nixpkgs/nixos/tests/containers-reloadable.nix

import ./make-test.nix ({ pkgs, lib, ...} :
let
  client_base = {
    
    containers.test1 = {
      autoStart = true;
      config = {
        environment.etc.check.text = "client_base";
      };
    };

    # prevent make-test.nix to change IP
    networking.interfaces = {
      eth1.ipv4.addresses = lib.mkOverride 0 [ ];
    };
  };
in {
  name = "cotnainers-reloadable";
  meta = with pkgs.stdenv.lib.maintainers; {
    maintainers = [ danbst ];
  };

  nodes = {
    client = { ... }: {
      imports = [ client_base ];
    };

    client_c1 = { lib, ... }: {
      imports = [ client_base ];

      containers.test1.config = {
        environment.etc.check.text = lib.mkForce "client_c1";
        services.httpd.enable = true;
        services.httpd.adminAddr = "nixos@example.com";
      };
    };
    client_c2 = { lib, ... }: {
      imports = [ client_base ];

      containers.test1.config = {
        environment.etc.check.text = lib.mkForce "client_c2";
        services.nginx.enable = true;
      };
    };
  };

  testScript = {nodes, ...}: let
    c1System = nodes.client_c1.config.system.build.toplevel;
    c2System = nodes.client_c2.config.system.build.toplevel;
  in ''
    $client->start();
    $client->waitForUnit("default.target");
    $client->succeed("[[ \$(nixos-container run test1 cat /etc/check) == client_base ]] >&2");

    $client->succeed("${c1System}/bin/switch-to-configuration test >&2");
    $client->succeed("[[ \$(nixos-container run test1 cat /etc/check) == client_c1 ]] >&2");
    $client->succeed("systemctl status httpd -M test1 >&2");

    $client->succeed("${c2System}/bin/switch-to-configuration test >&2");
    $client->succeed("[[ \$(nixos-container run test1 cat /etc/check) == client_c2 ]] >&2");
    $client->fail("systemctl status httpd -M test1 >&2");
    $client->succeed("systemctl status nginx -M test1 >&2");
  '';

})