Add the droplet hostkey to the executing server:

doex ssh.hostkey <droplet_id_or_name_or_tag>

You can provide the droplet ID, reference it by name, or by tag (if you add the --tag option).

For example:

doex ssh.hostkey my_app

This is useful after you have first created a droplet so that you can then SSH into that server without any human intervention asking if you want to continue:

The authenticity of host '99.98.97.97 (99.98.97.97)' can't be established.
ECDSA key fingerprint is SHA256:ABCDEFHIK/def.
Are you sure you want to continue connecting (yes/no)?

If you have a specific config file, mix help doex.config then add it as an environment variable:

DOEX_CONFIG=/tmp/my.doex doex ssh.hostkey my_app