syncstorage-rs: split into syncstorage-rs-{mysql,pgsql}

Expose both database backends as top-level packages so Hydra builds
and caches each variant. The firefox-syncserver module now picks the
appropriate package based on `services.firefox-syncserver.database.type`
when the user does not supply one explicitly.

The `package` option becomes `nullOr package` with a `null` default;
this avoids requiring a user-supplied custom package to implement the
`dbBackend` override attribute.

Author: Titaniumtown

nixos/modules/services/networking/firefox-syncserver.nix

@@ -27,7 +27,13 @@ let
   # where the syncserver starts before its database and role exist.
   dbService = if dbIsMySQL then "mysql.service" else "postgresql.target";
 
-  syncserver = cfg.package.override { dbBackend = cfg.database.type; };
+  syncserver =
+    if cfg.package != null then
+      cfg.package
+    else if dbIsMySQL then
+      pkgs.syncstorage-rs-mysql
+    else
+      pkgs.syncstorage-rs-pgsql;
 
   format = pkgs.formats.toml { };
   settings = {
@@ -139,7 +145,20 @@ in
         {option}`${opt.singleNode.enable}` does this automatically when enabled
       '';
 
-      package = lib.mkPackageOption pkgs "syncstorage-rs" { };
+      package = lib.mkOption {
+        type = lib.types.nullOr lib.types.package;
+        default = null;
+        defaultText = lib.literalExpression ''
+          if config.${opt.database.type} == "mysql" then
+            pkgs.syncstorage-rs-mysql
+          else
+            pkgs.syncstorage-rs-pgsql
+        '';
+        description = ''
+          Syncstorage server package to use. When `null`, the package is
+          selected automatically based on {option}`${opt.database.type}`.
+        '';
+      };
 
       database.type = lib.mkOption {
         type = lib.types.enum [

pkgs/by-name/sy/syncstorage-rs/package.nix

@@ -84,7 +84,10 @@ rustPlatform.buildRustPackage (finalAttrs: {
 
   passthru.updateScript = nix-update-script { };
 
-  passthru.tests = { inherit (nixosTests) firefox-syncserver; };
+  passthru.tests = {
+    firefox-syncserver =
+      nixosTests.firefox-syncserver.${if dbBackend == "postgresql" then "postgresql" else "mysql"};
+  };
 
   meta = {
     description = "Mozilla Sync Storage built with Rust";

pkgs/top-level/all-packages.nix

@@ -10336,6 +10336,13 @@ with pkgs;
     waylandSupport = true;
   };
 
+  syncstorage-rs-mysql = callPackage ../by-name/sy/syncstorage-rs/package.nix {
+    dbBackend = "mysql";
+  };
+  syncstorage-rs-pgsql = callPackage ../by-name/sy/syncstorage-rs/package.nix {
+    dbBackend = "postgresql";
+  };
+
   inherit
     (callPackages ../applications/networking/syncthing {
       inherit (darwin) autoSignDarwinBinariesHook;