Here’s a trick to get a host key automatically registered by ssh, particularly when used by git as part of a build pipeline…
The main trick is to use the ssh -o StrictHostKeyChecking=no option:
ssh -o StrictHostKeyChecking=no user@server
If the relevant known_hosts file does not contain the server or even does not
exist, it will create the file and add the server key.
This is particularly useful when using ssh as part of git command via the
GIT_SSH_COMMAND env var:
GIT_SSH_COMMAND=ssh -o StrictHostKeyChecking=no -i keyfile user@server
When this is run as part of a pipeline on a build server, and therefore is
running under a service user, it can be particularly difficult to locate the
known_hosts file.
For instance if running under LocalSystem, the file could be something like
C:\Windows\SysWOW64\config\systemprofile\.ssh\known_hosts.
Errors relating to this may show something like Host key verification failed
but also maybe something as obscure as read_passphrase: can't open /dev/tty: No such device or address
(even though the key file has no passphrase!).
Once the known_hosts file has been update, the -o StrictHostKeyChecking=no
will no longer be needed and can be removed again.
Thanks
Info found on this StackExchange response