<chapter xmlns="http://docbook.org/ns/docbook"
         xmlns:xlink="http://www.w3.org/1999/xlink"
         xmlns:xi="http://www.w3.org/2001/XInclude"
         version="5.0"
         xml:id="module-services-matrix">
 <title>Matrix</title>
 <para>
  <link xlink:href="https://matrix.org/">Matrix</link> is an open standard for
  interoperable, decentralised, real-time communication over IP. It can be used
  to power Instant Messaging, VoIP/WebRTC signalling, Internet of Things
  communication - or anywhere you need a standard HTTP API for publishing and
  subscribing to data whilst tracking the conversation history.
 </para>
 <para>
  This chapter will show you how to set up your own, self-hosted Matrix
  homeserver using the Synapse reference homeserver, and how to serve your own
  copy of the Element web client. See the
  <link xlink:href="https://matrix.org/docs/projects/try-matrix-now.html">Try
  Matrix Now!</link> overview page for links to Element Apps for Android and iOS,
  desktop clients, as well as bridges to other networks and other projects
  around Matrix.
 </para>
 <section xml:id="module-services-matrix-synapse">
  <title>Synapse Homeserver</title>

  <para>
   <link xlink:href="https://github.com/matrix-org/synapse">Synapse</link> is
   the reference homeserver implementation of Matrix from the core development
   team at matrix.org. The following configuration example will set up a
   synapse server for the <literal>example.org</literal> domain, served from
   the host <literal>myhostname.example.org</literal>. For more information,
   please refer to the
   <link xlink:href="https://matrix-org.github.io/synapse/latest/setup/installation.html">
   installation instructions of Synapse </link>.
<programlisting>
{ pkgs, lib, config, ... }:
let
  fqdn = "${config.networking.hostName}.${config.networking.domain}";
  clientConfig = {
    "m.homeserver".base_url = "https://${fqdn}";
    "m.identity_server" = {};
  };
  serverConfig."m.server" = "${config.services.matrix-synapse.settings.server_name}:443";
  mkWellKnown = data: ''
    add_header Content-Type application/json;
    add_header Access-Control-Allow-Origin *;
    return 200 '${builtins.toJSON data}';
  '';
in {
  <xref linkend="opt-networking.hostName" /> = "myhostname";
  <xref linkend="opt-networking.domain" /> = "example.org";
  <xref linkend="opt-networking.firewall.allowedTCPPorts" /> = [ 80 443 ];

  <xref linkend="opt-services.postgresql.enable" /> = true;
  <xref linkend="opt-services.postgresql.initialScript" /> = pkgs.writeText "synapse-init.sql" ''
    CREATE ROLE "matrix-synapse" WITH LOGIN PASSWORD 'synapse';
    CREATE DATABASE "matrix-synapse" WITH OWNER "matrix-synapse"
      TEMPLATE template0
      LC_COLLATE = "C"
      LC_CTYPE = "C";
  '';

  services.nginx = {
    <link linkend="opt-services.nginx.enable">enable</link> = true;
    <link linkend="opt-services.nginx.recommendedTlsSettings">recommendedTlsSettings</link> = true;
    <link linkend="opt-services.nginx.recommendedOptimisation">recommendedOptimisation</link> = true;
    <link linkend="opt-services.nginx.recommendedGzipSettings">recommendedGzipSettings</link> = true;
    <link linkend="opt-services.nginx.recommendedProxySettings">recommendedProxySettings</link> = true;
    <link linkend="opt-services.nginx.virtualHosts">virtualHosts</link> = {
      "${config.networking.domain}" = { <co xml:id='ex-matrix-synapse-dns' />
        <link linkend="opt-services.nginx.virtualHosts._name_.enableACME">enableACME</link> = true;
        <link linkend="opt-services.nginx.virtualHosts._name_.forceSSL">forceSSL</link> = true;
        <link linkend="opt-services.nginx.virtualHosts._name_.locations._name_.extraConfig">locations."= /.well-known/matrix/server".extraConfig</link> = mkWellKnown serverConfig; <co xml:id='ex-matrix-synapse-well-known-server' />
        <link linkend="opt-services.nginx.virtualHosts._name_.locations._name_.extraConfig">locations."= /.well-known/matrix/client".extraConfig</link> = mkWellKnown clientConfig; <co xml:id='ex-matrix-synapse-well-known-client' />
      };
      "${fqdn}" = {
        <link linkend="opt-services.nginx.virtualHosts._name_.enableACME">enableACME</link> = true;
        <link linkend="opt-services.nginx.virtualHosts._name_.forceSSL">forceSSL</link> = true;
        <link linkend="opt-services.nginx.virtualHosts._name_.locations._name_.extraConfig">locations."/".extraConfig</link> = '' <co xml:id='ex-matrix-synapse-rev-default' />
          return 404;
        '';
        <link linkend="opt-services.nginx.virtualHosts._name_.locations._name_.proxyPass">locations."/_matrix".proxyPass</link> = "http://[::1]:8008"; <co xml:id='ex-matrix-synapse-rev-proxy-pass' />
        <link linkend="opt-services.nginx.virtualHosts._name_.locations._name_.proxyPass">locations."/_synapse/client".proxyPass</link> = "http://[::1]:8008"; <co xml:id='ex-matrix-synapse-rev-client' />
      };
    };
  };

