[Fab-user] Feature request: Host reference

[Patrick J McNerthney]

Something I find very useful is not using the ssh host name as the name 
used in Fabric to identify which host(s) to operate on, but to instead 
use an assigned name.  By using something like the following dictionary:

env.host_configuration = {
       "production": {
           "host"     : "www.production.com",
           "user"     : "production",
           "keyfile" :  "~/.ssh/production.id_rsa",
           },
       "testing": {
           "host"     : "www.testing.com",
           "user"     : "testing",
           "keyfile" :  "~/.ssh/testing.id_rsa",
           },
       }

Then, a command might look something like this:

def staging():
   env.hosts = ['production']

def production():
   env.hosts = ['testing']

def deploy():
   run('foo')
   sudo('bar')

An obvious use case is allowing for different passwords or private keys 
per hosts.

What I have been doing with this kind of setup is performing some tasks 
that dynamically determine the ssh host name in my own commands.  For 
example, I start out with something like the following structure:

env.host_configuration = {
       "build": {
           "image"     : "ami-375abd5f",
           "type"         : "m1.small",
           "zone"        : "us-east-1b",
           "keyaws"   : "aws-ec2",
           "user"        : "build",
           "keyfile:     :  "~/.ssh/aws-ec2.id_rsa",
           "volume"   : "vol-8fa043e7",
           "device"    : "/dev/sdf",
           "mount"    : "/mnt/ebs",
           },
       }

I then have a "ec2_start" command that iterates through all selected 
hosts and starts an Amazon ec2 instance using the configuration 
information.  Once the instance is running, this "ec2_start" command 
then populates the host_configuration information with the host name 
that the instance got assigned.  So the rest of my fabfile.py might look 
something like this:

@hosts("build")
def build_it():
   ec2_start()
   run("the_build_command")

Just putting a thought out there.

Pat McNerthney
ClearPoint Metrics, Inc.