Using an SSH keyfile with Fabric

Question

How do you configure fabric to connect to remote hosts using SSH keyfiles (for example, Amazon EC2 instances)?

Answer 1

As stated above, Fabric will support .ssh/config file settings after a fashion, but using a pem file for ec2 seems to be problematic. IOW a properly setup .ssh/config file will work from the command line via 'ssh servername' and fail to work with 'fab sometask' when env.host=['servername'].

This was overcome by specifying the env.key_filename='keyfile' in my fabfile.py and duplicating the IdentityFile entry already in my .ssh/config.

This could be either Fabric or paramiko, which in my case was Fabric 1.5.3 and Paramiko 1.9.0.

Answer 2

Finding a simple fabfile with a working example of SSH keyfile usage isn't easy for some reason. I wrote a blog post about it (with a matching gist).

Basically, the usage goes something like this:

from fabric.api import *

env.hosts = ['host.name.com']
env.user = 'user'
env.key_filename = '/path/to/keyfile.pem'

def local_uname():
    local('uname -a')

def remote_uname():
    run('uname -a')

The important part is setting the env.key_filename environment variable, so that the Paramiko configuration can look for it when connecting.