Add matrix_homeserver_enabled variable

We need this to control whether `('matrix-' + matrix_homeserver_implementation + '.service')`
would get injected into `devture_systemd_service_manager_services_list_auto`

group_vars/matrix_servers

@@ -249,7 +249,7 @@ devture_systemd_service_manager_services_list_auto: |
     +
     ([{'name': 'matrix-client-hydrogen.service', 'priority': 2000, 'groups': ['matrix', 'clients', 'hydrogen']}] if matrix_client_hydrogen_enabled else [])
     +
-    ([{'name': ('matrix-' + matrix_homeserver_implementation + '.service'), 'priority': 1000, 'groups': ['matrix', 'homeservers', matrix_homeserver_implementation]}])
+    ([{'name': ('matrix-' + matrix_homeserver_implementation + '.service'), 'priority': 1000, 'groups': ['matrix', 'homeservers', matrix_homeserver_implementation]}] if matrix_homeserver_enabled else [])
     +
     ([{'name': 'matrix-corporal.service', 'priority': 1500, 'groups': ['matrix', 'corporal']}] if matrix_corporal_enabled else [])
     +

roles/custom/matrix-base/defaults/main.yml

@@ -1,4 +1,5 @@
 ---
+
 # The bare domain name which represents your Matrix identity.
 # Matrix user ids for your server will be of the form (`@user:<matrix-domain>`).
 #
@@ -12,6 +13,15 @@ matrix_domain: ~
 # Example value: "@someone:{{ matrix_domain }}"
 matrix_admin: ''
 
+# matrix_homeserver_enabled controls whether to enable the homeserver systemd service, etc.
+#
+# Unless you're wrapping this playbook in another one
+# where you optionally wish to disable homeserver integration, you don't need to use this.
+#
+# Note: disabling this does not mean that a homeserver won't get installed.
+# Whether homeserver software is installed depends on other (`matrix_HOMESERVER_enabled`) variables - see `group_vars/matrix_servers`.
+matrix_homeserver_enabled: true
+
 # Homeserver admin contacts and support page as per MSC 1929
 # See: https://github.com/matrix-org/matrix-spec-proposals/pull/1929
 # Users in form:

roles/custom/matrix-base/tasks/main.yml

@@ -1,6 +1,6 @@
 ---
 
-- ansible.builtin.import_tasks: "{{ role_path }}/tasks/sanity_check.yml"
+- ansible.builtin.import_tasks: "{{ role_path }}/tasks/validate_config.yml"
   tags:
     - setup-all