deploy.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: example-deployment
spec:
  replicas: 1
  selector:
    matchLabels:
      app: example
  template:
    metadata:
      labels:
        app: example
    spec:
      initContainers:
      - name: init-nginx-config
        image: alpine:latest
        command: ['/bin/sh', '-c', 'apk add --no-cache openssl && echo "${USERNAME}:$(openssl passwd -apr1 ${PASSWORD})" > /etc/nginx/.htpasswd']
        env:
        - name: USERNAME
          valueFrom:
            secretKeyRef:
              name: example-secret
              key: username
        - name: PASSWORD
          valueFrom:
            secretKeyRef:
              name: example-secret
              key: <secret-key>
        volumeMounts:
        - name: config-volume
          mountPath: /etc/nginx/
      containers:
      - name: example-container
        image: nginx:latest
        ports:
        - containerPort: 80
        volumeMounts:
        - name: config-volume
          mountPath: /etc/nginx/
        - name: nginx-config-volume
          mountPath: /etc/nginx/nginx.conf
          subPath: nginx.conf
      volumes:
      - name: config-volume
        emptyDir: {}
      - name: <nginx-config-volume-name>
        configMap:
          name: nginx-config
          items:
            - key: nginx.conf
              path: nginx.conf