ec2_vol: preset the name tag of the volume

Closes: ansible-collections#229

changelogs/fragments/242_ec2_vol-preset-the-name-tag-of-the-volume.yaml

@@ -0,0 +1,3 @@
+---
+bugfixes:
+- ec2_vol - create or update now preserves the existing tags, including Name (https://github.com/ansible-collections/amazon.aws/issues/229) 

plugins/modules/ec2_vol.py

@@ -781,7 +781,8 @@ def main():
         else:
             volume, changed = create_volume(module, ec2_conn, zone=zone)
 
-        tags['Name'] = name
+        if name:
+            tags['Name'] = name
         final_tags, tags_changed = ensure_tags(module, ec2_conn, volume['volume_id'], 'volume', tags, False)
 
         if detach_vol_flag:

tests/integration/targets/ec2_vol/tasks/tests.yml

@@ -74,6 +74,7 @@
           - "'attachment_set' in volume1.volume"
           - "'instance_id' in volume1.volume.attachment_set"
           - not volume1.volume.attachment_set.instance_id
+          - not ("Name" in volume1.volume.tags)
           - not volume1.volume.encrypted
 
     # no idempotency check needed here
@@ -102,6 +103,7 @@
           - volume2.volume_type == 'io1'
           - volume2.volume.iops == 101
           - volume2.volume.size == 4
+          - volume2.volume.tags.Name == "{{ resource_prefix }}" 
           - volume2.volume.encrypted
 
     - name: create another volume (override module defaults) (idempotent)