Re-implement --tail flag

stacker/__init__.py

@@ -4,12 +4,13 @@
 
 
 def plan(description=None, action=None,
+         tail=None,
          stacks=None, stack_names=None,
          reverse=False):
     """A simple helper that builds a graph based plan from a set of stacks."""
 
     steps = [
-        Step(stack, fn=action)
+        Step(stack, fn=action, watch_func=tail)
         for stack in stacks]
 
     return build_plan(

stacker/actions/build.py

@@ -319,6 +319,7 @@ def _generate_plan(self, tail=False):
         return plan(
             description="Create/Update stacks",
             action=self._launch_stack,
+            tail=self.provider.tail_stack if tail else None,
             stacks=self.context.get_stacks(),
             stack_names=self.context.stack_names)
 

stacker/actions/destroy.py

@@ -36,6 +36,7 @@ def _generate_plan(self, tail=False):
         return plan(
             description="Destroy stacks",
             action=self._destroy_stack,
+            tail=self.provider.tail_stack if tail else None,
             stacks=self.context.get_stacks(),
             stack_names=self.context.stack_names,
             reverse=True)

stacker/plan2.py

@@ -2,6 +2,7 @@
 import logging
 import time
 import uuid
+import multiprocessing
 
 from .actions.base import stack_template_key_name
 from .exceptions import (
@@ -33,11 +34,12 @@ class Step(object):
             with this step
     """
 
-    def __init__(self, stack, fn=None):
+    def __init__(self, stack, fn=None, watch_func=None):
         self.stack = stack
         self.status = PENDING
         self.last_updated = time.time()
         self.fn = fn
+        self.watch_func = watch_func
 
     def __repr__(self):
         return "<stacker.plan.Step:%s>" % (self.stack.fqn,)
@@ -49,9 +51,22 @@ def run(self):
 
         log_status(self.name, self.status)
 
-        while not self.done:
-            status = self.fn(self.stack, status=self.status)
-            self.set_status(status)
+        watcher = None
+        if self.watch_func:
+            watcher = multiprocessing.Process(
+                target=self.watch_func,
+                args=(self.stack,)
+            )
+            watcher.start()
+
+        try:
+            while not self.done:
+                status = self.fn(self.stack, status=self.status)
+                self.set_status(status)
+        finally:
+            if watcher and watcher.is_alive():
+                watcher.terminate()
+                watcher.join()
         return self.ok
 
     @property