A set of tasks for use with Fabric and EC2.

Installation

Now available on PyPi at http://pypi.python.org/pypi/cloth. Installation is therefore as simple as:

pip install cloth

Configuration

Export your EC2 credntials as environment variables.

export AWS_EC2_REGION=eu-west-1
export AWS_ACCESS_KEY_ID=<your-access-key>
export AWS_SECRET_ACCESS_KEY=<your-secret-key>

Usages

To use just import some or all of the tasks into your fabric file. Or create a blank fabfile.py with the following contents.

#! /usr/bin/env python
from cloth.tasks import *

This will give you a good few commands.

⚡ fab -l

Available commands:

  all         All nodes
  exclude     Exclude specific nodes based on a regular expression.
  execute     Execute a command on a remote host with options for grouping/counting results.
  list        List EC2 name and public and private ip address
  nodes       Select nodes based on a regular expression

Of most interest should be the 'all' and 'nodes' tasks. These allow you to load EC2 instances for further command running.

⚡ fab all list

The above should list all of your EC2 instances including the name and public and private ip addresses.

⚡ fab nodes:"^production.*" list

The above should list all of your EC2 instances that start with 'production'. This takes a regex as the argument so you can get whatever instances you like.

Execute

A convenience function called execute is provided to easily perform remote executions:

⚡ fab all execute:uptime

As an example of running a command on a set of EC2 instances try the above. This should show the uptime and load averages for all your EC2 instances. Use -P as well to have that happen in parallel.

This command also includes group and count options to aid in summarization:

fab all execute:"uname -r",group=true

Shows:

{ '3.10.82-12.101.amzn1.x86_64': [ 'host2',
                                   'host8'],
{ '3.10.40-50.136.amzn1.x86_64': [ 'host1',
                                   'host3',
                                   'host6',
                                   'host9']}

Use count like so:

fab all execute:"uname -r",count=true

Shows:

{ '3.10.82-12.101.amzn1.x86_64': 2,
{ '3.10.40-50.136.amzn1.x86_64': 4}

Opinionated Tasks

I generally use a convention for the names of my EC2 machines, in particular:

<platform>-<role>-<unique-identifier>

The production and preview tasks simple filter for those with a platform value of production or preview. More interesting is that roles are being set based on the second part of the name. For instance if I have a set of instances called:

• production-backend-1
• production-backend-2
• production-backend-3
• production-proxy
• production-database

I could write a task like so:

@task
@roles('backend')
def passenger():
    "Show details about passenger performance"
    sudo('passenger-memory-stats')
    sudo('passenger-status')

The run that task with:

⚡ fab all passenger

That task would only be run on the three backend instances.