make nixos module hydra from this repository by default

When people reach out to the git repository they probably want to use
hydra from the same source.
This also removes the need for an overlay with simpler and more
performant direct use of the nixpkgs passed in. Before it was
re-importing nixpkgs.

test

flake.nix

@@ -9,14 +9,6 @@
     let
       systems = [ "x86_64-linux" "aarch64-linux" ];
       forEachSystem = nixpkgs.lib.genAttrs systems;
-
-      overlayList = [ self.overlays.default nix.overlays.default ];
-
-      pkgsBySystem = forEachSystem (system: import nixpkgs {
-        inherit system;
-        overlays = overlayList;
-      });
-
     in
     rec {
 
@@ -30,7 +22,6 @@
       };
 
       hydraJobs = {
-
         build = forEachSystem (system: packages.${system}.hydra);
 
         buildNoTests = forEachSystem (system:
@@ -39,19 +30,21 @@
           })
         );
 
-        manual = forEachSystem (system:
+        manual = forEachSystem (system: let
-          let pkgs = pkgsBySystem.${system}; in
+          pkgs = nixpkgs.legacyPackages.${system};
-          pkgs.runCommand "hydra-manual-${pkgs.hydra.version}" { }
+          hydra = self.packages.${pkgs.hostPlatform.system}.hydra;
+        in
+          pkgs.runCommand "hydra-manual-${hydra.version}" { }
             ''
               mkdir -p $out/share
-              cp -prvd ${pkgs.hydra}/share/doc $out/share/
+              cp -prvd ${hydra}/share/doc $out/share/
 
               mkdir $out/nix-support
               echo "doc manual $out/share/doc/hydra" >> $out/nix-support/hydra-build-products
             '');
 
         tests = import ./nixos-tests.nix {
-          inherit forEachSystem nixpkgs pkgsBySystem nixosModules;
+          inherit forEachSystem nixpkgs nixosModules;
         };
 
         container = nixosConfigurations.container.config.system.build.toplevel;
@@ -64,12 +57,17 @@
       });
 
       packages = forEachSystem (system: {
-        hydra = pkgsBySystem.${system}.hydra;
+        hydra = nixpkgs.legacyPackages.${system}.callPackage ./package.nix {
-        default = pkgsBySystem.${system}.hydra;
+          inherit (nixpkgs.lib) fileset;
+          rawSrc = self;
+          nix = nix.packages.${system}.nix;
+          nix-perl-bindings = nix.hydraJobs.perlBindings.${system};
+        };
+        default = self.packages.${system}.hydra;
       });
 
       nixosModules = import ./nixos-modules {
-        overlays = overlayList;
+        inherit self;
       };
 
       nixosConfigurations.container = nixpkgs.lib.nixosSystem {
@@ -77,7 +75,6 @@
         modules =
           [
             self.nixosModules.hydra
-            self.nixosModules.overlayNixpkgsForThisHydra
             self.nixosModules.hydraTest
             self.nixosModules.hydraProxy
             {

nixos-modules/default.nix

@@ -1,11 +1,10 @@
-{ overlays }:
+{ self }:
 
 {
-  hydra = import ./hydra.nix;
+  hydra = { pkgs, lib,... }: {
-
+    _file = ./default.nix;
-  overlayNixpkgsForThisHydra = { pkgs, ... }: {
+    imports = [ ./hydra.nix ];
-    nixpkgs = { inherit overlays; };
+    services.hydra-dev.package = lib.mkDefault self.packages.${pkgs.hostPlatform.system}.hydra;
-    services.hydra.package = pkgs.hydra;
   };
 
   hydraTest = { pkgs, ... }: {

nixos-modules/hydra.nix

@@ -68,8 +68,6 @@ in
 
       package = mkOption {
         type = types.path;
-        default = pkgs.hydra;
-        defaultText = literalExpression "pkgs.hydra";
         description = "The Hydra package.";
       };
 

nixos-tests.nix

@@ -1,13 +1,12 @@
-{ forEachSystem, nixpkgs, pkgsBySystem, nixosModules }:
+{ forEachSystem, nixpkgs, nixosModules }:
 
 let
   # NixOS configuration used for VM tests.
   hydraServer =
-    { config, pkgs, ... }:
+    { pkgs, ... }:
     {
       imports = [
         nixosModules.hydra
-        nixosModules.overlayNixpkgsForThisHydra
         nixosModules.hydraTest
       ];
 
@@ -44,11 +43,10 @@ in
     });
 
   notifications = forEachSystem (system:
-    let pkgs = pkgsBySystem.${system}; in
     with import (nixpkgs + "/nixos/lib/testing-python.nix") { inherit system; };
     simpleTest {
       name = "hydra-notifications";
-      nodes.machine = { pkgs, ... }: {
+      nodes.machine = {
         imports = [ hydraServer ];
         services.hydra-dev.extraConfig = ''
           <influxdb>
@@ -89,7 +87,7 @@ in
 
         # Setup the project and jobset
         machine.succeed(
-            "su - hydra -c 'perl -I ${pkgs.hydra.perlDeps}/lib/perl5/site_perl ${./t/setup-notifications-jobset.pl}' >&2"
+            "su - hydra -c 'perl -I ${config.services.hydra-dev.package.perlDeps}/lib/perl5/site_perl ${./t/setup-notifications-jobset.pl}' >&2"
         )
 
         # Wait until hydra has build the job and
@@ -103,7 +101,7 @@ in
     });
 
   gitea = forEachSystem (system:
-    let pkgs = pkgsBySystem.${system}; in
+    let pkgs = nixpkgs.legacyPackages.${system}; in
     with import (nixpkgs + "/nixos/lib/testing-python.nix") { inherit system; };
     makeTest {
       name = "hydra-gitea";
@@ -298,7 +296,7 @@ in
     });
 
   validate-openapi = forEachSystem (system:
-    let pkgs = pkgsBySystem.${system}; in
+    let pkgs = nixpkgs.legacyPackages.${system}; in
     pkgs.runCommand "validate-openapi"
     { buildInputs = [ pkgs.openapi-generator-cli ]; }
     ''