set up a config for forgejo

configs/services/forgejo.nix

@@ -0,0 +1,42 @@
+{ lib, pkgs, config, ... }:
+let
+  dbname = "forgejo";
+  ssh_port = 2000;
+in
+{
+
+  # enable and configure forgejo
+  services.forgejo = {
+    enable = true;
+    database = {
+      type = "postgres";
+      name = dbname;
+    };
+
+    settings = {
+      server = {
+        DOMAIN = "192.168.178.50";
+        SSH_PORT = ssh_port;
+        # important because otherwise ssh doesn't seem to work…
+        START_SSH_SERVER = true;
+        BUILTIN_SSH_SERVER_USER = "git";
+      };
+      cache = {
+        ADAPTER = "twoqueue";
+        HOST = "{\"size\":100, \"recent_ratio\":0.25, \"ghost_ratio\":0.5}";
+      };
+      service.DISABLE_REGISTRATION = true;
+      repository.USE_COMPAT_SSH_URI = true;
+      security.LOGIN_REMEMBER_DAYS = 365;
+    };
+  };
+
+  # enable a PostgreSQL DB for forgejo
+  services.postgresql = {
+    enable = true;
+    ensureDatabases = [ dbname ];
+  };
+
+  networking.firewall.allowedTCPPorts = [ 3000 ssh_port ];
+
+}