nixos/tests/pppd: init

This test creates a PPPoE link between two machines, and verifies
that the machines can ping each other.

nixos/tests/all-tests.nix

@@ -227,6 +227,7 @@ in
   postgresql = handleTest ./postgresql.nix {};
   postgresql-wal-receiver = handleTest ./postgresql-wal-receiver.nix {};
   powerdns = handleTest ./powerdns.nix {};
+  pppd = handleTest ./pppd.nix {};
   predictable-interface-names = handleTest ./predictable-interface-names.nix {};
   printing = handleTest ./printing.nix {};
   prometheus = handleTest ./prometheus.nix {};

nixos/tests/pppd.nix

@@ -0,0 +1,62 @@
+import ./make-test.nix (
+  let
+    chap-secrets = {
+      text = ''"flynn" * "reindeerflotilla" *'';
+      mode = "0640";
+    };
+  in {
+    nodes = {
+      server = {config, pkgs, ...}: {
+        config = {
+          # Run a PPPoE access concentrator server. It will spawn an
+          # appropriate PPP server process when a PPPoE client sets up a
+          # PPPoE session.
+          systemd.services.pppoe-server = {
+            restartTriggers = [
+              config.environment.etc."ppp/pppoe-server-options".source
+              config.environment.etc."ppp/chap-secrets".source
+            ];
+            after = ["network.target"];
+            serviceConfig = {
+              ExecStart = "${pkgs.rpPPPoE}/sbin/pppoe-server -F -O /etc/ppp/pppoe-server-options -q ${pkgs.ppp}/sbin/pppd -I eth1 -L 192.0.2.1 -R 192.0.2.2";
+            };
+            wantedBy = ["multi-user.target"];
+          };
+          environment.etc = {
+            "ppp/pppoe-server-options".text = ''
+              lcp-echo-interval 10
+              lcp-echo-failure 2
+              plugin rp-pppoe.so
+              require-chap
+              nobsdcomp
+              noccp
+              novj
+            '';
+            "ppp/chap-secrets" = chap-secrets;
+          };
+        };
+      };
+      client = {config, pkgs, ...}: {
+        services.pppd = {
+          enable = true;
+          peers.test = {
+            config = ''
+              plugin rp-pppoe.so eth1
+              name "flynn"
+              noipdefault
+              persist
+              noauth
+              debug
+            '';
+          };
+        };
+        environment.etc."ppp/chap-secrets" = chap-secrets;
+      };
+    };
+
+    testScript = ''
+      startAll;
+      $client->waitUntilSucceeds("ping -c1 -W1 192.0.2.1");
+      $server->waitUntilSucceeds("ping -c1 -W1 192.0.2.2");
+    '';
+  })