Add automatic config for ext nginx, adjust docs

docs/configuring-playbook-bot-maubot.md

@@ -62,8 +62,20 @@ You can expand "Access token" to copy it.
 
 **IMPORTANT**: once you copy the token, just close the Matrix client window/tab. Do not "log out", as that would invalidate the token.
 
+## External nginx
 
+To use the management interface with an [external nginx webserver](configuring-playbook-own-webserver.md) the configuration will default to
+a http bind port at `127.0.0.1:29316`. If you need to use a different interface add the following to your `vars.yml` (e.g. with `0.0.0.0`).
 
+```yaml
+# Controls whether the maubot container exposes its HTTP management interface port (tcp/29316 in the container).
+#
+# Takes an "<ip>:<port>" or "<port>" value (e.g. "127.0.0.1:29316"), or empty string to not expose.
+# If you'll be setting this at all, it should be defined in terms of `matrix_bot_maubot_management_interface_port`.
+# Example:
+# matrix_bot_maubot_management_interface_http_bind_port: "127.0.0.1:{{ matrix_bot_maubot_management_interface_port }}"
+matrix_bot_maubot_management_interface_http_bind_port: '0.0.0.0:{{ matrix_bot_maubot_management_interface_port }}'
+```
 
 
 

group_vars/matrix_servers

@@ -1125,6 +1125,8 @@ matrix_bot_maubot_registration_shared_secret: |-
     }[matrix_homeserver_implementation]
   }}
 
+matrix_bot_maubot_management_interface_http_bind_port: "{{ '' if matrix_nginx_proxy_enabled else ('127.0.0.1:' + matrix_bot_maubot_management_interface_port | string) }}"
+
 # Postgres is the default, except if not using `matrix_postgres` (internal postgres)
 matrix_bot_maubot_database_engine: "{{ 'postgres' if matrix_postgres_enabled else 'sqlite' }}"
 matrix_bot_maubot_database_password: "{{ '%s' | format(matrix_homeserver_generic_secret_key) | password_hash('sha512', 'mxpup.dsc.db') | to_uuid }}"