docker_swarm: add diff support (#52947)

* Add diff support to docker_swarm.

* Add changelog.

* Using diff mode for docker_swarm tests. This improves debugging, since the the module now outputs more information on *why* it did certain actions.

changelogs/fragments/52947-docker_swarm-diff.yaml

@@ -0,0 +1,2 @@
+minor_changes:
+- "docker_swarm - module now supports ``--diff`` mode."

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

@@ -391,6 +391,11 @@ class SwarmManager(DockerBaseClass):
 
         choice_map.get(self.state)()
 
+        if self.client.module._diff or self.parameters.debug:
+            diff = dict()
+            diff['before'], diff['after'] = self.differences.get_before_after()
+            self.results['diff'] = diff
+
     def __isSwarmManager(self):
         try:
             data = self.client.inspect_swarm()

test/integration/targets/docker_swarm/tasks/test_swarm.yml

@@ -4,6 +4,7 @@
     docker_swarm:
       state: absent
       force: true
+    diff: no
 
   - name: Test parameters with state=join
     docker_swarm:
@@ -34,18 +35,21 @@
       state: present
       advertise_addr: "{{ansible_default_ipv4.address}}"
     check_mode: yes
+    diff: yes
     register: output_1
 
   - name: Create a Swarm cluster
     docker_swarm:
       state: present
       advertise_addr: "{{ansible_default_ipv4.address}}"
+    diff: yes
     register: output_2
 
   - name: Create a Swarm cluster (idempotent)
     docker_swarm:
       state: present
       advertise_addr: "{{ansible_default_ipv4.address}}"
+    diff: yes
     register: output_3
 
   - name: Create a Swarm cluster (idempotent, check mode)
@@ -53,36 +57,48 @@
       state: present
       advertise_addr: "{{ansible_default_ipv4.address}}"
     check_mode: yes
+    diff: yes
     register: output_4
 
   - name: assert changed when create a new swarm cluster
     assert:
       that:
          - 'output_1 is changed'
+         - 'output_1.diff.before is defined'
+         - 'output_1.diff.after is defined'
          - 'output_2 is changed'
          - 'output_2.actions[0] | regex_search("New Swarm cluster created: ")'
          - 'output_2.swarm_facts.JoinTokens.Manager'
          - 'output_2.swarm_facts.JoinTokens.Worker'
+         - 'output_2.diff.before is defined'
+         - 'output_2.diff.after is defined'
          - 'output_3 is not changed'
+         - 'output_3.diff.before is defined'
+         - 'output_3.diff.after is defined'
          - 'output_4 is not changed'
+         - 'output_4.diff.before is defined'
+         - 'output_4.diff.after is defined'
 
   - name: Remove a Swarm cluster (check mode)
     docker_swarm:
       state: absent
       force: true
     check_mode: yes
+    diff: yes
     register: output_1
 
   - name: Remove a Swarm cluster
     docker_swarm:
       state: absent
       force: true
+    diff: yes
     register: output_2
 
   - name: Remove a Swarm cluster (idempotent)
     docker_swarm:
       state: absent
       force: true
+    diff: yes
     register: output_3
 
   - name: Remove a Swarm cluster (idempotent, check mode)
@@ -90,19 +106,29 @@
       state: absent
       force: true
     check_mode: yes
+    diff: yes
     register: output_4
 
   - name: assert changed when remove a swarm cluster
     assert:
       that:
          - 'output_1 is changed'
+         - 'output_1.diff.before is defined'
+         - 'output_1.diff.after is defined'
          - 'output_2 is changed'
          - 'output_2.actions[0] == "Node has left the swarm cluster"'
+         - 'output_2.diff.before is defined'
+         - 'output_2.diff.after is defined'
          - 'output_3 is not changed'
+         - 'output_3.diff.before is defined'
+         - 'output_3.diff.after is defined'
          - 'output_4 is not changed'
+         - 'output_4.diff.before is defined'
+         - 'output_4.diff.after is defined'
 
   always:
   - name: Cleanup
     docker_swarm:
       state: absent
       force: true
+    diff: no