add support for Fn::GetAtt in event's cloudformation

moto/events/models.py

@@ -59,6 +59,14 @@ class Rule(BaseModel):
             if index is not None:
                 self.targets.pop(index)
 
+    def get_cfn_attribute(self, attribute_name):
+        from moto.cloudformation.exceptions import UnformattedGetAttTemplateException
+
+        if attribute_name == "Arn":
+            return self.arn
+
+        raise UnformattedGetAttTemplateException()
+
     @classmethod
     def create_from_cloudformation_json(
         cls, resource_name, cloudformation_json, region_name

tests/test_cloudformation/test_cloudformation_stack_integration.py

@@ -2463,3 +2463,40 @@ def test_stack_events_create_rule_without_name_integration():
 
     rules = boto3.client("events", "us-west-2").list_rules()
     rules["Rules"][0]["Name"].should.contain("test_stack-Event-")
+
+
+@mock_cloudformation
+@mock_events
+@mock_logs
+def test_stack_events_create_rule_as_target():
+    events_template = {
+        "AWSTemplateFormatVersion": "2010-09-09",
+        "Resources": {
+            "SecurityGroup": {
+                "Type": "AWS::Logs::LogGroup",
+                "Properties": {
+                    "LogGroupName": {"Fn::GetAtt": ["Event", "Arn"]},
+                    "RetentionInDays": 3,
+                }
+            },
+            "Event": {
+                "Type": "AWS::Events::Rule",
+                "Properties": {
+                    "State": "ENABLED",
+                    "ScheduleExpression": "rate(5 minutes)",
+                },
+            }
+        },
+    }
+    cf_conn = boto3.client("cloudformation", "us-west-2")
+    cf_conn.create_stack(
+        StackName="test_stack", TemplateBody=json.dumps(events_template),
+    )
+
+    rules = boto3.client("events", "us-west-2").list_rules()
+    log_groups = boto3.client("logs", "us-west-2").describe_log_groups()
+
+    rules["Rules"][0]["Name"].should.contain("test_stack-Event-")
+
+    log_groups["logGroups"][0]["logGroupName"].should.equal(rules["Rules"][0]["Arn"])
+    log_groups["logGroups"][0]["retentionInDays"].should.equal(3)