functional/test_autoscaling.py

#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.

import copy
import json
import logging

from testtools import matchers

from heat_integrationtests.common import test


LOG = logging.getLogger(__name__)


class AutoscalingGroupTest(test.HeatIntegrationTest):

    template = '''
{
  "AWSTemplateFormatVersion" : "2010-09-09",
  "Description" : "Template to create multiple instances.",
  "Parameters" : {"size": {"Type": "String", "Default": "1"},
                  "AZ": {"Type": "String", "Default": "nova"},
                  "image": {"Type": "String"},
                  "flavor": {"Type": "String"}},
  "Resources": {
    "JobServerGroup": {
      "Type" : "AWS::AutoScaling::AutoScalingGroup",
      "Properties" : {
        "AvailabilityZones" : [{"Ref": "AZ"}],
        "LaunchConfigurationName" : { "Ref" : "JobServerConfig" },
        "MinSize" : {"Ref": "size"},
        "MaxSize" : "20"
      }
    },

    "JobServerConfig" : {
      "Type" : "AWS::AutoScaling::LaunchConfiguration",
      "Metadata": {"foo": "bar"},
      "Properties": {
        "ImageId"           : {"Ref": "image"},
        "InstanceType"      : {"Ref": "flavor"},
        "SecurityGroups"    : [ "sg-1" ],
        "UserData"          : "jsconfig data"
      }
    }
  },
  "Outputs": {
    "InstanceList": {"Value": {
      "Fn::GetAtt": ["JobServerGroup", "InstanceList"]}},
    "JobServerConfigRef": {"Value": {
      "Ref": "JobServerConfig"}}
  }
}
'''

    instance_template = '''
heat_template_version: 2013-05-23
parameters:
  ImageId: {type: string}
  InstanceType: {type: string}
  SecurityGroups: {type: comma_delimited_list}
  UserData: {type: string}
  Tags: {type: comma_delimited_list}

resources:
  random1:
    type: OS::Heat::RandomString
    properties:
      salt: {get_param: ImageId}
outputs:
  PublicIp: {value: {get_attr: [random1, value]}}
  AvailabilityZone: {value: 'not-used11'}
  PrivateDnsName: {value: 'not-used12'}
  PublicDnsName: {value: 'not-used13'}
  PrivateIp: {value: 'not-used14'}
'''

    # This is designed to fail.
    bad_instance_template = '''
heat_template_version: 2013-05-23
parameters:
  ImageId: {type: string}
  InstanceType: {type: string}
  SecurityGroups: {type: comma_delimited_list}
  UserData: {type: string}
  Tags: {type: comma_delimited_list}

resources:
  random1:
    type: OS::Heat::RandomString
    depends_on: waiter
  ready_poster:
    type: AWS::CloudFormation::WaitConditionHandle
  waiter:
    type: AWS::CloudFormation::WaitCondition
    properties:
      Handle: {Ref: ready_poster}
      Timeout: 1
outputs:
  PublicIp:
    value: {get_attr: [random1, value]}
'''

    def setUp(self):
        super(AutoscalingGroupTest, self).setUp()
        self.client = self.orchestration_client
        if not self.conf.image_ref:
            raise self.skipException("No image configured to test")
        if not self.conf.minimal_image_ref:
            raise self.skipException("No minimal image configured to test")
        if not self.conf.instance_type:
            raise self.skipException("No flavor configured to test")

    def assert_instance_count(self, stack, expected_count):
        inst_list = self._stack_output(stack, 'InstanceList')
        self.assertEqual(expected_count, len(inst_list.split(',')))

    def _assert_instance_state(self, nested_identifier,
                               num_complete, num_failed):
        for res in self.client.resources.list(nested_identifier):
            if 'COMPLETE' in res.resource_status:
                num_complete = num_complete - 1
            elif 'FAILED' in res.resource_status:
                num_failed = num_failed - 1
        self.assertEqual(0, num_failed)
        self.assertEqual(0, num_complete)


class AutoscalingGroupBasicTest(AutoscalingGroupTest):

    def test_basic_create_works(self):
        """Make sure the working case is good.

