AWS Lambda Ruby 2.7 EC2 Instances Stop

stop_ec2_instances.rb

require 'aws-sdk'
require 'json'

# Environments:
#   AWS_REGION = 'ap-northeast-1' as default
#   TARGET_INSTANCE_IDS = 'i-1234567890abcdef,i-2234567890abcdef' like comma-separated string
AWS_REGION = ENV['AWS_REGION'] || 'ap-northeast-1'

def lambda_handler(event:, context:)
    target_instance_ids = ENV['TARGET_INSTANCE_IDS'].split(',')
    result_messages = []

    client = Aws::EC2::Client.new(region: AWS_REGION)
    result_messages << "Describe Instances: #{target_instance_ids}"
    client.describe_instances(instance_ids: target_instance_ids).reservations.each do |reservation|
        next if reservation.instances.count < 1
        reservation.instances.each do |i|
            if i.state.name == 'running'
                result_messages << "#{i.instance_id} is running. stopping..."
                client.stop_instances(instance_ids: [i.instance_id])
                result_messages << "done"
            else
                result_messages << "#{i.instance_id} is not running"
            end
        end
    end
    result_messages << "stop_instances Done"
    client.wait_until(:instance_stopped, instance_ids: target_instance_ids)
    result_messages << "instance_stopped confirmed"

    { statusCode: 200, body: result_messages.join("\n") }
end