Do not allow handlers from dynamic includes to be notified (#78399)

* Do not allow handlers from dynamic includes to be notified

changelogs/fragments/dont-expose-included-handlers.yml

@@ -0,0 +1,2 @@
+bugfixes:
+  - Do not allow handlers from dynamic includes to be notified (https://github.com/ansible/ansible/pull/78399)

lib/ansible/plugins/strategy/__init__.py

@@ -1028,7 +1028,6 @@ class StrategyBase:
                     # for every task in each block brought in by the include, add the list
                     # of hosts which included the file to the notified_handlers dict
                     for block in new_blocks:
-                        iterator._play.handlers.append(block)
                         for task in block.block:
                             task_name = task.get_name()
                             display.debug("adding task '%s' included in handler '%s'" % (task_name, handler_name))

test/integration/targets/handlers/runme.sh

@@ -118,3 +118,8 @@ grep out.txt -e "\[WARNING\]: Handler 'handler name with {{ test_var }}' is unus
 # Test include_role and import_role cannot be used as handlers
 ansible-playbook test_role_as_handler.yml "$@"  2>&1 | tee out.txt
 grep out.txt -e "ERROR! Using 'include_role' as a handler is not supported."
+
+# Test notifying a handler from within include_tasks does not work anymore
+ansible-playbook test_notify_included.yml "$@"  2>&1 | tee out.txt
+[ "$(grep out.txt -ce 'I was included')" = "1" ]
+grep out.txt -e "ERROR! The requested handler 'handler_from_include' was not found in either the main handlers list nor in the listening handlers list"

test/integration/targets/handlers/test_notify_included-handlers.yml

@@ -0,0 +1,3 @@
+- name: handler_from_include
+  debug:
+    msg: I was included

test/integration/targets/handlers/test_notify_included.yml

@@ -0,0 +1,16 @@
+- name: This worked unintentionally, make sure it does not anymore
+  hosts: localhost
+  gather_facts: false
+  tasks:
+    - command: echo
+      notify:
+        - include_handler
+
+    - meta: flush_handlers
+
+    - command: echo
+      notify:
+        - handler_from_include
+  handlers:
+    - name: include_handler
+      include_tasks: test_notify_included-handlers.yml