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-synapse-admin/defaults/main.yml

@@ -248,3 +248,13 @@ matrix_synapse_admin_config_asManagedUsers_custom: []  # noqa var-naming
 # Example for mautrix-telegram: ["^@telegram_[a-zA-Z0-9]+:example\\.com$"]
 # WARNING: you want to use matrix_synapse_admin_config_asManagedUsers_custom instead of this variable.
 matrix_synapse_admin_config_asManagedUsers: "{{ matrix_synapse_admin_config_asManagedUsers_auto + matrix_synapse_admin_config_asManagedUsers_custom }}"  # noqa var-naming
+
+# matrix_synapse_admin_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_synapse_admin_restart_necessary: false

roles/custom/matrix-synapse-admin/tasks/setup_install.yml

@@ -31,6 +31,7 @@
     owner: "{{ matrix_user_name }}"
     group: "{{ matrix_group_name }}"
     mode: 0640
+  register: matrix_synapse_admin_support_files_result
 
 - name: Ensure matrix-synapse-admin configuration installed
   ansible.builtin.copy:
@@ -39,6 +40,7 @@
     mode: 0644
     owner: "{{ matrix_user_name }}"
     group: "{{ matrix_group_name }}"
+  register: matrix_synapse_admin_config_result
 
 - name: Ensure matrix-synapse-admin image is pulled
   community.docker.docker_image:
@@ -47,10 +49,10 @@
     force_source: "{{ matrix_synapse_admin_docker_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_synapse_admin_docker_image_force_pull }}"
   when: not matrix_synapse_admin_container_image_self_build | bool
-  register: result
+  register: matrix_synapse_admin_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_synapse_admin_container_image_pull_result is not failed
 
 - name: Ensure matrix-synapse-admin repository is present when self-building
   ansible.builtin.git:
@@ -87,3 +89,14 @@
     src: "{{ role_path }}/templates/systemd/matrix-synapse-admin.service.j2"
     dest: "{{ devture_systemd_docker_base_systemd_path }}/matrix-synapse-admin.service"
     mode: 0644
+  register: matrix_synapse_admin_systemd_service_result
+
+- name: Determine whether Synapse Admin needs a restart
+  ansible.builtin.set_fact:
+    matrix_synapse_admin_restart_necessary: >-
+      {{
+        matrix_synapse_admin_support_files_result.changed | default(false)
+        or matrix_synapse_admin_config_result.changed | default(false)
+        or matrix_synapse_admin_systemd_service_result.changed | default(false)
+        or matrix_synapse_admin_container_image_pull_result.changed | default(false)
+      }}