modules/socketActivation: misc improvement

modules/socketActivation.nix

@@ -1,19 +1,18 @@
-{ config, pkgs, lib, ... }:
+{ options, config, pkgs, lib, ... }:
 let
   inherit (lib) mkOption types mdDoc;
-  cfg = lib.filterAttrs (_: value: value.enable) config.local.socketActivation;
 in
 {
-  options.local.socketActivation = mkOption {
+  options.socketActivation = mkOption {
     type = types.attrsOf (types.submodule ({ name, ... }: {
       options = {
-        enable = lib.mkEnableOption "socket activation for <name>";
+        enable = lib.mkEnableOption "socket activation for a systemd service";
 
         service = mkOption {
           type = types.str;
           default = name;
           defaultText = "<name>";
-          example = "myservice";
+          example = "gitea";
           description = mdDoc "Systemd service name";
         };
 
@@ -23,7 +22,6 @@ in
           example = false;
           description = mdDoc ''
             Whether to isolate the network of the original service.
-
             This is recommended, but might be impractical if the original
             service also uses networking for its own operation.
           '';
@@ -34,29 +32,28 @@ in
           example = "localhost:8080";
           description = mdDoc ''
             Socket that the original service is listening to.
-
-            This could be a TCP or UNIX socket.
+            This could be an INET/6 or UNIX socket.
           '';
         };
 
         newSocketAddress = mkOption {
           type = with types; either str port;
+          default = "/run/${name}.socket";
+          defaultText = "/run/<name>.socket";
           example = "localhost:8080";
           description = mdDoc ''
-            Addres of the new systemd socket.
-
-            This could be a TCP or UNIX socket.
+            Address of the new systemd socket.
+            This could be an INET/6 or UNIX socket.
           '';
         };
 
         connectionsMax = mkOption {
-          type = types.int;
+          type = types.ints.unsigned;
           default = 256;
           example = 1024;
           description = mdDoc ''
             Sets the maximum number of simultaneous connections.
             If the limit of concurrent connections is reached further connections will be refused.
-
             See <https://www.freedesktop.org/software/systemd/man/systemd-socket-proxyd.html#--connections-max=>
           '';
         };
@@ -68,38 +65,87 @@ in
           description = mdDoc ''
             Amount of inactivity time, before systemd shuts down the service.
             If this is set to `null`, the service will never stop.
-
             See <https://www.freedesktop.org/software/systemd/man/systemd-socket-proxyd.html#--exit-idle-time=>
           '';
         };
+
+        openFirewall = mkOption {
+          type = types.bool;
+          default = false;
+          example = true;
+          description = mdDoc ''
+            Whether to open the firewall for {var}`newSocketAddress`
+          '';
+        };
+
+        createNginxUpstream = mkOption {
+          type = types.bool;
+          default = true;
+          example = false;
+          description = mdDoc ''
+            Whether to create an http upstream entry for {var}`newSocketAddress` in nginx.
+            See <https://nginx.org/en/docs/http/ngx_http_upstream_module.html#upstream>
+          '';
+        };
+
+        extraSocketConfig = mkOption {
+          type = types.attrs; # TODO: not exactly sure how to type this,
+                              #       maybe reexposing this through the module is a bad idea?
+          default = { };
+          example = {
+            KeepAlive = true;
+            MaxConnectionsPerSource = 3;
+            Priority = 2;
+          };
+          description = mdDoc ''
+            Extra configuration to go into the [socket] section of the systemd unit.
+            See <https://www.freedesktop.org/software/systemd/man/latest/systemd.socket.html>
+          '';
+        };
       };
     }));
-    description = mdDoc "Forcefully socket activated systemd services";
+    description = mdDoc "Socket activated services using {command}`systemd-socket-proxyd`.";
     default = { };
   };
 
-  config = {
-    assertions = lib.mapAttrsToList (name: value: {
-      # NOTE: This assertion is missing a lot of invalid cases.
-      #       The original socket address could've been "localhost:1234" and now only 1234,
+  config = let
+    activeServices = lib.filterAttrs (_: value: value.enable) config.socketActivation;
+    foreachService = f: lib.mapAttrsToList f activeServices;
+  in {
+    assertions = foreachService (name: value: {
+      # NOTE: This assertion is just covering for the most basic invalid usecases, but misses a lot.
+      #       The original socket address could've been "localhost:1234" and now only "1234",
       #         while still meaning the same thing.
-      #       Also, if the originalSocketAddress and newSocketAddress is the same UNIX socket path
-      #         it doesn't matter whether they're in different namespaces AFAIK, they'll still clash.
-      assertion = !value.privateNamespace -> (value.originalSocketAddress != value.newSocketAddress);
+      assertion = lib.any (b: b) [
+        value.privateNamespace
+        # If this is a UNIX socket, the paths themself
+        # would clash even if in a private namespace
+        (lib.hasPrefix "/" value.originalSocketAddress)
+        (lib.hasPrefix "@" value.originalSocketAddress)
+      ] -> (value.originalSocketAddress != value.newSocketAddress);
       message = ''
-        The new proxied socket address of "${name}" clashes with its original socket address.
-        Either enable `privateNamespace` to isolate the original service' network, or use a separate
-          socket address.
+        The new proxied socket of "${name}" has a new socket address of "${toString value.newSocketAddress}",
+        which clashes with its original address of "${toString value.originalSocketAddress}".
+        Either enable privateNamespace to isolate the original service' network, or use a separate socket address.
       '';
-    }) cfg;
+    });
 
-    systemd = lib.mkMerge ((lib.flip lib.mapAttrsToList) cfg (name: value: let
+    services.nginx.upstreams = let
+      servicesWithNginxUpstream = lib.filterAttrs (_: value: value.createNginxUpstream) activeServices;
+    in lib.mapAttrsToList (name: value: let
+      protocol = if lib.any (p: lib.hasPrefix p value.newSocketAddress) [ "/" "@" ]  then "unix" else "http";
+    in {
+      ${name}.servers."${protocol}:${value.newSocketAddress}" = { };
+    }) servicesWithNginxUpstream;
+
+    systemd = lib.mkMerge (foreachService (name: value: let
       originalService = config.systemd.services.${value.service};
     in {
       sockets."${name}-proxy" = {
         wantedBy = [ "sockets.target" ];
         socketConfig = {
           ListenStream = value.newSocketAddress;
+          MaxConnections = value.connectionsMax;
         };
       };
 
@@ -110,9 +156,7 @@ in
         ];
         after = requires;
 
-        unitConfig = lib.mkIf value.privateNamespace {
-          JoinsNamespaceOf = "${value.service}.service";
-        };
+        unitConfig.JoinsNamespaceOf = lib.mkIf value.privateNamespace "${value.service}.service";
 
         serviceConfig = {
           ExecStart = let
@@ -120,7 +164,7 @@ in
               exit-idle-time = if value.exitIdleTime != null then value.exitIdleTime else "infinity";
               connections-max = value.connectionsMax;
             };
-          in ''${pkgs.systemd}/lib/systemd/systemd-socket-proxyd ${args} "${cfg.${name}.originalSocketAddress}"'';
+          in ''${pkgs.systemd}/lib/systemd/systemd-socket-proxyd ${args} "${value.originalSocketAddress}"'';
 
           CapabilityBoundingSet = "";
           LockPersonality = true;
@@ -171,4 +215,6 @@ in
       };
     }));
   };
+
+  meta.maintainers = with lib.maintainers; [ h7x4 ];
 }