Overriding ConfigMap variables in Kubernetes

Apr 24, 2019

Much like default values.yaml files for Helm, you can utilize ConfigMaps in Kubernetes for much the same capability. Our developers have started to do this to make it easier when managing Deployment objects across different environments.

Give a ConfigMap:

apiVersion: v1
data:
  allowed: '"true"'
  enemies: aliens
  lives: "3"
kind: ConfigMap
metadata:
  name: engage
  namespace: default

and a Deployment:

    spec:
      containers:
      - env:
        - name: enemies
          value: badguy
        envFrom:
        - configMapRef:
            name: engage

Taking a look inside the container:

engage-6c8c65588b-m8pww# env | grep enemies
enemies=badguy