use instance-identity/document URL part to get instanceid and region at once.

helpers/aws.py

@@ -2,6 +2,7 @@ import logging
 import re
 import requests
 from requests.exceptions import RequestException
+import yaml
 import boto.ec2
 
 logger = logging.getLogger(__name__)
@@ -20,19 +21,19 @@ class AWSConnection:
             self.cluster_name = 'unknown'
         try:
             # get the instance id
-            r = requests.get('http://169.254.169.254/latest/meta-data/instance-id', timeout=0.1)
-            if r.ok:
-                self.instance_id = r.content.strip()
-                r = requests.get('http://169.254.169.254/latest/meta-data/placement/availability-zone', timeout=0.1)
-                if r.ok:
-                    # get the region from the availability zone, i.e. eu-west-1 from eu-west-1c
-                    m = re.match(r'(\w+-\w+-\d+)[a-z]+', r.content)
-                    if m:
-                        self.region = m.group(1)
-                        self.available = True
+            r = requests.get('http://169.254.169.254/latest/dynamic/instance-identity/document', timeout=0.1)
         except RequestException:
             logger.info("cannot query AWS meta-data")
-            pass
+            return
+        if r.ok:
+            try:
+                content = yaml.load(r.content)
+                self.instance_id = content['instanceId']
+                self.region = content['region']
+            except Exception as e:
+                logger.info('unable to fetch instance id and region from AWS meta-data: {}'.format(e))
+                return
+            self.available = True
 
     def aws_available(self):
         return self.available

tests/test_aws.py

@@ -43,8 +43,8 @@ class TestAWSConnection(unittest.TestCase):
             raise RequestException("foo")
         result = namedtuple('Request', 'ok content')
         result.ok = True
-        if url.split('/')[-1] == 'availability-zone':
-            result.content = 'eu-west-1c'
+        if url.split('/')[-1] == 'document':
+            result.content = '{\n  "instanceId" : "012345",\n "region" : "eu-west-1"\n}'
         else:
             result.content = 'foo'
         return result