        Note this combines test_override_aws_ec2_instance into this test as
        well, which is:
        If AWS::EC2::Instance is overridden, AutoScalingGroup will
        automatically use that overridden resource type.
        """

        files = {'provider.yaml': self.instance_template}
        env = {'resource_registry': {'AWS::EC2::Instance': 'provider.yaml'},
               'parameters': {'size': 4,
                              'image': self.conf.image_ref,
                              'flavor': self.conf.instance_type}}
        stack_identifier = self.stack_create(template=self.template,
                                             files=files, environment=env)
        initial_resources = {
            'JobServerConfig': 'AWS::AutoScaling::LaunchConfiguration',
            'JobServerGroup': 'AWS::AutoScaling::AutoScalingGroup'}
        self.assertEqual(initial_resources,
                         self.list_resources(stack_identifier))

        stack = self.client.stacks.get(stack_identifier)
        self.assert_instance_count(stack, 4)

    def test_size_updates_work(self):
        files = {'provider.yaml': self.instance_template}
        env = {'resource_registry': {'AWS::EC2::Instance': 'provider.yaml'},
               'parameters': {'size': 2,
                              'image': self.conf.image_ref,
                              'flavor': self.conf.instance_type}}

        stack_identifier = self.stack_create(template=self.template,
                                             files=files,
                                             environment=env)
        stack = self.client.stacks.get(stack_identifier)
        self.assert_instance_count(stack, 2)

        # Increase min size to 5
        env2 = {'resource_registry': {'AWS::EC2::Instance': 'provider.yaml'},
                'parameters': {'size': 5,
                               'image': self.conf.image_ref,
                               'flavor': self.conf.instance_type}}
        self.update_stack(stack_identifier, self.template,
                          environment=env2, files=files)
        self._wait_for_stack_status(stack_identifier, 'UPDATE_COMPLETE')
        stack = self.client.stacks.get(stack_identifier)
        self.assert_instance_count(stack, 5)

    def test_update_group_replace(self):
        """Make sure that during a group update the non updatable
        properties cause a replacement.
        """
        files = {'provider.yaml': self.instance_template}
        env = {'resource_registry':
               {'AWS::EC2::Instance': 'provider.yaml'},
               'parameters': {'size': '1',
                              'image': self.conf.image_ref,
                              'flavor': self.conf.instance_type}}

        stack_identifier = self.stack_create(template=self.template,
                                             files=files,
                                             environment=env)
        rsrc = self.client.resources.get(stack_identifier, 'JobServerGroup')
        orig_asg_id = rsrc.physical_resource_id

        env2 = {'resource_registry':
                {'AWS::EC2::Instance': 'provider.yaml'},
                'parameters': {'size': '1',
                               'AZ': 'wibble',
                               'image': self.conf.image_ref,
                               'flavor': self.conf.instance_type}}
        self.update_stack(stack_identifier, self.template,
                          environment=env2, files=files)

        # replacement will cause the resource physical_resource_id to change.
        rsrc = self.client.resources.get(stack_identifier, 'JobServerGroup')
        self.assertNotEqual(orig_asg_id, rsrc.physical_resource_id)

    def test_create_instance_error_causes_group_error(self):
        """If a resource in an instance group fails to be created, the instance
        group itself will fail and the broken inner resource will remain.
        """
        stack_name = self._stack_rand_name()
        files = {'provider.yaml': self.bad_instance_template}
        env = {'resource_registry': {'AWS::EC2::Instance': 'provider.yaml'},
               'parameters': {'size': 2,
                              'image': self.conf.image_ref,
                              'flavor': self.conf.instance_type}}

