From cb72d1d00e7dadf7e1089a73a8372c57a4259afa Mon Sep 17 00:00:00 2001
From: Jon Beilke <jrbeilke@gmail.com>
Date: Sat, 25 May 2019 04:14:23 -0500
Subject: [PATCH] Feature cloudwatch log retention (#2199)

* add proper retentionInDays to describe_log_groups response and add support for delete_retention_policy() and put_retention_policy() to log groups

* fix for inline comment formatting

* include check for retentionInDays to verify no retention by default in  test_log_group_create
---
 moto/logs/models.py          | 23 +++++++++++++++++++++--
 moto/logs/responses.py       | 11 +++++++++++
 tests/test_logs/test_logs.py | 36 ++++++++++++++++++++++++++++++++++++
 3 files changed, 68 insertions(+), 2 deletions(-)

diff --git a/moto/logs/models.py b/moto/logs/models.py
index e105d4d14..a44b76812 100644
--- a/moto/logs/models.py
+++ b/moto/logs/models.py
@@ -137,6 +137,7 @@ class LogGroup:
         self.creationTime = unix_time_millis()
         self.tags = tags
         self.streams = dict()  # {name: LogStream}
+        self.retentionInDays = None  # AWS defaults to Never Expire for log group retention
 
     def create_log_stream(self, log_stream_name):
         if log_stream_name in self.streams:
@@ -201,14 +202,20 @@ class LogGroup:
         return events_page, next_token, searched_streams
 
     def to_describe_dict(self):
-        return {
+        log_group = {
             "arn": self.arn,
             "creationTime": self.creationTime,
             "logGroupName": self.name,
             "metricFilterCount": 0,
-            "retentionInDays": 30,
             "storedBytes": sum(s.storedBytes for s in self.streams.values()),
         }
+        # AWS only returns retentionInDays if a value is set for the log group (ie. not Never Expire)
+        if self.retentionInDays:
+            log_group["retentionInDays"] = self.retentionInDays
+        return log_group
+
+    def set_retention_policy(self, retention_in_days):
+        self.retentionInDays = retention_in_days
 
 
 class LogsBackend(BaseBackend):
@@ -289,5 +296,17 @@ class LogsBackend(BaseBackend):
         log_group = self.groups[log_group_name]
         return log_group.filter_log_events(log_group_name, log_stream_names, start_time, end_time, limit, next_token, filter_pattern, interleaved)
 
+    def put_retention_policy(self, log_group_name, retention_in_days):
+        if log_group_name not in self.groups:
+            raise ResourceNotFoundException()
+        log_group = self.groups[log_group_name]
+        return log_group.set_retention_policy(retention_in_days)
+
+    def delete_retention_policy(self, log_group_name):
+        if log_group_name not in self.groups:
+            raise ResourceNotFoundException()
+        log_group = self.groups[log_group_name]
+        return log_group.set_retention_policy(None)
+
 
 logs_backends = {region.name: LogsBackend(region.name) for region in boto.logs.regions()}
diff --git a/moto/logs/responses.py b/moto/logs/responses.py
index 4bec86cb2..39f24a260 100644
--- a/moto/logs/responses.py
+++ b/moto/logs/responses.py
@@ -123,3 +123,14 @@ class LogsResponse(BaseResponse):
             "nextToken": next_token,
             "searchedLogStreams": searched_streams
         })
+
+    def put_retention_policy(self):
+        log_group_name = self._get_param('logGroupName')
+        retention_in_days = self._get_param('retentionInDays')
+        self.logs_backend.put_retention_policy(log_group_name, retention_in_days)
+        return ''
+
+    def delete_retention_policy(self):
+        log_group_name = self._get_param('logGroupName')
+        self.logs_backend.delete_retention_policy(log_group_name)
+        return ''
diff --git a/tests/test_logs/test_logs.py b/tests/test_logs/test_logs.py
index e3d46fd87..7048061f0 100644
--- a/tests/test_logs/test_logs.py
+++ b/tests/test_logs/test_logs.py
@@ -17,6 +17,8 @@ def test_log_group_create():
 
     response = conn.describe_log_groups(logGroupNamePrefix=log_group_name)
     assert len(response['logGroups']) == 1
+    # AWS defaults to Never Expire for log group retention
+    assert response['logGroups'][0].get('retentionInDays') == None
 
     response = conn.delete_log_group(logGroupName=log_group_name)
 
@@ -126,3 +128,37 @@ def test_filter_logs_interleaved():
         resulting_event['timestamp'].should.equal(original_message['timestamp'])
         resulting_event['message'].should.equal(original_message['message'])
 
+@mock_logs
+def test_put_retention_policy():
+    conn = boto3.client('logs', 'us-west-2')
+    log_group_name = 'dummy'
+    response = conn.create_log_group(logGroupName=log_group_name)
+
+    response = conn.put_retention_policy(logGroupName=log_group_name, retentionInDays=7)
+
+    response = conn.describe_log_groups(logGroupNamePrefix=log_group_name)
+    assert len(response['logGroups']) == 1
+    assert response['logGroups'][0].get('retentionInDays') == 7
+
+    response = conn.delete_log_group(logGroupName=log_group_name)
+
+@mock_logs
+def test_delete_retention_policy():
+    conn = boto3.client('logs', 'us-west-2')
+    log_group_name = 'dummy'
+    response = conn.create_log_group(logGroupName=log_group_name)
+
+    response = conn.put_retention_policy(logGroupName=log_group_name, retentionInDays=7)
+
+    response = conn.describe_log_groups(logGroupNamePrefix=log_group_name)
+    assert len(response['logGroups']) == 1
+    assert response['logGroups'][0].get('retentionInDays') == 7
+
+    response = conn.delete_retention_policy(logGroupName=log_group_name)
+
+    response = conn.describe_log_groups(logGroupNamePrefix=log_group_name)
+    assert len(response['logGroups']) == 1
+    assert response['logGroups'][0].get('retentionInDays') == None
+
+    response = conn.delete_log_group(logGroupName=log_group_name)
+