ConfigMap and Secret

Write a ConfigMap and Secret for app configuration.

ConfigMap and Secret

Settings are split in two: non-secret ones go in a ConfigMap (under version control), secret ones in a Secret (by command, outside the repository). The API's connection address uses the service names:

# 40-ayar.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: api-ayar
  namespace: magaza
data:
  DB_HOST: db
  DB_PORT: "5432"
  DB_NAME: magaza
  LOG_LEVEL: info

When settings change

When the ConfigMap is updated, the API pods using it as environment variables keep seeing the old value. To apply it, the deployment is restarted; since it's renewed gradually, there's no downtime:

kubectl apply -f k8s/40-ayar.yaml
kubectl rollout restart deployment/api -n magaza
kubectl rollout status deployment/api -n magaza
kubectl exec -n magaza deploy/api -- printenv LOG_LEVEL

Exercise The project's ConfigMap

Write a ConfigMap YAML: name api-ayar, namespace magaza; under data, DB_HOST: db, DB_PORT: "5432", LOG_LEVEL: info.

Show example solution

apiVersion: v1
kind: ConfigMap
metadata:
  name: api-ayar
  namespace: magaza
data:
  DB_HOST: db
  DB_PORT: "5432"
  LOG_LEVEL: info

Test yourself

Why is the DB_PORT value written in quotes?
- ConfigMap values must be strings; 5432 is read as a number in YAML
- Because the port is secret
- Quotes aren't required, just habit
- For base64
Show answer

ConfigMap values must be strings; 5432 is read as a number in YAML — An unquoted number makes the ConfigMap get rejected.

Print a single environment variable in the container.

kubectl exec -n magaza deploy/api -- ____ LOG_LEVEL

Show answer

kubectl exec -n magaza deploy/api -- printenv LOG_LEVEL

Match.

ConfigMap

In the repo, not secret
Secret

By command, secret
DB_HOST: db

Service name
rollout restart

Apply the new setting

Next lesson: Putting it together - multi-tier

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