Creating a ConfigMap in Kubernetes

 

What is a ConfigMap?

A ConfigMap is a Kubernetes object which is used to store non-sensitive configuration data in the form of key-value pairs.

Examples:

Application environment

Server URL

Application port

Log level

Why we Use a ConfigMap?

Instead of hardcoding values in the Deployment, Store them in a ConfigMap and use them wherever it needed.

Create a ConfigMap

kubectl create configmap app-config --from-literal=APP_ENV=Production --from-literal=APP_PORT=8080

kubectl get configmap

kubectl describe configmap app-config

Use ConfigMap in a Deployment

apiVersion: apps/v1

kind: Deployment

metadata:

  name: nginx-config-demo

spec:

  replicas: 1

  selector:

    matchLabels:

      app: nginx-config-demo

  template:

    metadata:

      labels:

        app: nginx-config-demo

    spec:

      containers:

      - name: nginx

        image: nginx

        env:

        - name: APP_ENV

          valueFrom:

            configMapKeyRef:

              name: app-config

              key: APP_ENV

        - name: APP_PORT

          valueFrom:

            configMapKeyRef:

              name: app-config

              key: APP_PORT

Apply - kubectl apply -f deployment.yaml

Verify Inside the Pod

Get the Pod name - kubectl get pods

Login to the Pod - kubectl exec -it <pod-name> -- bash

Check values - printenv APP_ENV

Check values - printenv APP_PORT

ConfigMap YAML Example

apiVersion: v1

kind: ConfigMap

metadata:

  name: app-config

data:

  APP_ENV: Production

  APP_PORT: "8080"

  LOG_LEVEL: INFO

kubectl apply -f configmap.yaml