add sh to image

flake.nix

@@ -32,9 +32,10 @@
         };
         dockerImage = pkgs.dockerTools.buildLayeredImage {
           name = "policy_service";
-          contents = [ package ];
+          contents = [ package pkgs.bashInteractive pkgs.shadow ];
           config = {
             Cmd = [ "${package}/bin/policy_service" "start" ];
+            Entrypoint = [ "/bin/sh" ];
           };
         };
       in