I've followed the recommendations I could find to prevent this from happening.  I am using Vagrant, but once the boxes are spun, I'd like to do things with the `ansible` command sometimes.

    $ grep host_key /etc/ansible/ansible.cfg                                                                                                               
    host_key_checking = False
    
    $ grep kafka01 ./inventory
    kafka01 ansible_host=127.0.0.1 ansible_port=2231 ansible_user='vagrant' ansible_ssh_private_key_file='/home/me/project/project/.vagrant/machines/kafka01/virtualbox/private_key' ansible_ssh_common_args='-o StrictHostKeyChecking=no'
    
    $ export ANSIBLE_HOST_KEY_CHECKING=False
    $ ansible kafka01 -m ping -i ./inventory                                                                                                               
    
     [WARNING]: Unhandled error in Python interpreter discovery for host kafka01: Failed to connect to the host via ssh: @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@  @    WARNING:
    REMOTE HOST IDENTIFICATION HAS CHANGED!     @  @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@  IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!  Someone could be eavesdropping on
    you right now (man-in-the-middle attack)!  It is also possible that a host key has just been changed.  The fingerprint for the ECDSA key sent by the remote host is
    SHA256:jn5ClU5g566Gsvobf8Xc45DJnIiAllN+RJkg35Nf9KE.  Please contact your system administrator.  Add correct host key in /home/me/.ssh/known_hosts to get rid of this message.  Offending ECDSA key
    in /home/me/.ssh/known_hosts:19    remove with:    ssh-keygen -f "/home/me/.ssh/known_hosts" -R "[127.0.0.1]:2231"  ECDSA host key for [127.0.0.1]:2231 has changed and you have requested strict
    checking.  Host key verification failed.
    
    kafka01 | UNREACHABLE! => {
    .....

 What's going on here?