Add support for controlling Synapse's autocreate_auto_join_rooms

roles/matrix-server/defaults/main.yml

@@ -91,6 +91,10 @@ matrix_synapse_enable_registration: false
 # Rooms are to be specified using addresses (e.g. `#address:example.com`)
 matrix_synapse_auto_join_rooms: []
 
+# Controls whether auto-join rooms (`matrix_synapse_auto_join_rooms`) are to be created
+# automatically if they don't already exist.
+matrix_synapse_autocreate_auto_join_rooms: true
+
 # Controls password-peppering for Matrix Synapse. Not to be changed after initial setup.
 matrix_synapse_password_config_pepper: ""
 

roles/matrix-server/templates/synapse/homeserver.yaml.j2

@@ -488,7 +488,7 @@ auto_join_rooms:
 # homeserver registers.
 # Setting to false means that if the rooms are not manually created,
 # users cannot be auto-joined since they do not exist.
-autocreate_auto_join_rooms: true
+autocreate_auto_join_rooms: {{ matrix_synapse_autocreate_auto_join_rooms }}