Add tasks_only callback (#10347)

* Add tasks_only callback.

* Improve tests.

* Fix option name.

* Add missing s.

Co-authored-by: Alexei Znamensky <103110+russoz@users.noreply.github.com>

* Add ignore.txt entry.

---------

Co-authored-by: Alexei Znamensky <103110+russoz@users.noreply.github.com>

plugins/callback/tasks_only.py

@@ -0,0 +1,62 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2025, Felix Fontein <felix@fontein.de>
+# GNU General Public License v3.0+ (see LICENSES/GPL-3.0-or-later.txt or https://www.gnu.org/licenses/gpl-3.0.txt)
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+from __future__ import annotations
+
+DOCUMENTATION = r"""
+author: Felix Fontein (@felixfontein)
+name: tasks_only
+type: stdout
+version_added: 11.1.0
+short_description: Only show tasks
+description:
+  - Removes play start and stats marker from P(ansible.builtin.default#callback)'s output.
+  - Can be used to generate output for documentation examples.
+    For this, the O(number_of_columns) option should be set to an explicit value.
+extends_documentation_fragment:
+  - default_callback
+options:
+  number_of_columns:
+    description:
+      - Sets the number of columns for Ansible's display.
+    type: int
+    env:
+      - name: ANSIBLE_COLLECTIONS_TASKS_ONLY_NUMBER_OF_COLUMNS
+"""
+
+EXAMPLES = r"""
+---
+# Enable callback in ansible.cfg:
+ansible_config: |-
+  [defaults]
+  stdout_callback = community.general.tasks_only
+
+---
+# Enable callback with environment variables:
+environment_variable: |-
+  ANSIBLE_STDOUT_CALLBACK=community.general.tasks_only
+"""
+
+from ansible.plugins.callback.default import CallbackModule as Default
+
+
+class CallbackModule(Default):
+    CALLBACK_VERSION = 2.0
+    CALLBACK_TYPE = 'stdout'
+    CALLBACK_NAME = 'community.general.tasks_only'
+
+    def v2_playbook_on_play_start(self, play):
+        pass
+
+    def v2_playbook_on_stats(self, stats):
+        pass
+
+    def set_options(self, *args, **kwargs):
+        result = super(CallbackModule, self).set_options(*args, **kwargs)
+        self.number_of_columns = self.get_option("number_of_columns")
+        if self.number_of_columns is not None:
+            self._display.columns = self.number_of_columns
+        return result