        self.client.stacks.create(
            stack_name=stack_name,
            template=self.template,
            files=files,
            disable_rollback=True,
            parameters={},
            environment=env
        )
        self.addCleanup(self.client.stacks.delete, stack_name)
        stack = self.client.stacks.get(stack_name)
        stack_identifier = '%s/%s' % (stack_name, stack.id)
        self._wait_for_stack_status(stack_identifier, 'CREATE_FAILED')
        initial_resources = {
            'JobServerConfig': 'AWS::AutoScaling::LaunchConfiguration',
            'JobServerGroup': 'AWS::AutoScaling::AutoScalingGroup'}
        self.assertEqual(initial_resources,
                         self.list_resources(stack_identifier))

        nested_ident = self.assert_resource_is_a_stack(stack_identifier,
                                                       'JobServerGroup')
        self._assert_instance_state(nested_ident, 0, 2)

    def test_update_instance_error_causes_group_error(self):
        """If a resource in an instance group fails to be created during an
        update, the instance group itself will fail and the broken inner
        resource will remain.
        """
        files = {'provider.yaml': self.instance_template}
        env = {'resource_registry': {'AWS::EC2::Instance': 'provider.yaml'},
               'parameters': {'size': 2,
                              'image': self.conf.image_ref,
                              'flavor': self.conf.instance_type}}

        stack_identifier = self.stack_create(template=self.template,
                                             files=files,
                                             environment=env)
        initial_resources = {
            'JobServerConfig': 'AWS::AutoScaling::LaunchConfiguration',
            'JobServerGroup': 'AWS::AutoScaling::AutoScalingGroup'}
        self.assertEqual(initial_resources,
                         self.list_resources(stack_identifier))

        stack = self.client.stacks.get(stack_identifier)
        self.assert_instance_count(stack, 2)
        nested_ident = self.assert_resource_is_a_stack(stack_identifier,
                                                       'JobServerGroup')
        self._assert_instance_state(nested_ident, 2, 0)
        initial_list = [res.resource_name
                        for res in self.client.resources.list(nested_ident)]

        env['parameters']['size'] = 3
        files2 = {'provider.yaml': self.bad_instance_template}
        self.client.stacks.update(
            stack_id=stack_identifier,
            template=self.template,
            files=files2,
            disable_rollback=True,
            parameters={},
            environment=env
        )
        self._wait_for_stack_status(stack_identifier, 'UPDATE_FAILED')

        # assert that there are 3 bad instances
        nested_ident = self.assert_resource_is_a_stack(stack_identifier,
                                                       'JobServerGroup')

        # 2 resources should be in update failed, and one create failed.
        for res in self.client.resources.list(nested_ident):
            if res.resource_name in initial_list:
                self._wait_for_resource_status(nested_ident,
                                               res.resource_name,
                                               'UPDATE_FAILED')
            else:
                self._wait_for_resource_status(nested_ident,
                                               res.resource_name,
                                               'CREATE_FAILED')

    def test_group_suspend_resume(self):

        files = {'provider.yaml': self.instance_template}
        env = {'resource_registry': {'AWS::EC2::Instance': 'provider.yaml'},
               'parameters': {'size': 4,
                              'image': self.conf.image_ref,
                              'flavor': self.conf.instance_type}}
        stack_identifier = self.stack_create(template=self.template,
                                             files=files, environment=env)

        nested_ident = self.assert_resource_is_a_stack(stack_identifier,
                                                       'JobServerGroup')

        self.client.actions.suspend(stack_id=stack_identifier)
        self._wait_for_resource_status(
            stack_identifier, 'JobServerGroup', 'SUSPEND_COMPLETE')
        for res in self.client.resources.list(nested_ident):
            self._wait_for_resource_status(nested_ident,
                                           res.resource_name,
                                           'SUSPEND_COMPLETE')

        self.client.actions.resume(stack_id=stack_identifier)
        self._wait_for_resource_status(
            stack_identifier, 'JobServerGroup', 'RESUME_COMPLETE')
        for res in self.client.resources.list(nested_ident):
            self._wait_for_resource_status(nested_ident,
                                           res.resource_name,
                                           'RESUME_COMPLETE')


