如何确定fabfile中的结构角色以将特定文件发送到主机

Question

I have an environment that sort of looks like this:

env.roledefs = {
    'cisco-collectors': ['hosta', 'hostb', 'hostc'],
    'brocade-collectors': ['hosta', 'hostd']
}

and I have some specific files that need to be sent to hosts in specific roles:

files = {
    'cisco-collectors': ['/path/to/filea', '/path/to/fileb'],
    'brocade-collectors': ['/path/to/filec', '/path/to/filed']
}

How do I write my sendFiles() function so that when a role is specified on the command line, or even with the @roles() decorator I'll be able to get the proper file list?

This question shows a way to determine if the host belongs to a role, but I need to get the role currently being executed so I know which file list to send.

Ideally it would look like this:

@roles('cisco-collectors', 'brocade-collectors')    
def sendFiles():
  for file in files[env.current_role]:
    put(file)

Answer 1

env.host_string.role contains the current role in the newest fabric source (unreleased).

The commit

Answer 2

In my tests, I don't think you can reliably get the current role in 1.5. See Pavel's answer about how this will change. While this may seem inconvenient, I think the reason is that Fabric combines the list of hosts, so role doesn't carry over.

There is a workaround if you don't need to use the role functionality, though. You can create a task which alters the hosts list. This will only work for one role though!

from fabric.api import task, local, env

@task
def role1():
    env.current_role = 'role1'
    env.hosts.extend(['example.com'])

@task
def role2():
    env.current_role = 'role2'
    env.hosts.extend(['test.example.com'])

@task
def test():
    print env.current_role
    print env.hosts

If you now run fab role1 test you will see:

[localhost] Executing task 'test'
role1
['localhost', 'example.com']
[example.com] Executing task 'test'
role1
['localhost', 'example.com']

Not exactly what you were after ... but may help lead you to what will work.