Fix: Adding alarm arn to describe alarms response (#3409)

* Fix: adding alarm arn to describe alarms response

* Fix:Delete subscriptions on delete topic

* modified tests

Co-authored-by: usmankb <usman@krazybee.com>

moto/cloudwatch/models.py

@@ -9,7 +9,7 @@ from moto.logs import logs_backends
 from datetime import datetime, timedelta
 from dateutil.tz import tzutc
 from uuid import uuid4
-from .utils import make_arn_for_dashboard
+from .utils import make_arn_for_dashboard, make_arn_for_alarm
 from dateutil import parser
 
 from moto.core import ACCOUNT_ID as DEFAULT_ACCOUNT_ID
@@ -106,8 +106,10 @@ class FakeAlarm(BaseModel):
         insufficient_data_actions,
         unit,
         actions_enabled,
+        region="us-east-1",
     ):
         self.name = name
+        self.alarm_arn = make_arn_for_alarm(region, DEFAULT_ACCOUNT_ID, name)
         self.namespace = namespace
         self.metric_name = metric_name
         self.metric_data_queries = metric_data_queries
@@ -280,6 +282,7 @@ class CloudWatchBackend(BaseBackend):
         insufficient_data_actions,
         unit,
         actions_enabled,
+        region="us-east-1",
     ):
         alarm = FakeAlarm(
             name,
@@ -299,7 +302,9 @@ class CloudWatchBackend(BaseBackend):
             insufficient_data_actions,
             unit,
             actions_enabled,
+            region,
         )
+
         self.alarms[name] = alarm
         return alarm
 

moto/cloudwatch/responses.py

@@ -80,6 +80,7 @@ class CloudWatchResponse(BaseResponse):
             insufficient_data_actions,
             unit,
             actions_enabled,
+            self.region,
         )
         template = self.response_template(PUT_METRIC_ALARM_TEMPLATE)
         return template.render(alarm=alarm)
@@ -287,7 +288,7 @@ DESCRIBE_ALARMS_TEMPLATE = """<DescribeAlarmsResponse xmlns="http://monitoring.a
                     <member>{{ action }}</member>
                     {% endfor %}
                 </AlarmActions>
-                <AlarmArn>{{ alarm.arn }}</AlarmArn>
+                <AlarmArn>{{ alarm.alarm_arn }}</AlarmArn>
                 <AlarmConfigurationUpdatedTimestamp>{{ alarm.configuration_updated_timestamp }}</AlarmConfigurationUpdatedTimestamp>
                 <AlarmDescription>{{ alarm.description }}</AlarmDescription>
                 <AlarmName>{{ alarm.name }}</AlarmName>
@@ -395,7 +396,7 @@ DESCRIBE_METRIC_ALARMS_TEMPLATE = """<DescribeAlarmsForMetricResponse xmlns="htt
                     <member>{{ action }}</member>
                     {% endfor %}
                 </AlarmActions>
-                <AlarmArn>{{ alarm.arn }}</AlarmArn>
+                <AlarmArn>{{ alarm.alarm_arn }}</AlarmArn>
                 <AlarmConfigurationUpdatedTimestamp>{{ alarm.configuration_updated_timestamp }}</AlarmConfigurationUpdatedTimestamp>
                 <AlarmDescription>{{ alarm.description }}</AlarmDescription>
                 <AlarmName>{{ alarm.name }}</AlarmName>

moto/cloudwatch/utils.py

@@ -3,3 +3,7 @@ from __future__ import unicode_literals
 
 def make_arn_for_dashboard(account_id, name):
     return "arn:aws:cloudwatch::{0}dashboard/{1}".format(account_id, name)
+
+
+def make_arn_for_alarm(region, account_id, alarm_name):
+    return "arn:aws:cloudwatch:{0}:{1}:alarm:{2}".format(region, account_id, alarm_name)

tests/test_cloudwatch/test_cloudwatch.py

@@ -3,6 +3,8 @@ from boto.ec2.cloudwatch.alarm import MetricAlarm
 from boto.s3.key import Key
 from datetime import datetime
 import sure  # noqa
+from moto.cloudwatch.utils import make_arn_for_alarm
+from moto.core import ACCOUNT_ID
 
 from moto import mock_cloudwatch_deprecated, mock_s3_deprecated
 
@@ -51,6 +53,7 @@ def test_create_alarm():
     list(alarm.ok_actions).should.equal(["arn:ok"])
     list(alarm.insufficient_data_actions).should.equal(["arn:insufficient"])
     alarm.unit.should.equal("Seconds")
+    assert "tester" in alarm.alarm_arn
 
 
 @mock_cloudwatch_deprecated

tests/test_cloudwatch/test_cloudwatch_boto3.py

@@ -10,6 +10,8 @@ import pytz
 import sure  # noqa
 
 from moto import mock_cloudwatch
+from moto.cloudwatch.utils import make_arn_for_alarm
+from moto.core import ACCOUNT_ID
 
 
 @mock_cloudwatch
@@ -140,6 +142,8 @@ def test_describe_alarms_for_metric():
     alarms = conn.describe_alarms_for_metric(MetricName="cpu", Namespace="blah")
     alarms.get("MetricAlarms").should.have.length_of(1)
 
+    assert "testalarm1" in alarms.get("MetricAlarms")[0].get("AlarmArn")
+
 
 @mock_cloudwatch
 def test_describe_alarms():