class AutoscalingGroupUpdatePolicyTest(AutoscalingGroupTest):

    def ig_tmpl_with_updt_policy(self):
        templ = json.loads(copy.deepcopy(self.template))
        up = {"AutoScalingRollingUpdate": {
            "MinInstancesInService": "1",
            "MaxBatchSize": "2",
            "PauseTime": "PT1S"}}
        templ['Resources']['JobServerGroup']['UpdatePolicy'] = up
        return templ

    def update_instance_group(self, updt_template,
                              num_updates_expected_on_updt,
                              num_creates_expected_on_updt,
                              num_deletes_expected_on_updt,
                              update_replace):

        # setup stack from the initial template
        files = {'provider.yaml': self.instance_template}
        size = 10
        env = {'resource_registry': {'AWS::EC2::Instance': 'provider.yaml'},
               'parameters': {'size': size,
                              'image': self.conf.image_ref,
                              'flavor': self.conf.instance_type}}
        stack_name = self._stack_rand_name()
        stack_identifier = self.stack_create(
            stack_name=stack_name,
            template=self.ig_tmpl_with_updt_policy(),
            files=files,
            environment=env)
        stack = self.client.stacks.get(stack_identifier)
        nested_ident = self.assert_resource_is_a_stack(stack_identifier,
                                                       'JobServerGroup')

        # test that physical resource name of launch configuration is used
        conf_name = self._stack_output(stack, 'JobServerConfigRef')
        conf_name_pattern = '%s-JobServerConfig-[a-zA-Z0-9]+$' % stack_name
        self.assertThat(conf_name,
                        matchers.MatchesRegex(conf_name_pattern))

        # test the number of instances created
        self.assert_instance_count(stack, size)
        # saves info from initial list of instances for comparison later
        init_instances = self.client.resources.list(nested_ident)
        init_names = [inst.resource_name for inst in init_instances]

        # test stack update
        self.update_stack(stack_identifier, updt_template,
                          environment=env, files=files)
        self._wait_for_stack_status(stack_identifier, 'UPDATE_COMPLETE')
        updt_stack = self.client.stacks.get(stack_identifier)

        # test that the launch configuration is replaced
        updt_conf_name = self._stack_output(updt_stack, 'JobServerConfigRef')
        self.assertThat(updt_conf_name,
                        matchers.MatchesRegex(conf_name_pattern))
        self.assertNotEqual(conf_name, updt_conf_name)

        # test that the group size are the same
        updt_instances = self.client.resources.list(nested_ident)
        updt_names = [inst.resource_name for inst in updt_instances]
        self.assertEqual(len(init_names), len(updt_names))
        for res in updt_instances:
            self.assertEqual('UPDATE_COMPLETE', res.resource_status)

        # test that the appropriate number of instance names are the same
        matched_names = set(updt_names) & set(init_names)
        self.assertEqual(num_updates_expected_on_updt, len(matched_names))

        # test that the appropriate number of new instances are created
        self.assertEqual(num_creates_expected_on_updt,
                         len(set(updt_names) - set(init_names)))

        # test that the appropriate number of instances are deleted
        self.assertEqual(num_deletes_expected_on_updt,
                         len(set(init_names) - set(updt_names)))

