact path syntax (`image.tag=2.7.1`, `ingress.hosts[0].host=shop.example.com`) that becomes awkward for anything complex, so keep real configuration in version-controlled values files and use `--set` mainly for values computed in a pipeline, such as an image tag. `helm get values RELEASE` shows the values you supplied; add `--all` to see the fully computed result.

## Values precedence

Defaults sit at the bottom; each layer above overrides the ones below it.

![Four stacked horizontal layers increasing in colour intensity from bottom to top, with an arrow pointing upward to show which wins.](assets/figures/helm/section-2-map.svg) — Figure 2.1 — Chart defaults, values files in order, then --set flags.

## Layered values for production

`values-prod.yaml` overrides `values.yaml`, and the pipeline sets only the image tag.

```yaml
# values.yaml (chart defaults)
replicaCount: 1
image:
  repository: registry.example.com/shop-api
  tag: ""            # defaults to the chart's appVersion in templates
resources:
  requests: { cpu: 100m, memory: 128Mi }

# values-prod.yaml (environment overrides)
replicaCount: 3
resources:
  requests: { cpu: 500m, memory: 512Mi }
  limits:   { memory: 1Gi }

# command used by the pipeline
# helm upgrade --install shop-api ./charts/shop-api -n shop \
#   -f values-prod.yaml --set image.tag=2.7.1
```

## Lists do not merge

If the defaults contain `tolerations: [a, b]` and your file sets `tolerations: [c]`, the result is just `[c]`. Copy every list entry you want to keep into the override.

**Quiz:** A value is set in values.yaml, in values-prod.yaml passed with -f, and with --set. Which wins?

- [ ] values.yaml
- [ ] values-prod.yaml
- [x] The --set value
- [ ] Whichever is alphabetically first

*Answer:* The --set value. --set overrides values files, which override the chart defaults.