diff --git a/Ttrss/default.nix b/Ttrss/default.nix
index 6c5f66a..44999f6 100644
--- a/Ttrss/default.nix
+++ b/Ttrss/default.nix
@@ -2,13 +2,18 @@
 , pkgs
 , lib
 }:
-{ documentRoot
+{ document_root
 , name ? "ttrss"
 , user ? "http"
 , group ? "http"
-, lock_directory ? "/run/${name}/lock"
-, cache_dir ? "/run/${name}/cache"
-, icons_dir ? "${documentRoot}/feed-icons"
+, lock_directory
+, cache_directory
+, feed_icons_directory
+, db_host
+, db_port
+, db_username
+, db_database
+, db_password
 }:
 { TtrssPostgresDB
 }:
@@ -23,11 +28,11 @@ let
 
   config = self_url_path: {
     db_type = "pgsql";
-    db_host = TtrssPostgresDB.target.properties.hostname;
-    db_user = TtrssPostgresDB.postgresUsername;
-    db_name = TtrssPostgresDB.postgresDatabase;
-    db_pass = TtrssPostgresDB.postgresPassword;
-    db_port = builtins.toString TtrssPostgresDB.postgresPort;
+    db_host = db_host {inherit TtrssPostgresDB;};
+    db_port = builtins.toString db_port;
+    db_user = db_username;
+    db_name = db_database;
+    db_pass = db_password;
 
     self_url_path = self_url_path;
     single_user_mode = "true";
@@ -35,8 +40,8 @@ let
     php_executable = "${pkgs.php}/bin/php";
 
     lock_directory = "${lock_directory}";
-    cache_dir = "${cache_dir}";
-    icons_dir = "${icons_dir}";
+    cache_dir = "${cache_directory}";
+    icons_dir = "${feed_icons_directory}";
     icons_url = "feed-icons";
 
     auth_auto_create = "true";
@@ -68,18 +73,19 @@ stdenv.mkDerivation rec {
   buildCommand =
     let
       configFile = pkgs.writeText "config.php" (asTtrssConfig (config "https://${name}.tiserbox.com/"));
+      dr = dirOf document_root;
     in
       ''
       mkdir -p $out/${name}
       cp -ra $src/* $out/${name}
       cp ${configFile} $out/${name}/config.php
 
-      echo "${documentRoot}" > $out/.dysnomia-targetdir
+      echo "${dr}" > $out/.dysnomia-targetdir
       echo "${user}:${group}" > $out/.dysnomia-filesetowner
       
       cat > $out/.dysnomia-fileset <<FILESET
         symlink $out/${name}
-        target ${documentRoot}
+        target ${dr}
       FILESET
       '';
 }
diff --git a/Ttrss/environment.nix b/Ttrss/environment.nix
new file mode 100644
index 0000000..c4c1bde
--- /dev/null
+++ b/Ttrss/environment.nix
@@ -0,0 +1,37 @@
+{}:
+{
+  name ? "ttrss",
+  document_root ? "/usr/share/webapps/${name}",
+  systemd_run ? "/run/${name}",
+  persistent_dir ? "/var/lib/${name}"
+}:
+rec {
+  inherit name document_root systemd_run persistent_dir;
+
+  lock_directory = "${systemd_run}/lock";
+  cache_directory = "${systemd_run}/cache";
+  feed_icons_directory = "${persistent_dir}/feed-icons";
+
+  ro_directories = [];
+  rw_directories = [
+    lock_directory
+    cache_directory
+    feed_icons_directory
+  ];
+
+  directories_modes = {
+    "${systemd_run}" = "0555";
+    "${lock_directory}" = "0755";
+    "${cache_directory}" = "0755";
+    "${cache_directory}/upload" = "0755";
+    "${cache_directory}/images" = "0755";
+    "${cache_directory}/export" = "0755";
+    "${persistent_dir}/feed-icons" = "0755";
+  };
+
+  postgresql = {
+    username = name;
+    password = "ttrsspw";
+    database = name;
+  };
+}
diff --git a/Ttrss/update.nix b/Ttrss/update.nix
index 0c82cf0..051f5a3 100644
--- a/Ttrss/update.nix
+++ b/Ttrss/update.nix
@@ -3,8 +3,10 @@
 , lib
 , utils
 }:
-{ readOnlyPaths ? []
+{ document_root
+, readOnlyPaths ? []
 , readWritePaths ? []
+, postgresServiceName
 }:
 { TtrssService
 , TtrssPostgresDB
@@ -20,15 +22,15 @@
 # - LOCK_DIRECTORY should be writable.
 
 let
-  fullPath = "${TtrssService.documentRoot}/${TtrssService.documentName}";
+  fullPath = "${document_root}";
   roPaths = [fullPath] ++ readOnlyPaths;
 in
-utils.systemd-service-derivation rec {
+utils.systemd.mkService rec {
   name = "ttrss-update";
   content = ''
     [Unit]
     Description=${name}
-    After=network.target ${TtrssPostgresDB.postgresServiceName}
+    After=network.target ${postgresServiceName}
     
     [Service]
     User=${TtrssService.user}
diff --git a/all-packages.nix b/all-packages.nix
index 5fc20c6..a9cdf8b 100644
--- a/all-packages.nix
+++ b/all-packages.nix
@@ -11,6 +11,7 @@ let
   self = {
     PostgresDB = callPackage ./PostgresDB {};
 
+    TtrssEnvironment = callPackage ./Ttrss/environment.nix {};
     TtrssService = callPackage ./Ttrss {};
     TtrssUpdateService = callPackage ./Ttrss/update.nix {inherit utils;};
     TtrssUpgradeDBService = callPackage ./Ttrss/dbupgrade.nix {};