nixpkgs/nixos/doc/manual/release-notes/rl-1909.xml

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         xmlns:xlink="http://www.w3.org/1999/xlink"
         xmlns:xi="http://www.w3.org/2001/XInclude"
         version="5.0"
         xml:id="sec-release-19.09">
 <title>Release 19.09 (“Loris”, 2019/09/??)</title>

 <section 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="sec-release-19.09-highlights">
  <title>Highlights</title>

  <para>
   In addition to numerous new and upgraded packages, this release has the
   following highlights:
  </para>

  <itemizedlist>
   <listitem>
    <para />
   </listitem>
  </itemizedlist>
 </section>

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         xmlns:xlink="http://www.w3.org/1999/xlink"
         xmlns:xi="http://www.w3.org/2001/XInclude"
         version="5.0"
         xml:id="sec-release-19.09-new-services">
  <title>New Services</title>

  <para>
   The following new services were added since the last release:
  </para>

  <itemizedlist>
   <listitem>
    <para>
       Besides the existing <option>services.prometheus</option> module which
       targets Prometheus-1 a new <option>services.prometheus2</option> module
       has been added which targets Prometheus-2.
    </para>
    <para>
       Both modules can be enabled at the same time. In fact
       <link xlink:href="https://prometheus.io/docs/prometheus/latest/migration/#storage">
       this is needed for upgrading existing Prometheus-1 data to Prometheus-2
       </link>.
    </para>
   </listitem>
  </itemizedlist>
 </section>

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         xmlns:xlink="http://www.w3.org/1999/xlink"
         xmlns:xi="http://www.w3.org/2001/XInclude"
         version="5.0"
         xml:id="sec-release-19.09-incompatibilities">
  <title>Backward Incompatibilities</title>

  <para>
   When upgrading from a previous release, please be aware of the following
   incompatible changes:
  </para>

  <itemizedlist>
   <listitem>
    <para>
     Buildbot no longer supports Python 2, as support was dropped upstream in
     version 2.0.0. Configurations may need to be modified to make them
     compatible with Python 3.
    </para>
   </listitem>
   <listitem>
    <para>
     PostgreSQL now uses
     <filename class="directory">/run/postgresql</filename> as its socket
     directory instead of <filename class="directory">/tmp</filename>. So
     if you run an application like eg. Nextcloud, where you need to use
     the Unix socket path as the database host name, you need to change it
     accordingly.
    </para>
   </listitem>
   <listitem>
    <para>
      The directory where Prometheus will store its metric data is now
      managed by systemd's StateDirectory mechanism. It still defaults
      to <literal>/var/lib/prometheus</literal>.
    </para>
    <para>
      Its location can be specified by the new
      <option>services.prometheus.stateDir</option> option which
      defaults to <literal>prometheus</literal>. Note that this should
      be a directory relative to <literal>/var/lib/</literal>.
    </para>
    <para>
      The option <option>services.prometheus.dataDir</option> has been
      deprecated. You can still set it but it's now required to have
      <literal>/var/lib/</literal> as a prefix and you can't set
      <option>services.prometheus.stateDir</option> at the same time.
    </para>
   </listitem>
  </itemizedlist>
 </section>

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         xmlns:xlink="http://www.w3.org/1999/xlink"
         xmlns:xi="http://www.w3.org/2001/XInclude"
         version="5.0"
         xml:id="sec-release-19.09-notable-changes">
  <title>Other Notable Changes</title>

  <itemizedlist>
   <listitem>
    <para>
     The <option>documentation</option> module gained an option named
     <option>documentation.nixos.includeAllModules</option> which makes the
     generated <citerefentry>
     <refentrytitle>configuration.nix</refentrytitle>
     <manvolnum>5</manvolnum></citerefentry> manual page include all options
     from all NixOS modules included in a given
     <literal>configuration.nix</literal> configuration file. Currently, it is
     set to <literal>false</literal> by default as enabling it frequently
     prevents evaluation. But the plan is to eventually have it set to
     <literal>true</literal> by default. Please set it to
     <literal>true</literal> now in your <literal>configuration.nix</literal>
     and fix all the bugs it uncovers.
    </para>
   </listitem>
   <listitem>
    <para>
     The <literal>vlc</literal> package gained support for Chromecast
     streaming, enabled by default. TCP port 8010 must be open for it to work,
     so something like <literal>networking.firewall.allowedTCPPorts = [ 8010
     ];</literal> may be required in your configuration. Also consider enabling
     <link xlink:href="https://nixos.wiki/wiki/Accelerated_Video_Playback">
     Accelerated Video Playback</link> for better transcoding performance.
    </para>
   </listitem>
  </itemizedlist>
 </section>
</section>