  services.matrix-synapse = {
    <link linkend="opt-services.matrix-synapse.enable">enable</link> = true;
    <link linkend="opt-services.matrix-synapse.settings.server_name">settings.server_name</link> = config.networking.domain;
    <link linkend="opt-services.matrix-synapse.settings.listeners">settings.listeners</link> = [
      { <link linkend="opt-services.matrix-synapse.settings.listeners._.port">port</link> = 8008;
        <link linkend="opt-services.matrix-synapse.settings.listeners._.bind_addresses">bind_addresses</link> = [ "::1" ];
        <link linkend="opt-services.matrix-synapse.settings.listeners._.type">type</link> = "http";
        <link linkend="opt-services.matrix-synapse.settings.listeners._.tls">tls</link> = false;
        <link linkend="opt-services.matrix-synapse.settings.listeners._.x_forwarded">x_forwarded</link> = true;
        <link linkend="opt-services.matrix-synapse.settings.listeners._.resources">resources</link> = [ {
          <link linkend="opt-services.matrix-synapse.settings.listeners._.resources._.names">names</link> = [ "client" "federation" ];
          <link linkend="opt-services.matrix-synapse.settings.listeners._.resources._.compress">compress</link> = true;
        } ];
      }
    ];
  };
}
</programlisting>
  </para>
  <calloutlist>
   <callout arearefs='ex-matrix-synapse-dns'>
    <para>
     If the <code>A</code> and <code>AAAA</code> DNS records on
     <literal>example.org</literal> do not point on the same host as the records
     for <code>myhostname.example.org</code>, you can easily move the
     <code>/.well-known</code> virtualHost section of the code to the host that
     is serving <literal>example.org</literal>, while the rest stays on
     <literal>myhostname.example.org</literal> with no other changes required.
     This pattern also allows to seamlessly move the homeserver from
     <literal>myhostname.example.org</literal> to
     <literal>myotherhost.example.org</literal> by only changing the
     <code>/.well-known</code> redirection target.
    </para>
   </callout>
   <callout arearefs='ex-matrix-synapse-well-known-server'>
    <para>
     This section is not needed if the <link linkend="opt-services.matrix-synapse.settings.server_name">server_name</link>
     of <package>matrix-synapse</package> is equal to the domain (i.e.
     <literal>example.org</literal> from <literal>@foo:example.org</literal>)
     and the federation port is 8448.
     Further reference can be found in the <link xlink:href="https://matrix-org.github.io/synapse/latest/delegate.html">docs
     about delegation</link>.
    </para>
   </callout>
   <callout arearefs='ex-matrix-synapse-well-known-client'>
    <para>
     This is usually needed for homeserver discovery (from e.g. other Matrix clients).
     Further reference can be found in the <link xlink:href="https://spec.matrix.org/latest/client-server-api/#getwell-knownmatrixclient">upstream docs</link>
    </para>
   </callout>
   <callout arearefs='ex-matrix-synapse-rev-default'>
    <para>
     It's also possible to do a redirect here or something else, this vhost is not
     needed for Matrix. It's recommended though to <emphasis>not put</emphasis> element
     here, see also the <link linkend='ex-matrix-synapse-rev-default'>section about Element</link>.
    </para>
   </callout>
   <callout arearefs='ex-matrix-synapse-rev-proxy-pass'>
    <para>
     Forward all Matrix API calls to the synapse Matrix homeserver. A trailing slash
     <emphasis>must not</emphasis> be used here.
    </para>
   </callout>
   <callout arearefs='ex-matrix-synapse-rev-client'>
    <para>
     Forward requests for e.g. SSO and password-resets.
    </para>
   </callout>
  </calloutlist>
 </section>
 <section xml:id="module-services-matrix-register-users">
  <title>Registering Matrix users</title>
  <para>
   If you want to run a server with public registration by anybody, you can
   then enable <literal><link linkend="opt-services.matrix-synapse.settings.enable_registration">services.matrix-synapse.settings.enable_registration</link> =
   true;</literal>. Otherwise, or you can generate a registration secret with
   <command>pwgen -s 64 1</command> and set it with
   <option><link linkend="opt-services.matrix-synapse.settings.registration_shared_secret">services.matrix-synapse.settings.registration_shared_secret</link></option>.
   To create a new user or admin, run the following after you have set the secret
   and have rebuilt NixOS:
<screen>
<prompt>$ </prompt>nix-shell -p matrix-synapse
<prompt>$ </prompt>register_new_matrix_user -k <replaceable>your-registration-shared-secret</replaceable> http://localhost:8008
<prompt>New user localpart: </prompt><replaceable>your-username</replaceable>
<prompt>Password:</prompt>
<prompt>Confirm password:</prompt>
<prompt>Make admin [no]:</prompt>
Success!
</screen>
   In the example, this would create a user with the Matrix Identifier
   <literal>@your-username:example.org</literal>.
   <warning>
    <para>
     When using <xref linkend="opt-services.matrix-synapse.settings.registration_shared_secret" />, the secret
     will end up in the world-readable store. Instead it's recommended to deploy the secret
     in an additional file like this:
     <itemizedlist>
      <listitem>
       <para>
        Create a file with the following contents:
<programlisting>registration_shared_secret: your-very-secret-secret</programlisting>
       </para>
      </listitem>
      <listitem>
       <para>
        Deploy the file with a secret-manager such as <link xlink:href="https://nixops.readthedocs.io/en/latest/overview.html#managing-keys"><option>deployment.keys</option></link>
        from <citerefentry><refentrytitle>nixops</refentrytitle><manvolnum>1</manvolnum></citerefentry>
        or <link xlink:href="https://github.com/Mic92/sops-nix/">sops-nix</link> to
        e.g. <filename>/run/secrets/matrix-shared-secret</filename> and ensure that it's readable
        by <package>matrix-synapse</package>.
       </para>
      </listitem>
      <listitem>
       <para>
        Include the file like this in your configuration:
<programlisting>
{
  <xref linkend="opt-services.matrix-synapse.extraConfigFiles" /> = [
    "/run/secrets/matrix-shared-secret"
  ];
}
</programlisting>
       </para>
      </listitem>
     </itemizedlist>
    </para>
   </warning>
  </para>
  <note>
   <para>
    It's also possible to user alternative authentication mechanism such as
    <link xlink:href="https://github.com/matrix-org/matrix-synapse-ldap3">LDAP (via <literal>matrix-synapse-ldap3</literal>)</link>
    or <link xlink:href="https://matrix-org.github.io/synapse/latest/openid.html">OpenID</link>.
   </para>
  </note>
 </section>
 <section xml:id="module-services-matrix-element-web">
  <title>Element (formerly known as Riot) Web Client</title>