        # test that the older instances are the ones being deleted
        if num_deletes_expected_on_updt > 0:
            deletes_expected = init_names[:num_deletes_expected_on_updt]
            self.assertNotIn(deletes_expected, updt_names)

    def test_instance_group_update_replace(self):
        """
        Test simple update replace with no conflict in batch size and
        minimum instances in service.
        """
        updt_template = self.ig_tmpl_with_updt_policy()
        grp = updt_template['Resources']['JobServerGroup']
        policy = grp['UpdatePolicy']['AutoScalingRollingUpdate']
        policy['MinInstancesInService'] = '1'
        policy['MaxBatchSize'] = '3'
        config = updt_template['Resources']['JobServerConfig']
        config['Properties']['ImageId'] = self.conf.minimal_image_ref

        self.update_instance_group(updt_template,
                                   num_updates_expected_on_updt=10,
                                   num_creates_expected_on_updt=0,
                                   num_deletes_expected_on_updt=0,
                                   update_replace=True)

    def test_instance_group_update_replace_with_adjusted_capacity(self):
        """
        Test update replace with capacity adjustment due to conflict in
        batch size and minimum instances in service.
        """
        updt_template = self.ig_tmpl_with_updt_policy()
        grp = updt_template['Resources']['JobServerGroup']
        policy = grp['UpdatePolicy']['AutoScalingRollingUpdate']
        policy['MinInstancesInService'] = '8'
        policy['MaxBatchSize'] = '4'
        config = updt_template['Resources']['JobServerConfig']
        config['Properties']['ImageId'] = self.conf.minimal_image_ref

        self.update_instance_group(updt_template,
                                   num_updates_expected_on_updt=8,
                                   num_creates_expected_on_updt=2,
                                   num_deletes_expected_on_updt=2,
                                   update_replace=True)

    def test_instance_group_update_replace_huge_batch_size(self):
        """
        Test update replace with a huge batch size.
        """
        updt_template = self.ig_tmpl_with_updt_policy()
        group = updt_template['Resources']['JobServerGroup']
        policy = group['UpdatePolicy']['AutoScalingRollingUpdate']
        policy['MinInstancesInService'] = '0'
        policy['MaxBatchSize'] = '20'
        config = updt_template['Resources']['JobServerConfig']
        config['Properties']['ImageId'] = self.conf.minimal_image_ref

        self.update_instance_group(updt_template,
                                   num_updates_expected_on_updt=10,
                                   num_creates_expected_on_updt=0,
                                   num_deletes_expected_on_updt=0,
                                   update_replace=True)

    def test_instance_group_update_replace_huge_min_in_service(self):
        """
        Test update replace with a huge number of minimum instances in service.
        """
        updt_template = self.ig_tmpl_with_updt_policy()
        group = updt_template['Resources']['JobServerGroup']
        policy = group['UpdatePolicy']['AutoScalingRollingUpdate']
        policy['MinInstancesInService'] = '20'
        policy['MaxBatchSize'] = '1'
        policy['PauseTime'] = 'PT0S'
        config = updt_template['Resources']['JobServerConfig']
        config['Properties']['ImageId'] = self.conf.minimal_image_ref

        self.update_instance_group(updt_template,
                                   num_updates_expected_on_updt=9,
                                   num_creates_expected_on_updt=1,
                                   num_deletes_expected_on_updt=1,
                                   update_replace=True)

    def test_instance_group_update_no_replace(self):
        """
        Test simple update only and no replace (i.e. updated instance flavor
        in Launch Configuration) with no conflict in batch size and
        minimum instances in service.
        """
        updt_template = self.ig_tmpl_with_updt_policy()
        group = updt_template['Resources']['JobServerGroup']
        policy = group['UpdatePolicy']['AutoScalingRollingUpdate']
        policy['MinInstancesInService'] = '1'
        policy['MaxBatchSize'] = '3'
        policy['PauseTime'] = 'PT0S'
        config = updt_template['Resources']['JobServerConfig']
        config['Properties']['InstanceType'] = 'm1.tiny'

        self.update_instance_group(updt_template,
                                   num_updates_expected_on_updt=10,
                                   num_creates_expected_on_updt=0,
                                   num_deletes_expected_on_updt=0,
                                   update_replace=False)

