if user does not explicitly set Access Key ID and Secret Access Key then use

boto3's methods as fallback

octodns/provider/route53.py

@@ -232,12 +232,14 @@ class Route53Provider(BaseProvider):
     # health check config.
     HEALTH_CHECK_VERSION = '0001'
 
-    def __init__(self, id, access_key_id, secret_access_key, max_changes=1000,
-                 client_max_attempts=None, *args, **kwargs):
+    def __init__(self, id, access_key_id=None, secret_access_key=None,
+                 max_changes=1000, client_max_attempts=None, *args, **kwargs):
         self.max_changes = max_changes
+        _msg = 'access_key_id={}, secret_access_key=***'.format(access_key_id)
+        if access_key_id is None and secret_access_key is None:
+            _msg = 'auth=fallback'
         self.log = logging.getLogger('Route53Provider[{}]'.format(id))
-        self.log.debug('__init__: id=%s, access_key_id=%s, '
-                       'secret_access_key=***', id, access_key_id)
+        self.log.debug('__init__: id=%s, %s', id, _msg)
         super(Route53Provider, self).__init__(id, *args, **kwargs)
 
         config = None
@@ -246,9 +248,12 @@ class Route53Provider(BaseProvider):
                           client_max_attempts)
             config = Config(retries={'max_attempts': client_max_attempts})
 
-        self._conn = client('route53', aws_access_key_id=access_key_id,
-                            aws_secret_access_key=secret_access_key,
-                            config=config)
+        if access_key_id is None and secret_access_key is None:
+            self._conn = client('route53', config=config)
+        else:
+            self._conn = client('route53', aws_access_key_id=access_key_id,
+                                aws_secret_access_key=secret_access_key,
+                                config=config)
 
         self._r53_zones = None
         self._r53_rrsets = {}

tests/test_octodns_provider_route53.py

@@ -167,6 +167,23 @@ class TestRoute53Provider(TestCase):
 
         return (provider, stubber)
 
+    def _get_stubbed_fallback_auth_provider(self):
+        provider = Route53Provider('test')
+
+        # Use the stubber
+        stubber = Stubber(provider._conn)
+        stubber.activate()
+
+        return (provider, stubber)
+
+    def test_populate_with_fallback(self):
+        provider, stubber = self._get_stubbed_fallback_auth_provider()
+
+        got = Zone('unit.tests.', [])
+        with self.assertRaises(ClientError):
+            stubber.add_client_error('list_hosted_zones')
+            provider.populate(got)
+
     def test_populate(self):
         provider, stubber = self._get_stubbed_provider()