Kubernetes-ConfigMaps

:ID: c02e9bd0-e9fb-45d0-985a-4bdcbe62b8dc

ConfigMaps

A ConfigMap is a API object used to store non-confidential data in key-value pairs. Pods can consume ConfigMaps as environment variables, command-line arguments, or as configuration files in a volume.

apiVersion: v1
kind: ConfigMap
metadata:
  name: game-demo
  labels:
    app: game-demo
data:
  # property-like keys; each key maps to a simple value
  player_initial_lives: "3"
  ui_properties_file_name: "user-interface.properties"

  # file-like keys
  game.properties: |
    enemy.types=aliens,monsters
    player.maximum-lives=5    
  user-interface.properties: |
    color.good=purple
    color.bad=yellow
    allow.textmode=true

Creating a ConfigMap

From files

kubectl create configmap [name] --from-file=[filepath]

From environment variables

kubectl create configmap [name] --from-env-file=[filepath]

Using ConfigMaps in Pods

apiVersion: v1
kind: Pod
metadata:
  name: configmap-demo-pod
spec:
  containers:
    - name: demo
      image: alpine
      command: ["sleep", "3600"]
      env:
	# Define the environment variable
	- name: PLAYER_INITIAL_LIVES # Notice that the case is different here
				     # from the key name in the ConfigMap.
	  valueFrom:
	    configMapKeyRef:
	      name: game-demo           # The ConfigMap this value comes from.
	      key: player_initial_lives # The key to fetch.
	- name: UI_PROPERTIES_FILE_NAME
	  valueFrom:
	    configMapKeyRef:
	      name: game-demo
	      key: ui_properties_file_name
      volumeMounts:
      - name: config
	mountPath: "/config"
	readOnly: true
  volumes:
    # You set volumes at the Pod level, then mount them into containers inside that Pod
    - name: config
      configMap:
	# Provide the name of the ConfigMap you want to mount.
	name: game-demo
	# An array of keys from the ConfigMap to create as files
	items:
	- key: "game.properties"
	  path: "game.properties"
	- key: "user-interface.properties"
	  path: "user-interface.properties"