Nginx with ConfigMap Volume Mount

Custom Nginx Config via ConfigMap

Rather than building a custom Docker image for every Nginx configuration change, you can store the config in a Kubernetes ConfigMap and mount it into the container. This separates configuration from the container image, following the 12-factor app methodology.

Key Configuration

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-custom
  labels:
    app: "nginx-custom"
spec:
  replicas: 2
  template:
    spec:
      containers:
        - name: nginx
          image: nginx:1.25-alpine
          ports:
            - name: http
              containerPort: 80
          volumeMounts:
            - name: nginx-config
              mountPath: /etc/nginx/conf.d
              readOnly: true
          resources:
            requests:
              cpu: "50m"
              memory: "64Mi"
            limits:
              cpu: "200m"
              memory: "128Mi"
      volumes:
        - name: nginx-config
          configMap:
            name: nginx-conf

Creating the ConfigMap

Before deploying, create the ConfigMap with your Nginx configuration:

kubectl create configmap nginx-conf \
  --from-file=default.conf=./my-nginx.conf

Or define it in YAML:

apiVersion: v1
kind: ConfigMap
metadata:
  name: nginx-conf
data:
  default.conf: |
    server {
      listen 80;
      location / {
        proxy_pass http://backend:3000;
      }
    }

Mount Details

The volume mount replaces the entire /etc/nginx/conf.d/ directory with the contents of the ConfigMap. Each key in the ConfigMap becomes a file in the mounted directory. Using readOnly: true prevents the container from accidentally modifying the mounted config.

Hot Reloads

When you update the ConfigMap, Kubernetes eventually propagates the change to the mounted volume (this can take up to 1 minute by default). However, Nginx does not automatically reload its configuration. You need either a sidecar that watches for file changes and sends SIGHUP to Nginx, or a rolling restart of the deployment.