    def test_instance_group_update_no_replace_with_adjusted_capacity(self):
        """
        Test update only and no replace (i.e. updated instance flavor in
        Launch Configuration) with capacity adjustment due to conflict in
        batch size and minimum instances in service.
        """
        updt_template = self.ig_tmpl_with_updt_policy()
        group = updt_template['Resources']['JobServerGroup']
        policy = group['UpdatePolicy']['AutoScalingRollingUpdate']
        policy['MinInstancesInService'] = '8'
        policy['MaxBatchSize'] = '4'
        policy['PauseTime'] = 'PT0S'
        config = updt_template['Resources']['JobServerConfig']
        config['Properties']['InstanceType'] = 'm1.tiny'

        self.update_instance_group(updt_template,
                                   num_updates_expected_on_updt=8,
                                   num_creates_expected_on_updt=2,
                                   num_deletes_expected_on_updt=2,
                                   update_replace=False)


class AutoScalingSignalTest(AutoscalingGroupTest):

    template = '''
{
  "AWSTemplateFormatVersion" : "2010-09-09",
  "Description" : "Template to create multiple instances.",
  "Parameters" : {"size": {"Type": "String", "Default": "1"},
                  "AZ": {"Type": "String", "Default": "nova"},
                  "image": {"Type": "String"},
                  "flavor": {"Type": "String"}},
  "Resources": {
    "custom_lb": {
      "Type": "AWS::EC2::Instance",
      "Properties": {
        "ImageId": {"Ref": "image"},
        "InstanceType": {"Ref": "flavor"},
        "UserData": "foo",
        "SecurityGroups": [ "sg-1" ],
        "Tags": []
      },
      "Metadata": {
        "IPs": {"Fn::GetAtt": ["JobServerGroup", "InstanceList"]}
      }
    },
    "JobServerGroup": {
      "Type" : "AWS::AutoScaling::AutoScalingGroup",
      "Properties" : {
        "AvailabilityZones" : [{"Ref": "AZ"}],
        "LaunchConfigurationName" : { "Ref" : "JobServerConfig" },
        "DesiredCapacity" : {"Ref": "size"},
        "MinSize" : "0",
        "MaxSize" : "20"
      }
    },
    "JobServerConfig" : {
      "Type" : "AWS::AutoScaling::LaunchConfiguration",
      "Metadata": {"foo": "bar"},
      "Properties": {
        "ImageId"           : {"Ref": "image"},
        "InstanceType"      : {"Ref": "flavor"},
        "SecurityGroups"    : [ "sg-1" ],
        "UserData"          : "jsconfig data"
      }
    },
    "ScaleUpPolicy" : {
      "Type" : "AWS::AutoScaling::ScalingPolicy",
      "Properties" : {
        "AdjustmentType" : "ChangeInCapacity",
        "AutoScalingGroupName" : { "Ref" : "JobServerGroup" },
        "Cooldown" : "0",
        "ScalingAdjustment": "1"
      }
    },
    "ScaleDownPolicy" : {
      "Type" : "AWS::AutoScaling::ScalingPolicy",
      "Properties" : {
        "AdjustmentType" : "ChangeInCapacity",
        "AutoScalingGroupName" : { "Ref" : "JobServerGroup" },
        "Cooldown" : "0",
        "ScalingAdjustment" : "-2"
      }
    }
  },
  "Outputs": {
    "InstanceList": {"Value": {
      "Fn::GetAtt": ["JobServerGroup", "InstanceList"]}}
  }
}
'''

    lb_template = '''
heat_template_version: 2013-05-23
parameters:
  ImageId: {type: string}
  InstanceType: {type: string}
  SecurityGroups: {type: comma_delimited_list}
  UserData: {type: string}
  Tags: {type: comma_delimited_list}

resources:
outputs:
  PublicIp: {value: "not-used"}
  AvailabilityZone: {value: 'not-used1'}
  PrivateDnsName: {value: 'not-used2'}
  PublicDnsName: {value: 'not-used3'}
  PrivateIp: {value: 'not-used4'}

