Add conditional restart support to service roles

Track config/image/systemd changes via register: directives and compute
a _restart_necessary variable for each service role, allowing the
systemd_service_manager to skip unnecessary restarts during install-* runs.

Covers 22 service roles: alertmanager-receiver, appservice-draupnir-for-all,
bridge-mautrix-wsproxy (+ syncproxy), cactus-comments, cactus-comments-client,
corporal, element-admin, ldap-registration-proxy, livekit-jwt-service, matrixto,
pantalaimon, prometheus-nginxlog-exporter, rageshake, registration, static-files,
sygnal, synapse-admin, synapse-auto-compressor, synapse-reverse-proxy-companion,
synapse-usage-exporter, and user-verification-service.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

roles/custom/matrix-static-files/defaults/main.yml

@@ -404,3 +404,13 @@ matrix_static_files_self_check_hostname_identity: ''
 # As per the spec (https://matrix.org/docs/spec/client_server/r0.6.0#well-known-uri), it shouldn't be,
 # so we default to not following redirects as well.
 matrix_static_files_self_check_well_known_matrix_client_follow_redirects: none
+
+# matrix_static_files_restart_necessary controls whether the service
+# will be restarted (when true) or merely started (when false) by the
+# systemd service manager role (when conditional restart is enabled).
+#
+# This value is automatically computed during installation based on whether
+# any configuration files, the systemd service file, or the container image changed.
+# The default of `false` means "no restart needed" — appropriate when the role's
+# installation tasks haven't run (e.g., due to --tags skipping them).
+matrix_static_files_restart_necessary: false

roles/custom/matrix-static-files/tasks/install.yml

@@ -42,6 +42,7 @@
 
     - src: "{{ role_path }}/templates/labels.j2"
       dest: "{{ matrix_static_files_base_path }}/labels"
+  register: matrix_static_files_config_result
 
 - name: Ensure matrix-static-files files are installed
   ansible.builtin.copy:
@@ -69,6 +70,7 @@
     - content: "{{ matrix_static_files_file_index_html_template }}"
       dest: "{{ matrix_static_files_public_path }}/index.html"
       when: "{{ matrix_static_files_file_index_html_enabled }}"
+  register: matrix_static_files_files_result
 
 - name: Ensure /.well-known/matrix/server file deleted if not enabled
   ansible.builtin.file:
@@ -88,10 +90,10 @@
     source: "{{ 'pull' if ansible_version.major > 2 or ansible_version.minor > 7 else omit }}"
     force_source: "{{ matrix_static_files_container_image_force_pull if ansible_version.major > 2 or ansible_version.minor >= 8 else omit }}"
     force: "{{ omit if ansible_version.major > 2 or ansible_version.minor >= 8 else matrix_static_files_container_image_force_pull }}"
-  register: result
+  register: matrix_static_files_container_image_pull_result
   retries: "{{ devture_playbook_help_container_retries_count }}"
   delay: "{{ devture_playbook_help_container_retries_delay }}"
-  until: result is not failed
+  until: matrix_static_files_container_image_pull_result is not failed
 
 - name: Ensure matrix-static-files container network is created
   community.general.docker_network:
@@ -105,3 +107,14 @@
     src: "{{ role_path }}/templates/systemd/matrix-static-files.service.j2"
     dest: "{{ devture_systemd_docker_base_systemd_path }}/{{ matrix_static_files_identifier }}.service"
     mode: 0644
+  register: matrix_static_files_systemd_service_result
+
+- name: Determine whether matrix-static-files needs a restart
+  ansible.builtin.set_fact:
+    matrix_static_files_restart_necessary: >-
+      {{
+        matrix_static_files_config_result.changed | default(false)
+        or matrix_static_files_files_result.changed | default(false)
+        or matrix_static_files_systemd_service_result.changed | default(false)
+        or matrix_static_files_container_image_pull_result.changed | default(false)
+      }}