List servers in all EC2 regions

list.rb

require 'fog'

AWS = Fog::Compute.new(:provider => 'AWS')

REGIONS = AWS.describe_regions.body["regionInfo"].map {|region| region["regionName"]}

COMPUTE = {}
REGIONS.each do |region|
    COMPUTE.merge!(region => Fog::Compute.new({:provider => 'AWS', :region=>region}))
end

COMPUTE.each_pair do |region,connection|
  puts "***#{region}***"
  availability_zones = connection.describe_availability_zones.body["availabilityZoneInfo"].map{|zone| zone["zoneName"]}
  availability_zones.each do |zone|
    puts "**#{zone}**"
    puts connection.servers.select{|server| server.availability_zone == zone}.map{|server| server.tags["Name"]}
  end
end