docker_compose: fix idempotency for stopped services (#159)

* Always use |= instead of = when updating changed status.

* Fix idempotence bug.

* Add changelog fragment.

changelogs/fragments/159-docker_compose-idempotence-fix.yml

@@ -0,0 +1,2 @@
+bugfixes:
+- "docker_compose - fix idempotence bug when using ``stopped: true`` (https://github.com/ansible-collections/community.docker/issues/142, https://github.com/ansible-collections/community.docker/pull/159)."

plugins/modules/docker_compose.py

@@ -730,12 +730,12 @@ class ContainerManager(DockerBaseClass):
 
         if self.pull:
             pull_output = self.cmd_pull()
-            result['changed'] = pull_output['changed']
+            result['changed'] |= pull_output['changed']
             result['actions'] += pull_output['actions']
 
         if self.build:
             build_output = self.cmd_build()
-            result['changed'] = build_output['changed']
+            result['changed'] |= build_output['changed']
             result['actions'] += build_output['actions']
 
         if self.remove_orphans:
@@ -760,6 +760,10 @@ class ContainerManager(DockerBaseClass):
         for service in self.project.services:
             if not service_names or service.name in service_names:
                 plan = service.convergence_plan(strategy=converge)
+                if plan.action == 'start' and self.stopped:
+                    # In case the only action is starting, and the user requested
+                    # that the service should be stopped, ignore this service.
+                    continue
                 if plan.action != 'noop':
                     result['changed'] = True
                     result_action = dict(service=service.name)
@@ -802,12 +806,12 @@ class ContainerManager(DockerBaseClass):
 
         if self.restarted:
             restart_output = self.cmd_restart(service_names)
-            result['changed'] = restart_output['changed']
+            result['changed'] |= restart_output['changed']
             result['actions'] += restart_output['actions']
 
         if self.scale:
             scale_output = self.cmd_scale()
-            result['changed'] = scale_output['changed']
+            result['changed'] |= scale_output['changed']
             result['actions'] += scale_output['actions']
 
         for service in self.project.services:

tests/integration/targets/docker_compose/tasks/tests/start-stop.yml

@@ -219,8 +219,8 @@
     that:
     - present_1 is changed
     - present_2 is changed
-    # - present_3 is not changed  -- FIXME! https://github.com/ansible-collections/community.docker/issues/142
-    # - present_4 is not changed  -- FIXME! https://github.com/ansible-collections/community.docker/issues/142
+    - present_3 is not changed
+    - present_4 is not changed
     - started_1 is changed
     - started_2 is changed
     - started_3 is not changed