Ubuntu – Error `could not load host key` when trying to recreate SSH host keys

The solution I came up with is to set a password for the newly-booted nodes, and then manually insert SSH keys into each of them. To set a boot password for the ubuntu user, ensure that the following lines to /var/lib/cobbler/kickstarts/maas.preseed:

d-i    passwd/make-user boolean true
d-i    passwd/user-fullname ubuntu
d-i    passwd/username string ubuntu
d-i    passwd/user-password-crypted password <CRYPTED PASSWORD>

Once this is done, you can ssh ubuntu@ and use the password specified in the crypted password string (easiest way is to use one from an /etc/shadow file you already know) to log in. You can then insert your SSH public keys under ~ubuntu/.ssh/authorized_keys and ~root/.ssh/authorized keys.

Note that this is a workaround- once you ssh-keygen, MaaS should either be pulling the id_rsa.pub from your .ssh directory, or from the MaaS WebUI, where the user can specify a public key in his profile. No matter what I've tried, these keys aren't propagated, so I came up with the workaround.

A further cheat is to just add the .pub key to your MaaS node's .ssh/authorized_keys and then scp it to each of the nodes in the MaaS:

for i in `cobbler system list |grep -v default`; 
    do j=`cobbler system dumpvars --name "${i}" | grep hostname |grep -v duplicate |cut -f 2 -d \:`; 
    scp ~/.ssh/authorized_keys ubuntu@${j}:.ssh/authorized_keys;
done

This leaves you able to just repeatedly accept the SSH certificate errors and type the password in the crypted string to populate your entire MaaS with the SSH public key.

The command:

ssh-copy-id  username@host

As documented in the link above does not work from mac. Therefore, I logged in as root and of course, that is where the key was installed.

The answer seems to be: If You log in as the user, then cat the public key to the ~/.ssh/authorized_keys file.