nixpkgs/nixos/tests/nscd.nix

import ./make-test-python.nix ({ pkgs, ... }:
let
  # build a getent that itself doesn't see anything in /etc/hosts and
  # /etc/nsswitch.conf, by using libredirect to steer its own requests to
  # /dev/null.
  # This means is /has/ to go via nscd to actuallly resolve any of the
  # additionally configured hosts.
  getent' = pkgs.writeScript "getent-without-etc-hosts" ''
    export NIX_REDIRECTS=/etc/hosts=/dev/null:/etc/nsswitch.conf=/dev/null
    export LD_PRELOAD=${pkgs.libredirect}/lib/libredirect.so
    exec getent $@
  '';
in
{
  name = "nscd";

  nodes.machine = { pkgs, ... }: {
    imports = [ common/user-account.nix ];
    networking.extraHosts = ''
      2001:db8::1 somehost.test
      192.0.2.1 somehost.test
    '';

    systemd.services.sockdump = {
      wantedBy = [ "multi-user.target" ];
      path = [
        # necessary for bcc to unpack kernel headers and invoke modprobe
        pkgs.gnutar
        pkgs.xz.bin
        pkgs.kmod
      ];
      environment.PYTHONUNBUFFERED = "1";

      serviceConfig = {
        ExecStart = "${pkgs.sockdump}/bin/sockdump /var/run/nscd/socket";
        Restart = "on-failure";
        RestartSec = "1";
        Type = "simple";
      };
    };

    specialisation = {
      withGlibcNscd.configuration = { ... }: {
        services.nscd.enableNsncd = false;
      };
      withUnscd.configuration = { ... }: {
        services.nscd.enableNsncd = false;
        services.nscd.package = pkgs.unscd;
      };
    };
  };

  testScript = { nodes, ... }:
    let
      specialisations = "${nodes.machine.system.build.toplevel}/specialisation";
    in
    ''
      # Regression test for https://github.com/NixOS/nixpkgs/issues/50273
      def test_dynamic_user():
          with subtest("DynamicUser actually allocates a user"):
              assert "iamatest" in machine.succeed(
                  "systemd-run --pty --property=Type=oneshot --property=DynamicUser=yes --property=User=iamatest whoami"
              )

      # Test resolution of somehost.test with getent', to make sure we go via
      # nscd protocol
      def test_host_lookups():
          with subtest("host lookups via nscd protocol"):
              # ahosts
              output = machine.succeed("${getent'} ahosts somehost.test")
              assert "192.0.2.1" in output
              assert "2001:db8::1" in output

              # ahostsv4
              output = machine.succeed("${getent'} ahostsv4 somehost.test")
              assert "192.0.2.1" in output
              assert "2001:db8::1" not in output

              # ahostsv6
              output = machine.succeed("${getent'} ahostsv6 somehost.test")
              assert "192.0.2.1" not in output
              assert "2001:db8::1" in output

              # reverse lookups (hosts)
              assert "somehost.test" in machine.succeed("${getent'} hosts 2001:db8::1")
              assert "somehost.test" in machine.succeed("${getent'} hosts 192.0.2.1")


      # Test host resolution via nss modules works
      # We rely on nss-myhostname in this case, which resolves *.localhost and
      # _gateway.
      # We don't need to use getent' here, as non-glibc nss modules can only be
      # discovered via nscd.
      def test_nss_myhostname():
          with subtest("nss-myhostname provides hostnames (ahosts)"):
              # ahosts
              output = machine.succeed("getent ahosts foobar.localhost")
              assert "::1" in output
              assert "127.0.0.1" in output

              # ahostsv4
              output = machine.succeed("getent ahostsv4 foobar.localhost")
              assert "::1" not in output
              assert "127.0.0.1" in output

              # ahostsv6
              output = machine.succeed("getent ahostsv6 foobar.localhost")
              assert "::1" in output
              assert "127.0.0.1" not in output

      start_all()
      machine.wait_for_unit("default.target")

      # give sockdump some time to finish attaching.
      machine.sleep(5)

      # Test all tests with glibc-nscd.
      test_dynamic_user()
      test_host_lookups()
      test_nss_myhostname()

      with subtest("glibc-nscd"):
          machine.succeed('${specialisations}/withGlibcNscd/bin/switch-to-configuration test')
          machine.wait_for_unit("default.target")

          test_dynamic_user()
          test_host_lookups()
          test_nss_myhostname()

      with subtest("unscd"):
          machine.succeed('${specialisations}/withUnscd/bin/switch-to-configuration test')
          machine.wait_for_unit("default.target")

          # known to fail, unscd doesn't load external NSS modules
          # test_dynamic_user()

          test_host_lookups()

          # known to fail, unscd doesn't load external NSS modules
          # test_nss_myhostname()
    '';
})