'''

    def setUp(self):
        super(AutoScalingSignalTest, self).setUp()
        self.build_timeout = self.conf.build_timeout
        self.build_interval = self.conf.build_interval
        self.files = {'provider.yaml': self.instance_template,
                      'lb.yaml': self.lb_template}
        self.env = {'resource_registry':
                    {'resources':
                     {'custom_lb': {'AWS::EC2::Instance': 'lb.yaml'}},
                     'AWS::EC2::Instance': 'provider.yaml'},
                    'parameters': {'size': 2,
                                   'image': self.conf.image_ref,
                                   'flavor': self.conf.instance_type}}

    def check_instance_count(self, stack_identifier, expected):
        md = self.client.resources.metadata(stack_identifier, 'custom_lb')
        actual_md = len(md['IPs'].split(','))
        if actual_md != expected:
            LOG.warn('check_instance_count exp:%d, meta:%s' % (expected,
                                                               md['IPs']))
            return False

        stack = self.client.stacks.get(stack_identifier)
        inst_list = self._stack_output(stack, 'InstanceList')
        actual = len(inst_list.split(','))
        if actual != expected:
            LOG.warn('check_instance_count exp:%d, act:%s' % (expected,
                                                              inst_list))
        return actual == expected

    def test_scaling_meta_update(self):
        """Use heatclient to signal the up and down policy.

        Then confirm that the metadata in the custom_lb is updated each
        time.
        """
        stack_identifier = self.stack_create(template=self.template,
                                             files=self.files,
                                             environment=self.env)

        self.assertTrue(test.call_until_true(
            self.build_timeout, self.build_interval,
            self.check_instance_count, stack_identifier, 2))

        nested_ident = self.assert_resource_is_a_stack(stack_identifier,
                                                       'JobServerGroup')
        # Scale up one, Trigger alarm
        self.client.resources.signal(stack_identifier, 'ScaleUpPolicy')
        self._wait_for_stack_status(nested_ident, 'UPDATE_COMPLETE')
        self.assertTrue(test.call_until_true(
            self.build_timeout, self.build_interval,
            self.check_instance_count, stack_identifier, 3))

        # Scale down two, Trigger alarm
        self.client.resources.signal(stack_identifier, 'ScaleDownPolicy')
        self._wait_for_stack_status(nested_ident, 'UPDATE_COMPLETE')
        self.assertTrue(test.call_until_true(
            self.build_timeout, self.build_interval,
            self.check_instance_count, stack_identifier, 1))

    def test_signal_with_policy_update(self):
        """Prove that an updated policy is used in the next signal."""

        stack_identifier = self.stack_create(template=self.template,
                                             files=self.files,
                                             environment=self.env)

        self.assertTrue(test.call_until_true(
            self.build_timeout, self.build_interval,
            self.check_instance_count, stack_identifier, 2))

        nested_ident = self.assert_resource_is_a_stack(stack_identifier,
                                                       'JobServerGroup')
        # Scale up one, Trigger alarm
        self.client.resources.signal(stack_identifier, 'ScaleUpPolicy')
        self._wait_for_stack_status(nested_ident, 'UPDATE_COMPLETE')
        self.assertTrue(test.call_until_true(
            self.build_timeout, self.build_interval,
            self.check_instance_count, stack_identifier, 3))

        # increase the adjustment to "+2" and remove the DesiredCapacity
        # so we don't go from 3 to 2.
        new_template = self.template.replace(
            '"ScalingAdjustment": "1"',
            '"ScalingAdjustment": "2"').replace(
                '"DesiredCapacity" : {"Ref": "size"},', '')

        self.update_stack(stack_identifier, template=new_template,
                          environment=self.env, files=self.files)

        # Scale up two, Trigger alarm
        self.client.resources.signal(stack_identifier, 'ScaleUpPolicy')
        self._wait_for_stack_status(nested_ident, 'UPDATE_COMPLETE')
        self.assertTrue(test.call_until_true(
            self.build_timeout, self.build_interval,
            self.check_instance_count, stack_identifier, 5))