ConfigMaps

In this page, you can find an explanation how to create ConfigMaps and configure Pods using data, stored in ConfigMaps.

Table of contents

  1. What is the ConfigMap
  2. Create a ConfigMap
  3. Using ConfigMap

What is the ConfigMap

ConfigMap - is configuration options for separate objects. ConfigMap contains key/value pairs with the values ranging from short literals to full config files.

Create a ConfigMap

1) Use the kubectl create configmap command to create configmaps from directories, files, or literal values:

  • kubectl create configmap <map-name> <data-source>

where map-name is the name you want to assign to the ConfigMap and data-source is the directory, file, or literal value to draw the data from.

For example:

kubectl create configmap fortune-config --from-literal=sleep-interval=25

configmap/fortune-config created

Now you can inspect your configmap with command:

kubectl get configmap fortune-config -o yaml

apiVersion: v1
data:
  sleep-interval: "25"
kind: ConfigMap
metadata:
  creationTimestamp: "2020-02-24T16:10:50Z"
  name: fortune-config
  namespace: default
  resourceVersion: "2600128"
  selfLink: /api/v1/namespaces/default/configmaps/fortune-config
  uid: 04acfbfe-a208-43a1-a62e-7a9d8fb2f50e

2) Create ConfigMaps from directories

You can use kubectl create configmap to create a ConfigMap from multiple files in the same directory.

For exapmle:

Create the local directory:

mkdir -p configure-pod-container/configmap/

Download the sample files into configure-pod-container/configmap/ directory:

wget https://kubernetes.io/examples/configmap/game.properties -O configure-pod-container/configmap/game.properties

Create the configmap:

kubectl create configmap game-config --from-file=configure-pod-container/configmap/

configmap/game-config created

Now you can inspect your ConfigMap with command:

kubectl get configmap game-config -o yaml

apiVersion: v1
data:
  game.properties: |-
    enemies=aliens
    lives=3
    enemies.cheat=true
    enemies.cheat.level=noGoodRotten
    secret.code.passphrase=UUDDLRLRBABAS
    secret.code.allowed=true
    secret.code.lives=30
kind: ConfigMap
metadata:
  creationTimestamp: "2020-02-24T16:20:22Z"
  name: game-config
  namespace: default
  resourceVersion: "2601536"
  selfLink: /api/v1/namespaces/default/configmaps/game-config
  uid: a41a4fda-a464-4b5a-bbf3-1eb39af56775

3) Create ConfigMaps from files

You can use kubectl create configmap to create a ConfigMap from an individual file, or from multiple files.

For exapmle:

kubectl create configmap game-config-2 --from-file=configure-pod-container/configmap/game.properties

configmap/game-config-2 created

And use next command to inspect it:

kubectl get configmap game-config-2 -o yaml

apiVersion: v1
data:
  game.properties: |-
    enemies=aliens
    lives=3
    enemies.cheat=true
    enemies.cheat.level=noGoodRotten
    secret.code.passphrase=UUDDLRLRBABAS
    secret.code.allowed=true
    secret.code.lives=30
kind: ConfigMap
metadata:
  creationTimestamp: "2020-02-24T16:22:44Z"
  name: game-config-2
  namespace: default
  resourceVersion: "2601885"
  selfLink: /api/v1/namespaces/default/configmaps/game-config-2
  uid: f7a453c9-5939-4b60-9e21-e1c4cdc831b3

Using ConfigMap

1) Create yaml file and add the ConfigMap name under the volumes section of the Pod specification. This adds the ConfigMap data to the directory specified as volumeMounts.mountPath (in this case, /etc/config). The command section references the special.level item stored in the ConfigMap:

vi pod-volume.yaml

apiVersion: v1
kind: Pod
metadata:
  name: pod-volume
spec:
  containers:
    - name: test-container
      image: k8s.gcr.io/busybox
      command: [ "/bin/sh", "-c", "ls /etc/config/" ]
      volumeMounts:
      - name: config-volume
        mountPath: /etc/config
  volumes:
    - name: config-volume
      configMap:
        name: game-config
  restartPolicy: Never

2) Create a pod using kubectl create command:

kubectl create -f pod-volume.yaml

pod/pod-volume created

After pod was created, you can use kubectl logs to see result:

kubectl logs pod/pod-volume

game.properties