Method: Cfer::Cfn::Client#tail

Defined in:
lib/cfer/cfn/client.rb

#tail(options = {}) ⇒ Object

Yields to the given block for each CloudFormation event that qualifies, given the specified options.

Parameters:

  • options (Hash) (defaults to: {}) —

    The options hash

Options Hash (options):

  • :number (Fixnum) —

    The maximum number of already-existing CloudFormation events to yield.

  • :follow (Boolean) —

    Set to true to wait until the stack enters a COMPLETE or FAILED state, yielding events as they occur.

  • :no_sleep (Boolean) —

    Don't pause between polling. This is used for tests, and shouldn't be when polling the AWS API.

  • :backoff (Fixnum) —

    The exponential backoff factor (default 1.5)

  • :backoff_max_wait (Fixnum) —

    The maximum amount of time that exponential backoff will wait before polling agian (default 15s)



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# File 'lib/cfer/cfn/client.rb', line 154

def tail(options = {})
  q = []
  event_id_highwater = nil
  counter = 0
  number = options[:number] || 0
  for_each_event name do |fetched_event|
    q.unshift fetched_event if counter < number
    counter = counter + 1
  end

  while q.size > 0
    event = q.shift
    yield event
    event_id_highwater = event.event_id
  end

  sleep_time = 1

  running = true
  if options[:follow]
    while running
      sleep_time = [sleep_time * (options[:backoff] || 1), options[:backoff_max_wait] || 15].min
      begin
        stack_status = describe_stacks(stack_name: name).stacks.first.stack_status
        running = running && (/.+_(COMPLETE|FAILED)$/.match(stack_status) == nil)

        yielding = true
        for_each_event name do |fetched_event|
          if event_id_highwater == fetched_event.event_id
            yielding = false
          end

          if yielding
            q.unshift fetched_event
          end
        end
      rescue Aws::CloudFormation::Errors::Throttling
        Cfer::LOGGER.debug "AWS SDK is being throttled..."
        # Keep going though.
      rescue Aws::CloudFormation::Errors::ValidationError
        running = false
      end

      while q.size > 0
        event = q.shift
        yield event
        event_id_highwater = event.event_id
        sleep_time = 1
      end

      sleep sleep_time if running unless options[:no_sleep]
    end
  end
end