Mayur BN

08-Configure-ConfigMaps-in-Applications

Apr 05, 20242 min read

Configure ConfigMaps in Applications

In this section, we will take a look at configuring configmaps in applications

ConfigMaps

  • There are 2 phases involved in configuring ConfigMaps.
    • First, create the configMaps
    • Second, Inject then into the pod.
  • There are 2 ways of creating a configmap.

    • The Imperative way

      $ kubectl create configmap app-config --from-literal=APP_COLOR=blue --from-literal=APP_MODE=prod
$ kubectl create configmap app-config --from-file=app_config.properties (Another way)

      cmi

    • The Declarative way

      apiVersion: v1
kind: ConfigMap
metadata:
 name: app-config
data:
 APP_COLOR: blue
 APP_MODE: prod

      Create a config map definition file and run the 'kubectl create` command to deploy it.
$ kubectl create -f config-map.yaml

      cmd1

View ConfigMaps

  • To view configMaps

    $ kubectl get configmaps (or)
$ kubectl get cm

  • To describe configmaps

    $ kubectl describe configmaps

    cmv

ConfigMap in Pods

  • Inject configmap in pod

    apiVersion: v1
kind: Pod
metadata:
  name: simple-webapp-color
spec:
 containers:
 - name: simple-webapp-color
   image: simple-webapp-color
   ports:
   - containerPort: 8080
   envFrom:
   - configMapRef:
       name: app-config

    apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  APP_COLOR: blue
  APP_MODE: prod

    $ kubectl create -f pod-definition.yaml

    cmp

There are other ways to inject configuration variables into pod

  • You can inject it as a Single Environment Variable

  • You can inject it as a file in a Volume

    cmp1

K8s Reference Docs

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