nixos/tests; add haproxy

(cherry picked from commit e1790030262d1ce4a28144363469af96a588b21d)

nixos/release.nix

@@ -290,6 +290,7 @@ in rec {
   tests.grafana = callTest tests/grafana.nix {};
   tests.graphite = callTest tests/graphite.nix {};
   tests.hardened = callTest tests/hardened.nix { };
+  tests.haproxy = callTest tests/haproxy.nix {};
   tests.hibernate = callTest tests/hibernate.nix {};
   tests.home-assistant = callTest tests/home-assistant.nix { };
   tests.hound = callTest tests/hound.nix {};

nixos/tests/haproxy.nix

@@ -0,0 +1,41 @@
+import ./make-test.nix ({ pkgs, ...}: {
+  name = "haproxy";
+  nodes = {
+    machine = { config, ...}: {
+      imports = [ ../modules/profiles/minimal.nix ];
+      services.haproxy = {
+        enable = true;
+        config = ''
+          defaults
+            timeout connect 10s
+
+          backend http_server
+            mode http
+            server httpd [::1]:8000
+
+          frontend http
+            bind *:80
+            mode http
+            use_backend http_server
+        '';
+      };
+      services.httpd = {
+        enable = true;
+        documentRoot = pkgs.writeTextDir "index.txt" "We are all good!";
+        adminAddr = "notme@yourhost.local";
+        listen = [{
+          ip = "::1";
+          port = 8000;
+        }];
+      };
+    };
+  };
+  testScript = ''
+    startAll;
+    $machine->waitForUnit('multi-user.target');
+    $machine->waitForUnit('haproxy.service');
+    $machine->waitForUnit('httpd.service');
+    $machine->succeed('curl -k http://localhost:80/index.txt | grep "We are all good!"');
+
+  '';
+})