Support getting cloudformation targets for the SSM backend.

SendCommand allows filtering for instances by tags. This adds support
for filtering by a cloud formation stack resource when creating command
invocations.

tests/test_ssm/test_ssm_boto3.py

@@ -5,11 +5,12 @@ import botocore.exceptions
 import sure   # noqa
 import datetime
 import uuid
+import json
 
 from botocore.exceptions import ClientError
 from nose.tools import assert_raises
 
-from moto import mock_ssm
+from moto import mock_ssm, mock_cloudformation
 
 
 @mock_ssm
@@ -708,3 +709,78 @@ def test_get_command_invocation():
             CommandId=cmd_id,
             InstanceId=instance_id,
             PluginName='FAKE')
+
+@mock_ssm
+@mock_cloudformation
+def test_get_command_invocations_from_stack():
+    stack_template = {
+        "AWSTemplateFormatVersion": "2010-09-09",
+        "Description": "Test Stack",
+        "Resources": {
+            "EC2Instance1": {
+                "Type": "AWS::EC2::Instance",
+                "Properties": {
+                    "ImageId": "ami-test-image-id",
+                    "KeyName": "test",
+                    "InstanceType": "t2.micro",
+                    "Tags": [
+                        {
+                            "Key": "Test Description",
+                            "Value": "Test tag"
+                        },
+                        {
+                            "Key": "Test Name",
+                            "Value": "Name tag for tests"
+                        }
+                    ]
+                }
+            }
+        },
+        "Outputs": {
+            "test": {
+                "Description": "Test Output",
+                "Value": "Test output value",
+                "Export": {
+                    "Name": "Test value to export"
+                }
+            },
+            "PublicIP": {
+                "Value": "Test public ip"
+            }
+        }
+    }
+
+    cloudformation_client = boto3.client(
+        'cloudformation',
+        region_name='us-east-1')
+
+    stack_template_str = json.dumps(stack_template)
+
+    response = cloudformation_client.create_stack(
+        StackName='test_stack',
+        TemplateBody=stack_template_str,
+        Capabilities=('CAPABILITY_IAM', ))
+
+    client = boto3.client('ssm', region_name='us-east-1')
+
+    ssm_document = 'AWS-RunShellScript'
+    params = {'commands': ['#!/bin/bash\necho \'hello world\'']}
+
+    response = client.send_command(
+        Targets=[{
+            'Key': 'tag:aws:cloudformation:stack-name',
+            'Values': ('test_stack', )}],
+        DocumentName=ssm_document,
+        Parameters=params,
+        OutputS3Region='us-east-2',
+        OutputS3BucketName='the-bucket',
+        OutputS3KeyPrefix='pref')
+
+    cmd = response['Command']
+    cmd_id = cmd['CommandId']
+    instance_ids = cmd['InstanceIds']
+
+    invocation_response = client.get_command_invocation(
+        CommandId=cmd_id,
+        InstanceId=instance_ids[0],
+        PluginName='aws:runShellScript')