Unlimited option max_resources_per_stack

Since biggest issue for memory problems is nested stack max
resources validation, this patch creates option to remove limit
which skips whole validation whatsoever.

Change-Id: I7c851fcad2d4a41b2f9df42244862b04304812b0
Partial-Bug: #1455589

heat/common/config.py

@@ -115,7 +115,8 @@ engine_opts = [
                        ' delegated to heat when creating a stack.')),
     cfg.IntOpt('max_resources_per_stack',
                default=1000,
-               help=_('Maximum resources allowed per top-level stack.')),
+               help=_('Maximum resources allowed per top-level stack. '
+                      '-1 stands for unlimited.')),
     cfg.IntOpt('max_stacks_per_tenant',
                default=100,
                help=_('Maximum number of stacks any one tenant may have'

heat/engine/resources/stack_resource.py

@@ -224,6 +224,8 @@ class StackResource(resource.Resource):
         return parsed_template
 
     def _validate_nested_resources(self, templ):
+        if cfg.CONF.max_resources_per_stack == -1:
+            return
         root_stack_id = self.stack.root_stack_id()
         total_resources = (len(templ[templ.RESOURCES]) +
                            self.stack.total_resources(root_stack_id))

heat/engine/service.py

@@ -570,8 +570,11 @@ class EngineService(service.Service):
                         " Please delete some stacks.") % tenant_limit
             raise exception.RequestLimitExceeded(message=message)
 
+        max_resources = cfg.CONF.max_resources_per_stack
+        if max_resources == -1:
+            return
         num_resources = len(parsed_template[parsed_template.RESOURCES])
-        if num_resources > cfg.CONF.max_resources_per_stack:
+        if num_resources > max_resources:
             message = exception.StackResourceLimitExceeded.msg_fmt
             raise exception.RequestLimitExceeded(message=message)
 
@@ -753,7 +756,8 @@ class EngineService(service.Service):
                 current_stack.env,
                 args.get(rpc_api.PARAM_CLEAR_PARAMETERS, []))
         tmpl = templatem.Template(template, files=files, env=env)
-        if len(tmpl[tmpl.RESOURCES]) > cfg.CONF.max_resources_per_stack:
+        max_resources = cfg.CONF.max_resources_per_stack
+        if max_resources != -1 and len(tmpl[tmpl.RESOURCES]) > max_resources:
             raise exception.RequestLimitExceeded(
                 message=exception.StackResourceLimitExceeded.msg_fmt)
         stack_name = current_stack.name

heat/tests/engine/test_stack_create.py

@@ -21,6 +21,7 @@ from heat.engine.clients.os import nova
 from heat.engine import environment
 from heat.engine import properties
 from heat.engine import resource as res
+from heat.engine.resources.aws.ec2 import instance as instances
 from heat.engine import service
 from heat.engine import stack
 from heat.engine import template as templatem
@@ -339,3 +340,13 @@ class StackCreateTest(common.HeatTestCase):
                                ctx, stk)
         self.assertEqual('Missing required credential: X-Auth-Key',
                          six.text_type(ex))
+
+    @mock.patch.object(instances.Instance, 'validate')
+    @mock.patch.object(stack.Stack, 'total_resources')
+    def test_stack_create_max_unlimited(self, total_res_mock, validate_mock):
+        total_res_mock.return_value = 9999
+        validate_mock.return_value = None
+        cfg.CONF.set_override('max_resources_per_stack', -1)
+        stack_name = 'service_create_test_max_unlimited'
+        stack = tools.get_stack(stack_name, self.ctx)
+        self.man.create_stack(self.ctx, stack_name, stack.t.t, {}, None, {})