lemmy: break pict-rs config into own unit & persist its data

hosts/by-name/servo/services/default.nix

@@ -19,6 +19,7 @@
     ./navidrome.nix
     ./nixserve.nix
     ./nginx.nix
+    ./pict-rs.nix
     ./pleroma.nix
     ./postgres.nix
     ./prosody.nix

hosts/by-name/servo/services/pict-rs.nix

@@ -0,0 +1,23 @@
+# pict-rs is an image database/store used by Lemmy.
+# i don't explicitly activate it here -- just adjust its defaults to be a bit friendlier
+{ config, lib, ... }:
+let
+  cfg = config.services.pict-rs;
+in
+{
+  sane.persist.sys.plaintext = lib.mkIf cfg.enable [
+    { user = "pict-rs"; group = "pict-rs"; directory = cfg.dataDir; }
+  ];
+
+  systemd.services.pict-rs.serviceConfig = {
+    # fix to use a normal user so we can configure perms correctly
+    DynamicUser = lib.mkForce false;
+    User = "pict-rs";
+    Group = "pict-rs";
+  };
+  users.groups.pict-rs = {};
+  users.users.pict-rs = {
+    group = "pict-rs";
+    isSystemUser = true;
+  };
+}

hosts/common/ids.nix

@@ -38,6 +38,8 @@
   sane.ids.komga.gid = 2407;
   sane.ids.lemmy.uid = 2408;
   sane.ids.lemmy.gid = 2408;
+  sane.ids.pict-rs.uid = 2409;
+  sane.ids.pict-rs.gid = 2409;
 
   sane.ids.colin.uid = 1000;
   sane.ids.guest.uid = 1100;