Fix zone value in monitored resource (census-instrumentation#534)

Author: colincadams

opencensus/common/monitored_resource/gcp_metadata_config.py

@@ -37,6 +37,10 @@
     ZONE_KEY: 'instance/zone'
 }
 
+_ATTRIBUTE_URI_TRANSFORMATIONS = {
+    _GCE_ATTRIBUTES[ZONE_KEY]:
+        lambda v: v[v.rfind('/') + 1:] if '/' in v else v
+}
 
 _GCP_METADATA_MAP = {}
 
@@ -104,4 +108,8 @@ def get_attribute(attribute_uri):
             # to a normal string:
             attribute_value = attribute_value.decode('utf-8')
 
+        transformation = _ATTRIBUTE_URI_TRANSFORMATIONS.get(attribute_uri)
+        if transformation is not None:
+            attribute_value = transformation(attribute_value)
+
         return attribute_value

tests/unit/common/monitored_resource_util/test_gcp_metadata_config.py

@@ -31,7 +31,7 @@ def assign_attribute_value(*args, **kwargs):
             elif attribute_uri == 'project-id':
                 return 'my-project'
             elif attribute_uri == 'zone':
-                return 'us-east1'
+                return '/projects/012345678/zones/us-east1'
 
         http_request_mock.side_effect = assign_attribute_value
         gcp_metadata_config.GcpMetadataConfig.inited = False
@@ -68,7 +68,7 @@ def assign_attribute_value(*args, **kwargs):
             elif attribute_uri == 'project-id':
                 return b'my-project'
             elif attribute_uri == 'zone':
-                return b'us-east1'
+                return b'/projects/012345678/zones/us-east1'
 
         http_request_mock.side_effect = assign_attribute_value
         gcp_metadata_config.GcpMetadataConfig.inited = False