nixos/matrix-synapse: add UNIX domain socket listener support

Exposes two options, `path` and `mode`, to configure the location and
permissions on the socket file.

The `mode` needs to be specified as string in octal and will be converted
into a decimal integer, so it correctly passes through the YAML parser
and arrives at the `os.chmod` call in the Twisted codebase. What a fun
detour.

Adds an assertion, that either `path` or `bind_addresses` and `port` are
configured on every listener.

Migrates the default replication listener of the main instance to a UNIX
domain socket, because it is more efficient.

Introduces the `enableRegistrationScript` option, to gracefully disable
the user registration script, when the client listener listens on a UNIX
domain socket, which is something the script does not support.

1 files changed, 3 insertions, 0 deletions

diff --git a/nixos/doc/manual/release-notes/rl-2405.section.md b/nixos/doc/manual/release-notes/rl-2405.section.md
index d3efc1789cdc..bbe59b002003 100644
--- a/nixos/doc/manual/release-notes/rl-2405.section.md
+++ b/nixos/doc/manual/release-notes/rl-2405.section.md
@@ -246,6 +246,9 @@ The pre-existing [services.ankisyncd](#opt-services.ankisyncd.enable) has been m
 - `services.postgresql.extraPlugins` changed its type from just a list of packages to also a function that returns such a list.
   For example a config line like ``services.postgresql.extraPlugins = with pkgs.postgresql_11.pkgs; [ postgis ];`` is recommended to be changed to ``services.postgresql.extraPlugins = ps: with ps; [ postgis ];``;
 
+- The Matrix homeserver [Synapse](https://element-hq.github.io/synapse/) module now supports configuring UNIX domain socket [listeners](#opt-services.matrix-synapse.settings.listeners) through the `path` option.
+  The default replication worker on the main instance has been migrated away from TCP sockets to UNIX domain sockets.
+
 - Programs written in [Nim](https://nim-lang.org/) are built with libraries selected by lockfiles.
   The `nimPackages` and `nim2Packages` sets have been removed.
   See https://nixos.org/manual/nixpkgs/unstable#nim for more information.