instruction: Create a Dockerfile for configuration
output: ```dockerfile
  from v1.19, you can add an immutable field to a ConfigMap
  definition to create an immutable ConfigMap.ConfigMaps and PodsYou can write a Pod spec that refers to a ConfigMap and configures the container(s)
  in that Pod based on the data in the ConfigMap. The Pod and the ConfigMap must be in
  the same namespace.Note:The spec of a static Pod cannot refer to a ConfigMap
  or any other API objects.Here's an example ConfigMap that has some keys with single values,
  and other keys where the value looks like a fragment of a configuration
  format.apiVersion: v1
  kind: ConfigMap
  metadata:
   name: game-demo
  data:
   # property-like keys; each key maps to a simple value
   player_initial_lives: "3"
   ui_properties_file_name: "user-interface.properties"
  
   # file-like keys
   game.properties: |
   enemy.types=aliens,monsters
   player.maximum-lives=5
   user-interface.properties: |
   color.good=purple
   color.bad=yellow
   allow.textmode=true
  There are four different ways that you can use a ConfigMap to configure
  a container inside a Pod:Inside a container command and argsEnvironment variables for a containerAdd a file in read-only volume, for the application to readWrite code to run inside the Pod that uses the Kubernetes API to read a ConfigMapThese different methods lend themselves to different ways of modeling
  the data being consumed.
  For the first three methods, the
  kubelet uses the data
  ```