preliminary changes for password file in postgres

postgresdb/default.nix

@@ -1,8 +1,17 @@
-{ stdenv, pkgs }:
-{ postgresUsername
-, postgresPassword
-, postgresDatabase
+{ stdenv
+, pkgs
+, lib
 }:
+{ postgresDatabase
+, postgresUsername
+, postgresPassword ? null
+, postgresPasswordFile ? null
+}:
+
+assert lib.assertMsg (
+  (postgresPassword == null && postgresPasswordFile != null)
+  || (postgresPassword != null && postgresPasswordFile == null)
+) "set either postgresPassword or postgresPasswordFile";
 
 # From https://github.com/svanderburg/dysnomia/blob/master/dysnomia-modules/postgresql-database.in
 # and https://github.com/svanderburg/dysnomia/blob/master/tests/deployment/postgresql-database.nix

postgresdb/mkdefault.nix

@@ -1,18 +1,22 @@
 { PostgresDB
 }:
 { name
-, username
-, password
 , database
+, username
+, password ? null
+, passwordFile ? null
 , dependsOn ? {}
 }:
 
 {
   inherit name;
+  inherit database username password passwordFile;
+
   pkg = PostgresDB {
+    postgresDatabase = database;
     postgresUsername = username;
     postgresPassword = password;
-    postgresDatabase = database;
+    postgresPasswordFile = passwordFile;
   };
 
   inherit dependsOn;