nixos/frp: use toml configFile

According to upstream, the INI configuration file is deprecated and
TOML/YAML/JSON is recommended.
Link: https://github.com/fatedier/frp/tree/dev#configuration-files

nixos/doc/manual/release-notes/rl-2405.section.md

@@ -67,6 +67,12 @@ The pre-existing [services.ankisyncd](#opt-services.ankisyncd.enable) has been m
 
 - The legacy and long deprecated systemd target `network-interfaces.target` has been removed. Use `network.target` instead.
 
+- `services.frp.settings` now generates the frp configuration file in TOML format as [recommended by upstream](https://github.com/fatedier/frp#configuration-files), instead of the legacy INI format. This has also introduced other changes in the configuration file structure and options.
+  - The `settings.common` section in the configuration is no longer valid and all the options form inside it now goes directly under `settings`.
+  - The `_` separating words in the configuration options is removed so the options are now in camel case. For example: `server_addr` becomes `serverAddr`, `server_port` becomes `serverPort` etc.
+  - Proxies are now defined with a new option `settings.proxies` which takes a list of proxies.
+  - Consult the [upstream documentation](https://github.com/fatedier/frp#example-usage) for more details on the changes.
+
 - `mkosi` was updated to v20. Parts of the user interface have changed. Consult the
   release notes of [v19](https://github.com/systemd/mkosi/releases/tag/v19) and
   [v20](https://github.com/systemd/mkosi/releases/tag/v20) for a list of changes.

nixos/modules/services/networking/frp.nix

@@ -4,8 +4,8 @@ with lib;
 
 let
   cfg = config.services.frp;
-  settingsFormat = pkgs.formats.ini { };
-  configFile = settingsFormat.generate "frp.ini" cfg.settings;
+  settingsFormat = pkgs.formats.toml { };
+  configFile = settingsFormat.generate "frp.toml" cfg.settings;
   isClient = (cfg.role == "client");
   isServer = (cfg.role == "server");
 in
@@ -31,17 +31,13 @@ in
         default = { };
         description = mdDoc ''
           Frp configuration, for configuration options
-          see the example of [client](https://github.com/fatedier/frp/blob/dev/conf/frpc_legacy_full.ini)
-          or [server](https://github.com/fatedier/frp/blob/dev/conf/frps_legacy_full.ini) on github.
-        '';
-        example = literalExpression ''
-          {
-            common = {
-              server_addr = "x.x.x.x";
-              server_port = 7000;
-            };
-          }
+          see the example of [client](https://github.com/fatedier/frp/blob/dev/conf/frpc_full_example.toml)
+          or [server](https://github.com/fatedier/frp/blob/dev/conf/frps_full_example.toml) on github.
         '';
+        example = {
+            serverAddr = "x.x.x.x";
+            serverPort = 7000;
+          };
       };
     };
   };
@@ -62,7 +58,7 @@ in
             Type = "simple";
             Restart = "on-failure";
             RestartSec = 15;
-            ExecStart = "${cfg.package}/bin/${executableFile} -c ${configFile}";
+            ExecStart = "${cfg.package}/bin/${executableFile} --strict_config -c ${configFile}";
             StateDirectoryMode = optionalString isServer "0700";
             DynamicUser = true;
             # Hardening

nixos/tests/frp.nix

@@ -18,10 +18,8 @@ import ./make-test-python.nix ({ pkgs, lib, ... }: {
         enable = true;
         role = "server";
         settings = {
-          common = {
-            bind_port = 7000;
-            vhost_http_port = 80;
-          };
+          bindPort = 7000;
+          vhostHTTPPort = 80;
         };
       };
     };
@@ -59,15 +57,16 @@ import ./make-test-python.nix ({ pkgs, lib, ... }: {
         enable = true;
         role = "client";
         settings = {
-          common = {
-            server_addr = "10.0.0.1";
-            server_port = 7000;
-          };
-          web = {
-            type = "http";
-            local_port = 80;
-            custom_domains = "10.0.0.1";
-          };
+          serverAddr = "10.0.0.1";
+          serverPort = 7000;
+          proxies = [
+            {
+              name = "web";
+              type = "http";
+              localPort = 80;
+              customDomains = [ "10.0.0.1" ];
+            }
+          ];
         };
       };
     };