Configure Environment Variables in Kubernetes

 

What are Environment Variables?

Environment variables are key-value pairs which is used to pass the configuration values to an application without changing the application code.

Example:

Database URL

Username

Application Mode (dev, test, prod)

Why Use Environment Variables?

Instead of hardcoding values in the application code, We can pass them from Kubernetes.

DB_HOST=localhost

DB_HOST=mysql-service

This makes the application more flexible and easier to manage.

Example Deployment YAML

apiVersion: apps/v1

kind: Deployment

metadata:

  name: myapp

spec:

  replicas: 2

  selector:

    matchLabels:

      app: myapp

  template:

    metadata:

      labels:

        app: myapp

    spec:

      containers:

      - name: myapp

        image: nginx

        env:

        - name: APP_ENV

          value: "production"

        - name: COMPANY

          value: "HCL Pvt Ltd"

Understanding the Configuration

env:

- name: APP_ENV

  value: "production"

- name: DB_HOST

  value: "mysql-service"

Creates an environment variable.

APP_ENV=production

DB_HOST="HCL Pvt Ltd"

Verify Environment Variables

Find the Pod - kubectl get pods

Access the Pod - kubectl exec -it <pod-name> -- /bin/bash

View environment variables command:

env Or printenv

env APP_ENV Or printenv APP_ENV