[Fab-user] Chicken and Egg Issue with Roles/Environments

[Douglas Garstang]

All,

I'm trying to use fabric with both roles and environments (ie prod, stage, test etc). I started by following the example at http://yerb.net/blog/2014/03/03/multiple-environments-for-deployment-using-fabric/, which gave me the idea of using a task to set the environment.

However, I also need to populate the roledefs for that environment. My issue is that the environment is required to populate the roledefs. However, if I try and call the function to do that before the task that sets the environment, I don't know what the environment is yet. Conversely, if I try and populate the roledefs later, in the task that sets the environment, fabric complains "The following specified roles do not exist:".

This example below is where I attempt to set the roledefs after/during the task, and fabric complains with "The following specified roles do not exist:".

import os
from boto import ec2
from boto.exception import *
from fabric.api import *

def do_roledefs(environment):
    hosts = {}
    conn = ec2.connect_to_region('us-east-1',
            aws_access_key_id = os.environ['AWS_ACCESS_KEY'],
            aws_secret_access_key = os.environ['AWS_SECRET_KEY'])
    ec2_filter = { 'instance-state-name' : 'running', "tag:environment" : environment }
    reservations = conn.get_all_instances(filters=ec2_filter)
    instances = [i for r in reservations for i in r.instances]
    for i in instances:
        if 'role' in i.tags:
            if i.tags['role'] in hosts:
                hosts[i.tags['role']].append(i.private_ip_address)
            else:
                hosts[i.tags['role']] = [i.private_ip_address]
    env.roledefs = hosts

@task
def dev():
    stage_set('dev')

@task
def qa():
    stage_set('qa')

def stage_set(stage_name='test'):
    do_roledefs(stage_name)

Doug