Add hydraJobs with tests and packages

Reviewed-by: Rodrigo Arias Mallo <rodrigo.arias@bsc.es>
Tested-by: Rodrigo Arias Mallo <rodrigo.arias@bsc.es>

flake.nix

@@ -2,17 +2,23 @@
   inputs.nixpkgs.url = "nixpkgs";
 
   outputs = { self, nixpkgs, ...}:
-  let
-    pkgs = import nixpkgs {
+    let
       # For now we only support x86
       system = "x86_64-linux";
-      overlays = [ self.overlays.default ];
-    };
-  in
+      pkgs = import nixpkgs {
+        inherit system;
+        overlays = [ self.overlays.default ];
+      };
+    in
     {
       bscOverlay = import ./overlay.nix;
       overlays.default = self.bscOverlay;
-      legacyPackages.x86_64-linux = pkgs;
+      # full nixpkgs with our overlay applied
+      legacyPackages.${system} = pkgs;
+
+      hydraJobs = {
+        inherit (self.legacyPackages.${system}.bsc-ci) test pkgs;
+      };
 
       # propagate nixpkgs lib, so we can do bscpkgs.lib
       inherit (nixpkgs) lib;