Connecting to a host listed in ~/.ssh/config when using Fabric

Question

I'm having trouble with Fabric not recognizing hosts that I have in ~/.ssh/config.

My fabfile.py is as follows:

from fabric.api import run, env

env.hosts = ['lulu']

def whoami():
    run('whoami')

Running $ fab whoami gives:

[lulu] run: whoami

Fatal error: Name lookup failed for lulu

The name lulu is in my ~/.ssh/config, like this:

Host lulu
     hostname 192.168.100.100
     port 2100
     IdentityFile ~/.ssh/lulu-key

My first thought to solving this is adding something like lulu.lulu to /etc/hosts (I'm on a Mac), but then I have to also pass in the identity file to Fabric - and I'd rather keep my authentication (i.e. ~/.ssh/config) separate from my deployment (i.e. fabfile.py).

As well, incidentally, if you try to connect to a host in the hosts file, fabric.contrib.projects.rsync_project doesn't seem to acknowledge 'ports' in the hosts.env (i.e. if you use hosts.env = [lulu:2100] a call to rsync_project seems to try connecting to lulu:21).

Is there a reason Fabric doesn't recognize this lulu name?

Answer 1

Since version 1.4.0, Fabric uses your ssh config (partly). However, you need to explicitly enable it, with

env.use_ssh_config = True

somewhere near the top of your fabfile. Once you do this, Fabric should read your ssh config (from ~/.ssh/config by default, or from env.ssh_config_path).

One warning: if you use a version older than 1.5.4, an abort will occur if env.use_ssh_config is set but there is no config file present. In that case, you can use a workaround like:

if env.ssh_config_path and os.path.isfile(os.path.expanduser(env.ssh_config_path)):
    env.use_ssh_config = True

Answer 2

Note that this also happens when the name is not in /etc/hosts. I had the same problem and had to add the host name to both that file and ~/.ssh/config.