nixosTests.powerdns: test a complete setup

The test now check the following things:
- Configuring a MySQL server to hold the records
- Loading the PowerDNS schema from file
- Adding records through pdnsutil

nixos/tests/powerdns.nix

@@ -1,13 +1,65 @@
-import ./make-test-python.nix ({ pkgs, ... }: {
+# This test runs PowerDNS authoritative server with the
+# generic MySQL backend (gmysql) to connect to a
+# MariaDB server using UNIX sockets authentication.
+
+import ./make-test-python.nix ({ pkgs, lib, ... }: {
   name = "powerdns";
 
   nodes.server = { ... }: {
     services.powerdns.enable = true;
-    environment.systemPackages = [ pkgs.dnsutils ];
+    services.powerdns.extraConfig = ''
+      launch=gmysql
+      gmysql-user=pdns
+    '';
+
+    services.mysql = {
+      enable = true;
+      package = pkgs.mariadb;
+      ensureDatabases = [ "powerdns" ];
+      ensureUsers = lib.singleton
+        { name = "pdns";
+          ensurePermissions = { "powerdns.*" = "ALL PRIVILEGES"; };
+        };
+    };
+
+    environment.systemPackages = with pkgs;
+      [ dnsutils powerdns mariadb ];
   };
 
   testScript = ''
-    server.wait_for_unit("pdns")
+    import re
-    server.succeed("dig version.bind txt chaos \@127.0.0.1")
+
+    with subtest("PowerDNS database exists"):
+        server.wait_for_unit("mysql")
+        server.succeed("echo 'SHOW DATABASES;' | sudo -u pdns mysql -u pdns >&2")
+
+    with subtest("Loading the MySQL schema works"):
+        server.succeed(
+            "sudo -u pdns mysql -u pdns -D powerdns <"
+            "${pkgs.powerdns}/share/doc/pdns/schema.mysql.sql"
+        )
+
+    with subtest("PowerDNS server starts"):
+        server.wait_for_unit("pdns")
+        server.succeed("dig version.bind txt chaos @127.0.0.1 >&2")
+
+    with subtest("Adding an example zone works"):
+        # Extract configuration file needed by pdnsutil
+        unit = server.succeed("systemctl cat pdns")
+        conf = re.search("(--config-dir=[^ ]+)", unit).group(1)
+        pdnsutil = "sudo -u pdns pdnsutil " + conf
+        server.succeed(f"{pdnsutil} create-zone example.com ns1.example.com")
+        server.succeed(f"{pdnsutil} add-record  example.com ns1 A 192.168.1.2")
+
+    with subtest("Querying the example zone works"):
+        reply = server.succeed("dig +noall +answer ns1.example.com @127.0.0.1")
+        assert (
+            "192.168.1.2" in reply
+        ), f""""
+        The reply does not contain the expected IP address:
+          Expected:
+            ns1.example.com.        3600    IN      A       192.168.1.2
+          Reply:
+            {reply}"""
   '';
 })