[2.7] docker_swarm_service: rename return variable to swarm_service (#53408)

* docker_swarm_service: rename return variable to swarm_service (#53229)

* Rename return variable to swarm_service.

* Add changelog.

* Add that old name will stay in Ansible 2.7.x.

(cherry picked from commit 61abbfc269)

* Keep old variable for backwards compatibility.

changelogs/fragments/53229-docker_swarm_service-return-value.yml

@@ -0,0 +1,5 @@
+bugfixes:
+- "docker_swarm_service - the return value was documented as ``ansible_swarm_service``, but the
+   module actually returned ``ansible_docker_service``. Documentation and code have been updated
+   so that the variable is now called ``swarm_service``. In Ansible 2.7.x, the old name
+   ``ansible_docker_service`` can still be used to access the result."

lib/ansible/modules/cloud/docker/docker_swarm_service.py

@@ -299,13 +299,17 @@ requirements:
 '''
 
 RETURN = '''
-ansible_swarm_service:
+swarm_service:
   returned: always
   type: dict
   description:
   - Dictionary of variables representing the current state of the service.
     Matches the module parameters format.
   - Note that facts are not part of registered vars but accessible directly.
+  - Note that before Ansible 2.7.9, the return variable was documented as C(ansible_swarm_service),
+    while the module actually returned a variable called C(ansible_docker_service). The variable
+    was renamed to C(swarm_service) in both code and documentation for Ansible 2.7.9 and Ansible 2.8.0.
+    In Ansible 2.7.x, the old name C(ansible_docker_service) can still be used.
   sample: '{
     "args": [
       "sleep",
@@ -1193,7 +1197,14 @@ def main():
     dsm = DockerServiceManager(client)
     msg, changed, rebuilt, changes, facts = dsm.run()
 
-    client.module.exit_json(msg=msg, changed=changed, rebuilt=rebuilt, changes=changes, ansible_docker_service=facts)
+    client.module.exit_json(
+        msg=msg,
+        changed=changed,
+        rebuilt=rebuilt,
+        changes=changes,
+        swarm_service=facts,
+        ansible_docker_service=facts  # kept for backwards-compatibility, will be removed in Ansible 2.8
+    )
 
 
 if __name__ == '__main__':