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ConfigMaps

Store non-sensitive application configuration data separately from your container images using ConfigMaps.

Introduction

ConfigMaps store configuration data that your applications need to function, such as environment URLs, feature flags, and application settings. Unlike Secrets, ConfigMaps are for non-sensitive data that can be viewed openly.

Why use ConfigMaps:

  • Keep configuration separate from container images
  • Change settings without rebuilding applications
  • Share configuration across multiple containers
  • Environment-specific settings (dev vs prod)

ConfigMaps vs Secrets:

  • ConfigMaps: Non-sensitive configuration data (API URLs, feature flags, log levels) - managed via GitOps
  • Secrets: Sensitive data (passwords, API keys, certificates)

Creating ConfigMaps

Using YAML Manifests

Since ConfigMaps contain non-sensitive data, manage them via GitOps in your code repository:

apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
  namespace: my-app
data:
  app-env: "production"
  log-level: "info"
  api-base-url: "https://api.example.com"
  feature-x-enabled: "true"

Environment-Specific ConfigMaps

Create different ConfigMaps for each environment:

# Development environment
apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
  namespace: my-app-dev
data:
  log-level: "debug"
  api-base-url: "https://api.dev.example.com"
---
# Production environment
apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
  namespace: my-app-prod
data:
  log-level: "warn"
  api-base-url: "https://api.example.com"

Using ConfigMaps

Environment Variables

Most common way to consume configuration:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
spec:
  template:
    spec:
      containers:
      - name: my-app
        image: my-app:latest
        env:
        # Reference specific config keys
        - name: APP_ENV
          valueFrom:
            configMapKeyRef:
              name: app-config
              key: app-env
        - name: LOG_LEVEL
          valueFrom:
            configMapKeyRef:
              name: app-config
              key: log-level
        # Or use envFrom to load all keys
        envFrom:
        - configMapRef:
            name: app-config

Volume Mounts

For configuration files:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx
spec:
  template:
    spec:
      containers:
      - name: nginx
        image: nginxinc/nginx-unprivileged:latest
        volumeMounts:
        - name: config
          mountPath: /etc/nginx/nginx.conf
          subPath: nginx.conf
          readOnly: true
      volumes:
      - name: config
        configMap:
          name: nginx-config

Complete Example: Application with ConfigMaps

# configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
  namespace: my-app
data:
  app-env: "production"
  log-level: "info"
  api-base-url: "https://api.example.com"
  feature-x-enabled: "true"
---
# deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
spec:
  replicas: 1
  selector:
    matchLabels:
      app: my-app
  template:
    metadata:
      labels:
        app: my-app
    spec:
      containers:
      - name: my-app
        image: my-app:latest
        env:
        - name: APP_ENV
          valueFrom:
            configMapKeyRef:
              name: app-config
              key: app-env
        - name: LOG_LEVEL
          valueFrom:
            configMapKeyRef:
              name: app-config
              key: log-level
        - name: API_BASE_URL
          valueFrom:
            configMapKeyRef:
              name: app-config
              key: api-base-url

Best Practices

Configuration Guidelines

  • Never put secrets in ConfigMaps - use Secrets for sensitive data
  • Use environment-specific values - different ConfigMaps per environment (dev, staging, prod)

Operational Considerations

  • ConfigMap updates require pod restarts - restart the deployment to pick up new values
  • Use namespace isolation - ConfigMaps are namespace-scoped

Next Steps

Now that you understand ConfigMaps: