[Develop] Get region from Identity Document instead of AZ (aws#2812)

* Fix an issue in the way we get region when manage volumes so that it can correctly handle local zone.

CHANGELOG.md

@@ -3,6 +3,14 @@ aws-parallelcluster-cookbook CHANGELOG
 
 This file is used to list changes made in each version of the AWS ParallelCluster cookbook.
 
+3.12.0
+------
+
+**CHANGES**
+
+**BUG FIXES**
+- Fix an issue in the way we get region when manage volumes so that it can correctly handle local zone.
+
 3.11.1
 ------
 

cookbooks/aws-parallelcluster-environment/files/default/ec2_udev_rules/manageVolume.py

@@ -214,8 +214,9 @@ def handle_volume(volume_id, attach, detach):
 
     instance_id = get_metadata_value(token, "http://169.254.169.254/latest/meta-data/instance-id")
 
-    region = get_metadata_value(token, "http://169.254.169.254/latest/meta-data/placement/availability-zone")
-    region = region[:-1]
+    identity_document = get_metadata_value(token, "http://169.254.169.254/latest/dynamic/instance-identity/document")
+    identity = json.loads(identity_document)
+    region = identity["region"]
 
     proxy_config = parse_proxy_config()