flake.nix: wrap hydraJobs to enable hydra-build-products

makes these files downloadable through the Hydra web interface

flake.nix

@@ -53,5 +53,37 @@
 
       # For `nix flake check`, and Hydra
       checks = self.packages;
+
+      hydraJobs =
+        with self.lib;
+        let
+          exportFileWrapper = pkg:
+            hydraJob (
+              nixpkgs.legacyPackages.${system}.runCommand "${pkg.name}-exported" {
+                src = pkg;
+              } ''
+                NAME="${pkg.name}"
+                mkdir -p $out/nix-support
+                ln -s ${pkg} $out/$NAME
+                echo file source-dist $out/$NAME >> $out/nix-support/hydra-build-products
+              ''
+            );
+          wrappers = {
+            "all-device-scripts" = pkg:
+              hydraJob pkg;
+
+            "export-config" = exportFileWrapper;
+            ".*-pillar" = exportFileWrapper;
+            "switch-.*" = exportFileWrapper;
+            "ap.*" = exportFileWrapper;
+          };
+        in
+          builtins.mapAttrs (name: pkg:
+            builtins.foldl' (result: wrapperName:
+              if builtins.match wrapperName name != null
+              then wrappers.${wrapperName} pkg
+              else result
+            ) pkg (builtins.attrNames wrappers)
+          ) self.packages.${system};
     };
 }