postgres support

shell.nix

@@ -1,5 +1,6 @@
 let
   nixpkgs = fetchTarball "https://github.com/NixOS/nixpkgs/tarball/nixos-25.05";
+  postgresDirectory = ".data/postgres";
 
   pkgs = import nixpkgs {
     config = { };
@@ -21,15 +22,28 @@ let
       );
     in
     [
-      phpForRuntimeWithXDebug
-      pkgs.treefmt
+      pkgs.postgresql_16
       pkgs.nixfmt-rfc-style
       pkgs.gnumake
+      phpForRuntimeWithXDebug
       pkgs.php82Extensions.curl
       pkgs.php82Packages.composer
     ];
 in
 pkgs.mkShell {
   inherit packages;
-}
 
+  shellHook = ''
+    # https://yannesposito.com/posts/0024-replace-docker-compose-with-nix-shell/index.html
+    if [ ! -d var/log ]; then
+       mkdir -p var/log
+    fi
+    if [ ! -d ${postgresDirectory} ]; then
+      mkdir -p ${postgresDirectory}
+      initdb -D ${postgresDirectory}
+      pg_ctl -D ${postgresDirectory} -l var/log/postgres.log -o "--unix_socket_directories='$PWD'" start
+      createdb app
+      pg_ctl -D ${postgresDirectory} stop
+    fi
+  '';
+}