bug: Do not check 'metrics' instance for draining

Also fixed some flake8 errors

closes #59

ardere/aws.py

@@ -1,5 +1,4 @@
 """AWS Helper Classes"""
-import json
 import logging
 import os
 import time
@@ -9,13 +8,7 @@
 import boto3
 import botocore
 from concurrent.futures import ThreadPoolExecutor
-from typing import (
-    Any,
-    Dict,
-    List,
-    Optional,
-    Tuple
-)  # noqa
+from typing import Any, Dict, List, Optional, Tuple  # noqa
 
 logger = logging.getLogger()
 logger.setLevel(logging.INFO)
@@ -314,7 +307,7 @@ def request_instances(self, instances, security_group_ids,
     def locate_metrics_container_ip(self):
         # type: () -> Tuple[Optional[str], Optional[str]]
         """Locates the metrics container IP and container instance arn
-        
+
         Returns a tuple of (public_ip, container_arn)
 
         """

ardere/scripts/__init__.py

@@ -1,2 +1 @@
 #
-

ardere/step_functions.py

@@ -1,4 +1,3 @@
-import json
 import logging
 import os
 import re
@@ -7,7 +6,6 @@
 
 import boto3
 import botocore
-import requests
 import toml
 from marshmallow import (
     Schema,
@@ -279,7 +277,8 @@ def ensure_metric_sources_created(self):
             raise CreatingMetricSourceException("Started metric creation")
 
         if not self.ecs.has_finished_metric_creation():
-            raise CreatingMetricSourceException("Metric creation still running")
+            raise CreatingMetricSourceException("Metric creation still "
+                                                "running")
 
         metric_ip = self.event["influxdb_private_ip"]
         self.event["grafana_dashboard"] = "http://{}:3000".format(metric_ip)
@@ -368,15 +367,23 @@ def check_drained(self):
 
         """
         client = self.boto.client('ecs')
-        actives = len(
-            client.list_container_instances(
-                cluster=self.event["ecs_name"],
-                maxResults=1,
-                status="ACTIVE",
-            ).get('containerInstanceArns', []))
-        if actives:
+        actives = client.list_container_instances(
+            cluster=self.event["ecs_name"],
+            maxResults=1,
+            status="ACTIVE",
+        ).get('containerInstanceArns', [])
+        # filter out metric servers
+        if self.event["metrics_options"]["enabled"]:
+            metrics = self.ecs.locate_metrics_service()
+            if metrics:
+                metrics_arn = metrics.get("serviceArn")
+                try:
+                    actives.remove(metrics_arn)
+                except ValueError:
+                    pass
+        if len(actives):
             raise UndrainedInstancesException(
-                "Still {} active.".format(actives))
+                "Still active: {}.".format(actives))
         draining = len(
             client.list_container_instances(
                 cluster=self.event["ecs_name"],
@@ -385,5 +392,5 @@ def check_drained(self):
             ).get('containerInstanceArns', []))
         if draining:
             raise UndrainedInstancesException(
-                "Still {} draining.".format(draining))
+                "Still draining: {}.".format(draining))
         return self.event

tests/test_step_functions.py

@@ -300,6 +300,7 @@ def test_drain_check_active(self):
         mock_client.list_container_instances.return_value = {
             'containerInstanceArns': [
                 'Some-Arn-01234567890',
+                'Metric-Arn-01234567890',
             ],
             "nextToken": "token-8675309"
         }
@@ -325,10 +326,25 @@ def test_drain_check_draining(self):
                       self.runner.check_drained)
 
     def test_drain_check(self):
+        # Include a "metrics" instance to show that we ignore it.
+        self.plan["metrics_options"] = dict(enabled=True)
+        self.mock_ecs.locate_metrics_service.return_value = {
+            "deployments": [{
+                "desiredCount": 1,
+                "runningCount": 1
+            }],
+            "serviceArn": "Metric-Arn-01234567890"
+        }
+
         mock_client = mock.Mock()
         mock_client.list_container_instances.side_effect = [
-            {},
-            {}
+            {  # Actives
+                'containerInstanceArns': [
+                    'Metric-Arn-01234567890',
+                ],
+                "nextToken": "token-8675309"
+            },
+            {}  # Draining
         ]
         self.mock_boto.client.return_value = mock_client
         self.runner.check_drained()