Restless CGI configuration for Nix

This is a Nix function that makes a systemd service definition for a CGI web server that serves a simple directory of CGI scripts, which you can define inline in your Nix configuration.

Here's an example from a configuration.nix:

systemd.services.cgi-example =
  (import (pkgs.fetchFromGitHub {
    owner = "lessrest";
    repo = "restless-cgi";
    rev = "bf95bccc2ce65bcda1b91a149a2764d97b185319";
    sha256 = "0kfkcdskij3ngv43ajlhwm31yqy3a3mbnx9kbdjaqhp0179cjx8j";
  }) { inherit pkgs; }) {
    port = 1988;
    user = "someone";
    scripts = {
      foo = ''
        #!${pkgs.bash}/bin/bash
        printf "Content-Type: text/plain\n"
        printf "\r\n"
        echo wow, foo
      '';
      bar = ''
        #!${pkgs.bash}/bin/bash
        printf "Content-Type: text/plain\n"
        printf "\r\n"
        echo wow, bar
      '';
    };
  };

This refers to the previous commit, since I'm not Quine enough to get the hash of the current commit into the source code of the current commit.

(The user chosen must be able to write to /tmp, so don't use nobody.)

The configuration uses Kazu Yamamoto's nice Mighttpd2 CGI server, written in Haskell and based on the Warp HTTP server (which is fast and robust).