fake-nss: Add support for extra passwd and group lines

# Useful when packaging binaries that insist on using nss to look up

# username/groups (like nginx).

# /bin/sh is fine to not exist, and provided by another shim.

{ symlinkJoin, writeTextDir, runCommand }:

{ lib, symlinkJoin, writeTextDir, runCommand, extraPasswdLines ? [], extraGroupLines ? [] }:

symlinkJoin {

  name = "fake-nss";

  paths = [

    (writeTextDir "etc/passwd" ''

      root:x:0:0:root user:/var/empty:/bin/sh

      nobody:x:65534:65534:nobody:/var/empty:/bin/sh

      ${lib.concatStrings (map (line: line + "\n") extraPasswdLines)}nobody:x:65534:65534:nobody:/var/empty:/bin/sh

    '')

    (writeTextDir "etc/group" ''

      root:x:0:

      nobody:x:65534:

      ${lib.concatStrings (map (line: line + "\n") extraGroupLines)}nobody:x:65534:

    '')

    (writeTextDir "etc/nsswitch.conf" ''

      hosts: files dns