AWS SDK for Ruby
Developer Guide

Starting an Amazon EC2 Instance

The following example starts the instance i-123abc in the us-west-2 region.

require 'aws-sdk-ec2' # v2: require 'aws-sdk' ec2 = 'us-west-2') i = ec2.instance('i-123abc') if i.exists? case i.state.code when 0 # pending puts "#{id} is pending, so it will be running in a bit" when 16 # started puts "#{id} is already started" when 48 # terminated puts "#{id} is terminated, so you cannot start it" else i.start end end