{ pkgs ? import <nixpkgs> {}, name, packages ? {}}:

with pkgs;
let
  # We need bash and coreutils to display the container "run" message;
  # dockerTools.buildImage expects a list of derivations, not a set
  required = { inherit bash coreutils; };
  contents = builtins.attrValues (required // packages);

  prettyPrint = import ./prettyPrint.nix {};

in dockerTools.buildImage {
  inherit name contents;

  config = {
    Cmd = [ "${bash}/bin/bash" "-c" ''
      ( ${coreutils}/bin/cat | ${coreutils}/bin/fmt -s ) >&2 <<EOF
      This is the "${name}" container, containing the following software:

      ${prettyPrint packages}

      Execute these tools explicitly from within the container, rather than running the container itself.
      EOF
    '' ];
  };
}