wip: ansible pull

Also use this role instead of plain ansible.builtin.reboot.
This is in preparation for using ansible_pull as we don't want to have
ansible.builtin.reboot fail local playbook runs.

roles/apt_update_and_upgrade/handlers/main.yaml

@@ -1,6 +1,5 @@
 - name: reboot the system
-  ansible.builtin.import_role:
-    role: reboot
+  ansible.builtin.include_tasks: "../../reboot/tasks/main.yaml"
   vars:
     # Simply don't reboot on local connections and rely on proper handling of /var/run/reboot-required.
     reboot__local_handling: ignore

roles/reboot/README.md

@@ -10,3 +10,17 @@ A role for rebooting a host, which also handles local connections gracefully.
   - `ignore`: Just doesn't reboot on local connections.
   - `file`: Doesn't reboot on local connections and instead touches the file defined by `reboot__local_handling_file`.
 - `reboot__local_handling_file`: The file to touch, if `reboot__local_handling` is `file`. Defaults to `/var/run/ansible-reboot-required`.
+
+## Usage in a Handler
+
+Since a reboot should often be triggered from a handler and since handlers can't include or import roles, this roles logic can also be run by including the `main.yaml` task using `ansible.builtin.include_tasks` as a workaround.  
+When doing so, arguments should be specified explicitly as necessary (so at least `reboot__local_handling`) as the default role inclusion mechanisms like setting default values don't work.
+
+An example handler would look like this:
+
+```yaml
+- name: reboot the system
+  ansible.builtin.include_tasks: "../../reboot/tasks/main.yaml"
+  vars:
+    reboot__local_handling: ignore
+```