  <para>
   <link xlink:href="https://github.com/vector-im/riot-web/">Element Web</link> is
   the reference web client for Matrix and developed by the core team at
   matrix.org. Element was formerly known as Riot.im, see the
   <link xlink:href="https://element.io/blog/welcome-to-element/">Element introductory blog post</link>
   for more information. The following snippet can be optionally added to the code before
   to complete the synapse installation with a web client served at
   <code>https://element.myhostname.example.org</code> and
   <code>https://element.example.org</code>. Alternatively, you can use the hosted
   copy at <link xlink:href="https://app.element.io/">https://app.element.io/</link>,
   or use other web clients or native client applications. Due to the
   <literal>/.well-known</literal> urls set up done above, many clients should
   fill in the required connection details automatically when you enter your
   Matrix Identifier. See
   <link xlink:href="https://matrix.org/docs/projects/try-matrix-now.html">Try
   Matrix Now!</link> for a list of existing clients and their supported
   featureset.
<programlisting>
{
  services.nginx.virtualHosts."element.${fqdn}" = {
    <link linkend="opt-services.nginx.virtualHosts._name_.enableACME">enableACME</link> = true;
    <link linkend="opt-services.nginx.virtualHosts._name_.forceSSL">forceSSL</link> = true;
    <link linkend="opt-services.nginx.virtualHosts._name_.serverAliases">serverAliases</link> = [
      "element.${config.networking.domain}"
    ];

    <link linkend="opt-services.nginx.virtualHosts._name_.root">root</link> = pkgs.element-web.override {
      conf = {
        default_server_config = clientConfig; # see `clientConfig` from the snippet above.
      };
    };
  };
}
</programlisting>
  </para>

  <note>
   <para>
    The Element developers do not recommend running Element and your Matrix
    homeserver on the same fully-qualified domain name for security reasons. In
    the example, this means that you should not reuse the
    <literal>myhostname.example.org</literal> virtualHost to also serve Element,
    but instead serve it on a different subdomain, like
    <literal>element.example.org</literal> in the example. See the
    <link xlink:href="https://github.com/vector-im/element-web/tree/v1.10.0#important-security-notes">Element
    Important Security Notes</link> for more information on this subject.
   </para>
  </note>
 </section>
</chapter>