nixos/unifi: refactor mountpoints

Use service internal bind mounts instead of global ones.

This also moves the logs to /var/log/unifi on the host
and the run directory to /run/unifi.

Closes #61424

nixos/doc/manual/from_md/release-notes/rl-2111.section.xml

···
           </listitem>
         </itemizedlist>
       </listitem>
+      <listitem>
+        <para>
+          The
+          <link xlink:href="options.html#opt-services.unifi.enable">services.unifi</link>
+          module has been reworked, solving a number of issues. This
+          leads to several user facing changes:
+        </para>
+        <itemizedlist spacing="compact">
+          <listitem>
+            <para>
+              The <literal>services.unifi.dataDir</literal> option is
+              removed and the data is now always located under
+              <literal>/var/lib/unifi/data</literal>. This is done to
+              make better use of systemd state direcotiry and thus
+              making the service restart more reliable.
+            </para>
+          </listitem>
+          <listitem>
+            <para>
+              The unifi logs can now be found under:
+              <literal>/var/log/unifi</literal> instead of
+              <literal>/var/lib/unifi/logs</literal>.
+            </para>
+          </listitem>
+          <listitem>
+            <para>
+              The unifi run directory can now be found under:
+              <literal>/run/unifi</literal> instead of
+              <literal>/var/lib/unifi/run</literal>.
+            </para>
+          </listitem>
+        </itemizedlist>
+      </listitem>
     </itemizedlist>
   </section>
 </section>

nixos/doc/manual/release-notes/rl-2111.section.md

···
 - Dokuwiki now supports caddy! However
   - the nginx option has been removed, in the new configuration, please use the `dokuwiki.webserver = "nginx"` instead.
   - The "${hostname}" option has been deprecated, please use `dokuwiki.sites = [ "${hostname}" ]` instead
+
+- The [services.unifi](options.html#opt-services.unifi.enable) module has been reworked, solving a number of issues. This leads to several user facing changes:
+  - The `services.unifi.dataDir` option is removed and the data is now always located under `/var/lib/unifi/data`. This is done to make better use of systemd state direcotiry and thus making the service restart more reliable.
+  - The unifi logs can now be found under: `/var/log/unifi` instead of `/var/lib/unifi/logs`.
+  - The unifi run directory can now be found under: `/run/unifi` instead of `/var/lib/unifi/run`.

nixos/modules/services/networking/unifi.nix

···
         ${optionalString (cfg.maximumJavaHeapSize != null) "-Xmx${(toString cfg.maximumJavaHeapSize)}m"} \
         -jar ${stateDir}/lib/ace.jar
   '';
-  mountPoints = [
-    {
-      what = "${cfg.unifiPackage}/dl";
-      where = "${stateDir}/dl";
-    }
-    {
-      what = "${cfg.unifiPackage}/lib";
-      where = "${stateDir}/lib";
-    }
-    {
-      what = "${cfg.mongodbPackage}/bin";
-      where = "${stateDir}/bin";
-    }
-    {
-      what = "${cfg.dataDir}";
-      where = "${stateDir}/data";
-    }
-  ];
-  systemdMountPoints = map (m: "${utils.escapeSystemdPath m.where}.mount") mountPoints;
 in
 {
 
···
       '';
     };
 
-    services.unifi.dataDir = mkOption {
-      type = types.str;
-      default = "${stateDir}/data";
-      description = ''
-        Where to store the database and other data.
-
-        This directory will be bind-mounted to ${stateDir}/data as part of the service startup.
-      '';
-    };
-
     services.unifi.openPorts = mkOption {
       type = types.bool;
       default = true;
···
       ];
     };
 
-    # We must create the binary directories as bind mounts instead of symlinks
-    # This is because the controller resolves all symlinks to absolute paths
-    # to be used as the working directory.
-    systemd.mounts = map ({ what, where }: {
-        bindsTo = [ "unifi.service" ];
-        partOf = [ "unifi.service" ];
-        unitConfig.RequiresMountsFor = stateDir;
-        options = "bind";
-        what = what;
-        where = where;
-      }) mountPoints;
-
-    systemd.tmpfiles.rules = [
-      "d '${stateDir}' 0700 unifi - - -"
-      "d '${stateDir}/data' 0700 unifi - - -"
-      "d '${stateDir}/webapps' 0700 unifi - - -"
-      "L+ '${stateDir}/webapps/ROOT' - - - - ${cfg.unifiPackage}/webapps/ROOT"
-    ];
-
     systemd.services.unifi = {
       description = "UniFi controller daemon";
       wantedBy = [ "multi-user.target" ];
-      after = [ "network.target" ] ++ systemdMountPoints;
-      partOf = systemdMountPoints;
-      bindsTo = systemdMountPoints;
-      unitConfig.RequiresMountsFor = stateDir;
+      after = [ "network.target" ];
+
       # This a HACK to fix missing dependencies of dynamic libs extracted from jars
       environment.LD_LIBRARY_PATH = with pkgs.stdenv; "${cc.cc.lib}/lib";
       # Make sure package upgrades trigger a service restart
···
         SystemCallErrorNumber = "EPERM";
         SystemCallFilter = [ "@system-service" ];
 
-        # Required for ProtectSystem=strict
-        BindPaths = [ stateDir ];
+        StateDirectory = "unifi";
+        RuntimeDirectory = "unifi";
+        LogsDirectory = "unifi";
+        CacheDirectory= "unifi";
+
+        TemporaryFileSystem = [
+          # required as we want to create bind mounts below
+          "${stateDir}/webapps:rw"
+        ];
+
+        # We must create the binary directories as bind mounts instead of symlinks
+        # This is because the controller resolves all symlinks to absolute paths
+        # to be used as the working directory.
+        BindPaths =  [
+          "/var/log/unifi:${stateDir}/logs"
+          "/run/unifi:${stateDir}/run"
+          "${cfg.unifiPackage}/dl:${stateDir}/dl"
+          "${cfg.unifiPackage}/lib:${stateDir}/lib"
+          "${cfg.mongodbPackage}/bin:${stateDir}/bin"
+          "${cfg.unifiPackage}/webapps/ROOT:${stateDir}/webapps/ROOT"
+        ];
 
         # Needs network access
         PrivateNetwork = false;
···
     };
 
   };
+  imports = [
+    (mkRemovedOptionModule [ "services" "unifi" "dataDir" ] "You should move contents of dataDir to /var/lib/unifi/data" )
+  ];
 
   meta.maintainers = with lib.maintainers; [ erictapen pennae ];
 }