Matrix

Matrix defines a set of open APIs for decentralised communication, suitable for securely publishing, persisting and subscribing to data over a global open federation of servers with no single point of control. Uses include Instant Messaging (IM), Voice over IP (VoIP) signalling, Internet of Things (IoT) communication, and bridging together existing communication silos - providing the basis of a new open real-time communication ecosystem.

This article extends the documentation in NixOS manual.

NixOS Matrix channels

https://matrix.to/#/#community:nixos.org

NixOS Matrix accounts for GitHub org members

https://discourse.nixos.org/t/matrix-account-hosting-for-nix-os-hackers/14036

Clients

Desktop clients

A few Matrix desktop clients are packaged for NixOS.

• Element (formerly Riot, based on Electron)
• Fractal
• gomuks
• neochat
• Mirage
• nheko
• Quaternion
• iamb

A Pidgin / libpurple plugin is also available.

Element

The config.json file used by Element can be configured as such:

nixpkgs.config.element-web.conf = {
  show_labs_settings = true;
  default_theme = "dark";
};

Web clients

There is also a web version of Element which can be served using a web server. See the NixOS manual entry.

Servers

Homeservers

Synapse

Currently, only the reference Matrix homeserver Synapse is packaged for NixOS. It has an associated module exposing the services.matrix-synapse.* options. See the NixOS manual entry for a complete configuration example.

Coturn with Synapse

For WebRTC calls to work when both callers are behind a NAT, you need to provide a turn server for clients to use. Here is an example configuration, inspired from this configuration file.

{config, pkgs, lib, ...}: {
  # enable coturn
  services.coturn = rec {
    enable = true;
    no-cli = true;
    no-tcp-relay = true;
    min-port = 49000;
    max-port = 50000;
    use-auth-secret = true;
    static-auth-secret = "will be world readable for local users :(";
    realm = "turn.example.com";
    cert = "${config.security.acme.certs.${realm}.directory}/full.pem";
    pkey = "${config.security.acme.certs.${realm}.directory}/key.pem";
    extraConfig = ''
      # for debugging
      verbose
      # ban private IP ranges
      no-multicast-peers
      denied-peer-ip=0.0.0.0-0.255.255.255
      denied-peer-ip=10.0.0.0-10.255.255.255
      denied-peer-ip=100.64.0.0-100.127.255.255
      denied-peer-ip=127.0.0.0-127.255.255.255
      denied-peer-ip=169.254.0.0-169.254.255.255
      denied-peer-ip=172.16.0.0-172.31.255.255
      denied-peer-ip=192.0.0.0-192.0.0.255
      denied-peer-ip=192.0.2.0-192.0.2.255
      denied-peer-ip=192.88.99.0-192.88.99.255
      denied-peer-ip=192.168.0.0-192.168.255.255
      denied-peer-ip=198.18.0.0-198.19.255.255
      denied-peer-ip=198.51.100.0-198.51.100.255
      denied-peer-ip=203.0.113.0-203.0.113.255
      denied-peer-ip=240.0.0.0-255.255.255.255
      denied-peer-ip=::1
      denied-peer-ip=64:ff9b::-64:ff9b::ffff:ffff
      denied-peer-ip=::ffff:0.0.0.0-::ffff:255.255.255.255
      denied-peer-ip=100::-100::ffff:ffff:ffff:ffff
      denied-peer-ip=2001::-2001:1ff:ffff:ffff:ffff:ffff:ffff:ffff
      denied-peer-ip=2002::-2002:ffff:ffff:ffff:ffff:ffff:ffff:ffff
      denied-peer-ip=fc00::-fdff:ffff:ffff:ffff:ffff:ffff:ffff:ffff
      denied-peer-ip=fe80::-febf:ffff:ffff:ffff:ffff:ffff:ffff:ffff
    '';
  };
  # open the firewall
  networking.firewall = {
    interfaces.enp2s0 = let
      range = with config.services.coturn; lib.singleton {
        from = min-port;
        to = max-port;
      };
    in
    {
      allowedUDPPortRanges = range;
      allowedUDPPorts = [ 3478 5349 ];
      allowedTCPPortRanges = [ ];
      allowedTCPPorts = [ 3478 5349 ];
    };
  };
  # get a certificate
  security.acme.certs.${config.services.coturn.realm} = {
    /* insert here the right configuration to obtain a certificate */
    postRun = "systemctl restart coturn.service";
    group = "turnserver";
  };
  # configure synapse to point users to coturn
  services.matrix-synapse.settings = with config.services.coturn; {
    turn_uris = ["turn:${realm}:3478?transport=udp" "turn:${realm}:3478?transport=tcp"];
    turn_shared_secret = static-auth-secret;
    turn_user_lifetime = "1h";
  };
}

Synapse with Workers

There's an external module to automatically set up synapse and configure nginx with workers: https://github.com/dali99/nixos-matrix-modules

Application services (a.k.a. bridges)

Bridges allow you to connect Matrix to a third-party platform (like Discord, Telegram, etc.), and interact seamlessly. See here for a list of currently supported bridges.

mautrix-telegram

Full configuration reference: https://github.com/tulir/mautrix-telegram/blob/master/mautrix_telegram/example-config.yaml

Example NixOS config:

