instruction: Create a Dockerfile for configuration
output: ```dockerfile
  from the output of ls -l;
  you must use ls -la to see them when listing directory contents.
  
  secret/dotfile-secret.yaml
  
  apiVersion: v1
  kind: Secret
  metadata:
   name: dotfile-secret
  data:
   .secret-file: dmFsdWUtMg0KDQo=
  ---
  apiVersion: v1
  kind: Pod
  metadata:
   name: secret-dotfiles-pod
  spec:
   volumes:
   - name: secret-volume
   secret:
   secretName: dotfile-secret
   containers:
   - name: dotfile-test-container
   image: registry.k8s.io/busybox
   command:
   - ls
   - "-l"
   - "/etc/secret-volume"
   volumeMounts:
   - name: secret-volume
   readOnly: true
   mountPath: "/etc/secret-volume"
  
  Use case: Secret visible to one container in a Pod
  Consider a program that needs to handle HTTP requests, do some complex business
  logic, and then sign some messages with an HMAC. Because it has complex
  application logic, there might be an unnoticed remote file reading exploit in
  the server, which could expose the private key to an attacker.
  This could be divided into two processes in two containers: a frontend container
  which handles user interaction and business logic, but which cannot see the
  private key; and a signer container that can see the private key, and responds
  to simple signing requests
  ```