Calling SSH command from Jenkins

Because when having numerous slave machine it could be hard to anticipate on which of them build will be executed, rather then explicitly calling ssh I highly suggest using existing Jenkins plug-ins for SSH executing a remote commands:

• Publish Over SSH - execute SSH commands or transfer files over SCP/SFTP.
• SSH - execute SSH commands.

The default 'jenkins' user is the system user running your jenkins instance (master or slave). Depending on your installation this user can have been generated either by the install scripts (deb/rpm/pkg etc), or manually by your administrator. It may or may not be called 'jenkins'.

To find out under what user your jenkins instance is running, open the http://$JENKINS_SERVER/systemInfo, available from your Manage Jenkins menu.

There you will find your user.home and user.name. E.g. in my case on a Mac OS X master:

user.home   /Users/Shared/Jenkins/Home/user.name   jenkins

Once you have that information you will need to log onto that jenkins server as the user running jenkins and ssh into those remote servers to accept the ssh fingerprints.

An alternative (that I've never tried) would be to use a custom jenkins job to accept those fingerprints by for example running the following command in a SSH build task:

ssh -o "StrictHostKeyChecking no" your_remote_server

This last tip is of course completely unacceptable from a pure security point of view :)

So one might make a "job" which writes the host keys as a constant, like:

echo "....." > ~/.ssh/known_hosts

just fill the dots from ssh-keyscan -t rsa {ip}, after you verify it.