# ConfigMaps — Kubernetes

Source: https://www.skillbyai.com/en/kubernetes/c-cm

> Non-secret settings outside the image.

## Same image, different config

A **ConfigMap** stores non-sensitive configuration as key-value pairs or whole files: log levels, feature flags, URLs of other services, configuration files. Keeping configuration out of images lets the **same image** run in development, staging and production. Note that values are strings (the flag "true" is quoted). Pods do not automatically restart when a ConfigMap changes; tools like Kustomize's config generators (which add a content hash to the name) trigger rollouts on changes.

## Separate config from images

ConfigMaps hold settings, Secrets hold sensitive values, and both reach pods as env vars or files.

![Three ideas: ConfigMaps, Secrets, consuming configuration.](assets/figures/kubernetes/section-4-map.svg) — Figure 4.1 — ConfigMaps, Secrets and consumption.

## Generating a ConfigMap from literals, run

I ran this with kubectl 1.37.0 using --dry-run=client (or kubectl kustomize), which generates manifests locally without a cluster; nothing was applied to a live cluster. Both values become strings in the data section; "true" is quoted to stay a string.

```bash
kubectl create configmap web-config --from-literal=LOG_LEVEL=info --from-literal=FEATURE_SEARCH=true --dry-run=client -o yaml
```

Output:

```
apiVersion: v1
data:
  FEATURE_SEARCH: "true"
  LOG_LEVEL: info
kind: ConfigMap
metadata:
  name: web-config
```

## Version config with the app

Generate ConfigMaps with a hash suffix so a config change rolls the Deployment and can be rolled back with it.

**Quiz:** Why keep configuration in ConfigMaps rather than in the image?

- [ ] It makes pods start faster
- [ ] Images cannot contain files
- [ ] ConfigMaps are encrypted
- [x] The same image can run in every environment with different settings

*Answer:* The same image can run in every environment with different settings. Build once, configure per environment.