ConfigMaps

Welcome to the module on ConfigMaps. Here you will learn key concepts and best practices to master this topic.

1. The Problem

Hardcoding configuration (DB URLs, API Keys) in container images is bad practice.

  • Rebuilds: You have to rebuild the image to change config.
  • Security: Secrets might leak.
  • Environment: Dev/Staging/Prod need different configs.

2. The Solution: ConfigMap

A key-value store for non-sensitive data. You can inject data into Pods as:

  1. Environment Variables: Good for simple flags.
  2. Files (Volume Mount): Good for nginx.conf or application.properties.

3. Interactive: Config Injection Visualizer

See how data flows from ConfigMap to Pod.

ConfigMap

DB_HOST=db.prod DEBUG=false
→

Pod (Env Vars)

DB_HOST=??? DEBUG=???

4. Code Example: Using ConfigMaps

ConfigMap
Pod (Env)
Pod (Volume)
apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  # Key-Value pairs
  DB_HOST: "postgres-svc"
  LOG_LEVEL: "info"

  # File content
  nginx.conf: |
    server {
      listen 80;
    }

apiVersion: v1
kind: Pod
metadata:
  name: env-demo
spec:
  containers:
  - name: app
  image: my-app
  envFrom:
  - configMapRef:
    name: app-config

apiVersion: v1
kind: Pod
metadata:
  name: volume-demo
spec:
  containers:
  - name: nginx
  image: nginx
  volumeMounts:
  - name: config-volume
    mountPath: /etc/nginx/conf.d
  volumes:
  - name: config-volume
  configMap:
    name: app-config