instruction: Create a Dockerfile for configuration
output: ```dockerfile
  from a Pod section.Using a SecretSecrets can be mounted as data volumes or exposed as
  environment variables
  to be used by a container in a Pod. Secrets can also be used by other parts of the
  system, without being directly exposed to the Pod. For example, Secrets can hold
  credentials that other parts of the system should use to interact with external
  systems on your behalf.Secret volume sources are validated to ensure that the specified object
  reference actually points to an object of type Secret. Therefore, a Secret
  needs to be created before any Pods that depend on it.If the Secret cannot be fetched (perhaps because it does not exist, or
  due to a temporary lack of connection to the API server) the kubelet
  periodically retries running that Pod. The kubelet also reports an Event
  for that Pod, including details of the problem fetching the Secret.Optional SecretsWhen you reference a Secret in a Pod, you can mark the Secret as optional,
  such as in the following example. If an optional Secret doesn't exist,
  Kubernetes ignores it.secret/optional-secret.yaml
  apiVersion: v1
  kind: Pod
  metadata:
   name: mypod
  spec:
   containers:
   - name: mypod
   image: redis
   volumeMounts:
   - name: foo
   mountPath: "/etc/foo"
   readOnly: true
   volumes:
   - name: foo
   secret:
   secretName: mysecret
   optional: trueBy default, Secrets are required. None of a Pod's containers will start until
  all non-optional Secrets are available.If a Pod references a specific key in a non-optional Secret and that Secret
  does exist, but is missing the named key, the Pod fails during startup.<h3 id=using-secrets-as-files-
  ```