lib/cfer/cfn/client.rb in cfer-0.4.2 vs lib/cfer/cfn/client.rb in cfer-0.5.0.pre.rc1

@@ -155,10 +155,13 @@
 
     # Yields to the given block for each CloudFormation event that qualifies, given the specified options.
     # @param options [Hash] The options hash
     # @option options [Fixnum] :number The maximum number of already-existing CloudFormation events to yield.
     # @option options [Boolean] :follow Set to true to wait until the stack enters a `COMPLETE` or `FAILED` state, yielding events as they occur.
+    # @option options [Boolean] :no_sleep Don't pause between polling. This is used for tests, and shouldn't be when polling the AWS API.
+    # @option options [Fixnum] :backoff The exponential backoff factor (default 1.5)
+    # @option options [Fixnum] :backoff_max_wait The maximum amount of time that exponential backoff will wait before polling agian (default 15s)
     def tail(options = {})
       q = []
       event_id_highwater = nil
       counter = 0
       number = options[:number] || 0
@@ -171,33 +174,41 @@
         event = q.shift
         yield event
         event_id_highwater = event.event_id
       end
 
+      sleep_time = 1
+
       running = true
       if options[:follow]
         while running
-          stack_status = describe_stacks(stack_name: name).stacks.first.stack_status
-          running = running && (/.+_(COMPLETE|FAILED)$/.match(stack_status) == nil)
+          sleep_time = [sleep_time * (options[:backoff] || 1), options[:backoff_max_wait] || 15].min
+          begin
+            stack_status = describe_stacks(stack_name: name).stacks.first.stack_status
+            running = running && (/.+_(COMPLETE|FAILED)$/.match(stack_status) == nil)
 
-          yielding = true
-          for_each_event name do |fetched_event|
-            if event_id_highwater == fetched_event.event_id
-              yielding = false
-            end
+            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
+              if yielding
+                q.unshift fetched_event
+              end
             end
+          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 1 if running unless options[:no_sleep]
+          sleep sleep_time if running unless options[:no_sleep]
         end
       end
     end
 
     def stack_cache(stack_name)