ELBAS (Elastic Load Balancer & AutoScaling)

ELBAS was written to ease the deployment of Rails applications to AWS AutoScale groups. ELBAS will:

• Deploy your code to each running instance connected to a given AutoScale group
• After deployment, create an AMI from one of the running instances
• Attach the AMI with the new code to a new AWS Launch Configuration
• Update your AutoScale group to use the new launch configuration
• Delete any old AMIs created by ELBAS
• Delete any old launch configurations created by ELBAS

This ensures that your current and future servers will be running the newly deployed code.

Installation

gem 'elbas'

Add this statement to your Capfile:

require 'elbas/capistrano'

Configuration

Below are the Capistrano configuration options with their defaults:

set :aws_access_key_id,     ENV['AWS_ACCESS_KEY_ID']
set :aws_secret_access_key, ENV['AWS_SECRET_ACCESS_KEY']
set :aws_region,            ENV['AWS_REGION']

set :aws_no_reboot_on_create_ami, true
set :aws_autoscale_instance_size, 'm1.small'

set :aws_launch_configuration_detailed_instance_monitoring, true
set :aws_launch_configuration_associate_public_ip, true

set :aws_iam_instance_profile, 'profile_name'
set :aws_key_pair,             'key_name'
set :aws_base_instance_name,   'server_123'

Usage

Instead of using Capistrano's server method, use autoscale instead in deploy/production.rb (or whichever environment you're deploying to). Provide the name of your AutoScale group instead of a hostname:

autoscale 'production', user: 'apps', roles: [:app, :web, :db]

That's it! Run cap production deploy. ELBAS will print the following log statements during your deployment:

"ELBAS: Adding server: ec2-XX-XX-XX-XXX.compute-1.amazonaws.com"
"ELBAS: Creating EC2 AMI from i-123abcd"
"ELBAS: Created AMI: ami-123456"
"ELBAS: Creating an EC2 Launch Configuration for AMI: ami-123456"
"ELBAS: Created Launch Configuration: elbas-lc-ENVIRONMENT-UNIX_TIMESTAMP"
"ELBAS: Attaching Launch Configuration to AutoScale Group"
"ELBAS: Deleting old launch configuration: elbas-lc-production-123456"
"ELBAS: Deleting old AMI: ami-999999"
"ELBAS: Deleting snapshot: snap-123456"

To run just the rake task, which is called after the deployment above:

cap production elbas:scale