{
  services.matrix-synapse = {
    enable = true;
    settings.app_service_config_files = [
      # The registration file is automatically generated after starting the
      # appservice for the first time.
      # cp /var/lib/mautrix-telegram/telegram-registration.yaml \
      #   /var/lib/matrix-synapse/
      # chown matrix-synapse:matrix-synapse \
      #   /var/lib/matrix-synapse/telegram-registration.yaml
      "/var/lib/matrix-synapse/telegram-registration.yaml"
    ];
    # ...
  };

  services.mautrix-telegram = {
    enable = true;

    # file containing the appservice and telegram tokens
    environmentFile = "/etc/secrets/mautrix-telegram.env";

    # The appservice is pre-configured to use SQLite by default.
    # It's also possible to use PostgreSQL.
    settings = {
      homeserver = {
        address = "http://localhost:8008";
        domain = "domain.tld";
      };
      appservice = {
        provisioning.enabled = false;
        id = "telegram";
        public = {
          enabled = true;
          prefix = "/public";
          external = "http://domain.tld:8080/public";
        };

        # The service uses SQLite by default, but it's also possible to use
        # PostgreSQL instead:
        #database = "postgresql:///mautrix-telegram?host=/run/postgresql";
      };
      bridge = {
        relaybot.authless_portals = false;
        permissions = {
          "@someadmin:domain.tld" = "admin";
        };

        # Animated stickers conversion requires additional packages in the
        # service's path.
        # If this isn't a fresh installation, clearing the bridge's uploaded
        # file cache might be necessary (make a database backup first!):
        # delete from telegram_file where \
        #   mime_type in ('application/gzip', 'application/octet-stream')
        animated_sticker = {
          target = "gif";
          args = {
            width = 256;
            height = 256;
            fps = 30;               # only for webm
            background = "020202";  # only for gif, transparency not supported
          };
        };
      };
    };
  };

  systemd.services.mautrix-telegram.path = with pkgs; [
    lottieconverter  # for animated stickers conversion, unfree package
    ffmpeg           # if converting animated stickers to webm (very slow!)
  ];
}

mautrix-whatsapp

Packaged as mautrix-whatsapp. Module implemented in this PR.

matrix-appservice-irc

NixOS-specific module options: TODO link to the search results once it's landed

Full configuration reference: https://github.com/matrix-org/matrix-appservice-irc/blob/develop/config.sample.yaml

Upstream documentation: https://matrix-org.github.io/matrix-appservice-irc/latest/introduction.html

Example configuration:

services.matrix-appservice-irc = {
  enable = true;
  registrationUrl = "https://ircbridge.mydomain.com"; # Or localhost

  # Everything from here is passed to the appservice
  settings = {
    homeserver.url = "https://matrix.mydomain.com"; # Or localhost
    homeserver.domain = "mydomain.com";

    # Bridge settings for Freenode. You can bridge multiple services.
    ircService.servers."chat.freenode.net" = {
      name = "freenode";
      port = 6697;
      ssl = true;
      dynamicChannels = {
        enabled = true;
        aliasTemplate = "#irc_$CHANNEL";
        groupId = "+irc:localhost";
      };
      matrixClients = {
        userTemplate = "@irc_$NICK";
      };
      ircClients = {
        nickTemplate = "$LOCALPART[m]";
        allowNickChanges = true;
      };

      membershipLists = {
        enabled = true;
        global = {
          ircToMatrix = {
            initial = true;
            incremental = true;
          };
          matrixToIrc = {
            initial = true;
            incremental = true;
          };
        };
      };
    };
  };
};

This example configuration creates a bridge for only one IRC network, Freenode. Some options are set to make an example, but you absolutely *should* read the whole configuration documentation and set all options you want before starting. The example options show you how to adapt the room/user name space template for the use case where you only have one IRC server bridged, and also enables increased membership sync because it is disabled on the official Freenode bridge.

The appservice automatically creates a registration file under /var/lib/matrix-appservice-irc/registration.yml and keeps it up to date. If your homeserver is not located on the same machine and NixOS installation, you must absolutely make sure to synchronize that file over to the home server after each modification and keep both in sync.

matrix-appservice-discord

Full configuration reference: https://github.com/Half-Shot/matrix-appservice-discord/blob/master/config/config.sample.yaml

Example NixOS config:

{
  services.matrix-synapse = {
    enable = true;
    app_service_config_files = [
      # The registration file is automatically generated after starting the
      # appservice for the first time.
      # cp /var/lib/matrix-appservice-discord/discord-registration.yaml \
      #   /var/lib/matrix-synapse/
      # chown matrix-synapse:matrix-synapse \
      #   /var/lib/matrix-synapse/discord-registration.yaml
      "/var/lib/matrix-synapse/discord-registration.yaml"
    ];
    # ...
  };

  services.matrix-appservice-discord = {
    enable = true;
    environmentFile = /etc/keyring/matrix-appservice-discord/tokens.env;
    # The appservice is pre-configured to use SQLite by default.
    # It's also possible to use PostgreSQL.
    settings = {
      bridge = {
        domain = "test.tld";
        homeserverUrl = "https://public.endpoint.test.tld";
      };

      # The service uses SQLite by default, but it's also possible to use
      # PostgreSQL instead:
      #database = {
      #  filename = ""; # empty value to disable sqlite
      #  connString = "socket:/run/postgresql?db=matrix-appservice-discord";
      #};
    };
  };
}

See also

• Mjolnir - a Matrix moderation tool
• The Nix Matrix Subsystem chat room, on Matrix