add ability to create default user

lib.nix

@@ -115,6 +115,26 @@ in
             echo "Checking presence of database ${db.name}"
             dbAlreadyExists="$(echo "SELECT 1 AS result FROM pg_database WHERE datname='${db.name}';" | psql --dbname postgres | ${pkgs.gnugrep}/bin/grep -c 'exists = "1"' || true)"
             echo "$dbAlreadyExists"
+            if [ 1 -ne "$dbAlreadyExists" ]; then
+              echo "Creating database ${db.name}"
+              echo 'CREATE DATABASE "${db.name}";' | psql --dbname postgres
+              ${lib.optionalString (db.user != null && db.password != null) ''
+                echo "Creating user ${db.user}"
+                psql --dbname postgres <<'EOF'
+                DO $$
+                  BEGIN
+                    CREATE ROLE "${db.user}" WITH LOGIN PASSWORD '${db.password}';
+                    EXCEPTION WHEN duplicate_object THEN RAISE NOTICE '%, skipping', SQLERRM USING ERRCODE = SQLSTATE;
+                  END
+                $$;
+                GRANT ALL PRIVILEGES ON DATABASE "${db.name}" TO "${db.user}";
+                \c ${db.name}
+                GRANT ALL PRIVILEGES ON SCHEMA public TO "${db.user}";
+                EOF
+              ''}
+            else
+              echo "Database ${db.name} already exists"
+            fi
           '') initialDatabases)
         else
           "";