Ability to place a stack into maintenance mode zalando-stups#443

Given a stack it will detect all asgs within that stack
negates the tag named 'maintenance' and do the same
on all instances currently belonging to that asg.

$ senza maintenance some-stack-name
Changing maintenance mode on Auto Scaling Group some-stack-name-version-AppServer-1R2KFL5HLI5NT..
Maintance mode set to False for some-stack-name-version-AppServer-1R2KFL5HLI5NT

$ senza maintenance some-stack-name
Changing maintenance mode on Auto Scaling Group some-stack-name-version-AppServer-1R2KFL5HLI5NT..
Maintance mode set to True for some-stack-name-version-AppServer-1R2KFL5HLI5NT

Signed-off-by: Ian Duffy <[email protected]>

senza/cli.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+import ast
 import base64
 import calendar
 import collections
@@ -1389,6 +1390,45 @@ def get_auto_scaling_groups(stack_refs, region):
                 yield asg_name
 
 
+@cli.command()
+@click.argument('stack_name')
+@click.argument('stack_version', required=False)
+@region_option
+def maintenance(stack_name, stack_version, region):
+    '''Negates the value of the tag named 'maintenance' across the given stack
+    asg and its instances.'''
+
+    stack_refs = get_stack_refs([stack_name, stack_version])
+    region = get_region(region)
+    check_credentials(region)
+
+    asg = BotoClientProxy('autoscaling', region)
+    ec2 = BotoClientProxy('ec2', region)
+
+    for asg_name in get_auto_scaling_groups(stack_refs, region):
+        with Action('Changing maintenance mode on Auto Scaling Group {}..'.format(asg_name)) as act:
+            result = asg.describe_auto_scaling_groups(AutoScalingGroupNames=[asg_name])
+            groups = result['AutoScalingGroups']
+            for group in groups:
+                result = [tag['Value'] for tag in group['Tags'] if tag['Key'] == 'maintenance']
+                result = 'false' if not result else not ast.literal_eval(result[0])
+                ec2.create_tags(
+                    Resources=[instance['InstanceId'] for instance in group['Instances']],
+                    Tags=[{
+                        'Key': 'maintenance',
+                        'Value': str(result)
+                    }]
+                )
+                asg.create_or_update_tags(Tags=[{
+                    'ResourceId': group['AutoScalingGroupName'],
+                    'ResourceType': 'auto-scaling-group',
+                    'Key': 'maintenance',
+                    'Value': str(result),
+                    'PropagateAtLaunch': True
+                }])
+                act.ok('\nMaintance mode set to {} for {}'.format(result, asg_name))
+
+
 @cli.command()
 @click.argument('stack_ref', nargs=-1)
 @region_option

tests/test_cli.py

@@ -1501,6 +1501,24 @@ def test_AccountArguments(monkeypatch):
     assert test.Domain == 'example.net'
     assert test.TeamID == 'cli'
 
+def test_maintenance(monkeypatch):
+  boto3 = MagicMock()
+  boto3.list_stacks.return_value = {'StackSummaries': [{'StackName': 'myapp-1',
+                                                          'CreationTime': '2016-06-14'}]}
+  boto3.describe_stack_resources.return_value = {'StackResources':
+                                                     [{'ResourceType': 'AWS::AutoScaling::AutoScalingGroup',
+                                                       'PhysicalResourceId': 'myasg'}]}
+  instance = {'InstanceId': 'MyInstance'}
+  group = {'AutoScalingGroupName': 'myasg', 'Instances': [instance], 'Tags': []}
+  boto3.describe_auto_scaling_groups.return_value = {'AutoScalingGroups': [group]}
+
+  monkeypatch.setattr('boto3.client', MagicMock(return_value=boto3))
+
+  runner = CliRunner()
+  result = runner.invoke(cli, ['maintenance', 'myapp', '1', '--region=aa-fakeregion-1'],
+                         catch_exceptions=False)
+
+  assert 'Changing maintenance mode on Auto Scaling Group' in result.output
 
 def test_patch(monkeypatch):
     boto3 = MagicMock()