K8s resource: ConfigMap

What is ConfigMap?

ConfigMap in Kubernetes is a configuration resource that stores plain-text configuration such as insensitive environment variables app-specific configuration values.

Example ConfigMap YAML

apiVersion: v1
kind: ConfigMap
metadata:
  name: my-config
data:
  APP_ENV: production
  APP_DEBUG: "false"
  WELCOME_MESSAGE: "Hello from ConfigMap!"

How to use a ConfigMap in a pod

Method 1: Inject as environment variables

env:
  - name: APP_ENV
    valueFrom:
      configMapKeyRef:
        name: my-config
        key: APP_ENV

Method 2:

volumeMounts:
  - name: config-volume
    mountPath: /etc/config
volumes:
  - name: config-volume
    configMap:
      name: my-config

This will create files like /etc/config/APP_ENV and /etc/config/WELCOME_MESSAGE inside the pod.