aws region timezone fact for puppet, useful for cron offsets when system time is UTC

region_tzinfo.rb

Facter.add('region_tzinfo') do
  ec2m = Facter.value(:ec2_metadata)
  # aws instances that have not been powercycled in 2+ years
  # will not have region in the metadata
  aws_zone = ec2m.dig('placement', 'availability-zone')
  iana_tz = case aws_zone
    when %r{^ap-southeast-1}
      'Asia/Singapore'
    when %r{^ap-southeast-2}
      'Australia/Sydney'
    when %r{^ap-southeast-3}
      'Asia/Jakarta'
    when %r{^ap-southeast-4}
      'Australia/Melbourne'
    when %r{^ca-central}
      'Canada/Central'
    when %r{^eu-west-1}
      'Europe/Dublin'
    when %r{^eu-west-2}
      'Europe/London'
    when %r{^eu-west-3}
      'Europe/Paris'
    when %r{^us-east}
      'America/New_York'
    when %r{^us-west}
      'America/Los_Angeles'
    else
      ENV['TZ'] || 'UTC'
    end
  
  old_tz = ENV['TZ']
  ENV['TZ'] = iana_tz
  data = {
    name: iana_tz,
    offset: Time.now.gmt_offset / 60 / 60,
    zone: Time.now.zone,
  }
  ENV['TZ'] = old_tz
  
  setcode do
    data
  end
end