instruction: Create a Dockerfile for configuration
output: ```dockerfile
  from the password WordPress
  uses to access MySQL. Store this password securely, such as in a password
  manager. You need it to log into WordPress after
  rotating the secret.Go ahead and write a blog post or two and install a WordPress plugin or
  theme to verify that WordPress is fully operational and its state is saved
  across service restarts.Do not clean up any services or secrets if you intend to proceed to the next
  example, which demonstrates how to rotate the MySQL root password.Example: Rotate a secretThis example builds upon the previous one. In this scenario, you create a new
  secret with a new MySQL password, update the mysql and wordpress services to
  use it, then remove the old secret.
  NoteChanging the password on a MySQL database involves running extra
  queries or commands, as opposed to just changing a single environment variable
  or a file, since the image only sets the MySQL password if the database doesnât
  already exist, and MySQL stores the password within a MySQL database by default.
  Rotating passwords or other secrets may involve additional steps outside of
  Docker.Create the new password and store it as a secret named mysql_password_v2.
  
  $ openssl rand -base64 20 | docker secret create mysql_password_v2 -
  Update the MySQL service to give it access to both the old and new secrets.
  Remember that you cannot update or rename a secret, but you can revoke a
  secret and grant access to it using a new target filename.
  
  $ docker service update \
   --secret-rm mysql_password mysql
  
  $ docker service update \
   --secret-add source=mysql_password,target=old_mysql_password \
   --secret-add source=mysql_password_v2,target=mysql_password \
   mysql
  Updating a service causes it to restart, and when the MySQL service restarts
  the second time, it has access to the old secret under
  /run/secrets/old_mysql_password and the new secret under
  /run/secrets/mysql_password.Even though the MySQL service has access to both the old and new secrets
  now, the MySQL password for the WordPress user has not yet been changed.
  NoteThis example does not rotate the MySQL root password.Now, change the MySQL password for the wordpress user using the
  mysqladmin CLI. This command reads the old and new password
  ```