A ruby script to update your AutoScaling Group by taking an image of an existing instance

UpdateASGroup.rb

#!/usr/bin/env ruby
# UpdateASGroup.rb
# Update AutoScaling Group with a new Image based from an running Instance
# (c) 2018 Keiran Smith <opensource_at_keiran.scot>
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
require 'aws-sdk'
require 'json'
require 'date'

# CONFIG
# PLEASE NOTE : You Must have AWS_ACCESS_KEY, AWS_SECRET_KEY,AWS_REGION env vars
# set for this script to work correctly.

image_prefix = "XXXXXX" # A prefix for the image name
group_name = "XXXXXX" # Name of AutoScaling Group

instance_id = "i-xxxxxx" # ID Of image to Instance
instance_type = "m3.large" # Instance Type

keypair = "Xxxxxx"         # String of Key Pair Name
security_groups = ["sg-xxxxxxxx", "sg-xxxxxxxx"] # Security Groups for Instance

# ENDCONFIG

ec2 = Aws::EC2::Resource.new
as = Aws::AutoScaling::Client.new

def rand_string
  (0..6).map{ ('a'..'z').to_a[rand(26)] }.join
end

puts "Newspaper Club AWS AutoScaling Updater"
puts "Updating AutoScaling Group #{group_name} using instance #{instance_id}"
instance = ec2.instance(instance_id)
puts ""
image_name = "#{image_prefix}-#{DateTime.now.strftime("%Y-%d-%m")}-#{rand_string}"
image_id = nil
image = instance.create_image({
  dry_run: false,
  name: image_name, # required
  description: "Auto Scaling Image",
  no_reboot: true,
})
image_id = image.id
puts "AMI ID: #{image_id}"

puts "Waiting for image to become ready"
while ec2.image(image_id).state != "available"
  printf "."
  # Sleep so we don't hit the rate limit
  sleep 5
end
puts ""
puts "Image is available Creating Auto Scaling Launch Config"

as.create_launch_configuration({
  launch_configuration_name: image_name,
  image_id: image_id,
  key_name: keypair,
  security_groups: security_groups,
  instance_type: instance_type,
  instance_monitoring: {
    enabled: true
  }
})

puts "Updating AutoScaling Group : #{group_name}"

as.update_auto_scaling_group({
  auto_scaling_group_name: group_name,
  launch_configuration_name: image_name
})

puts "Completed Update of #{group_name} with new AMI #{image_id}"