Use nixpkgs from flake.lock and support attrs when importing bscpkgs

This makes `nix-build` and friends use the current flake lock instead of
the outdated pinned version we had in `./nixpkgs.nix`

With this, `nix-build -A ovni` and `nix build .#ovni` will produce the
same result.

This will fail if the flake nixpkgs input does not come from NixOS/nixpkgs.
We could use edolstra/flake-compat instead, but it's overkill imho.

Additionally, I made default.nix behave like nixpkgs, so that we can
import bscpkgs à la nixpkgs (Apply overlays and other options that nixpkgs
accepts): `import bscpkgs { overlays = [ <...> ]; }`

default.nix

@@ -1,11 +1,19 @@
 let
   bscOverlay = import ./overlay.nix;
 
-  # Pin the nixpkgs
-  nixpkgsPath = import ./nixpkgs.nix;
-
-  pkgs = import nixpkgsPath {
-    overlays = [ bscOverlay ];
+  # read flake.lock and determine revision from there
+  lock = builtins.fromJSON (builtins.readFile ./flake.lock);
+  inherit (lock.nodes.nixpkgs.locked) rev narHash;
+  fetchedNixpkgs = builtins.fetchTarball {
+    url = "https://github.com/NixOS/nixpkgs/archive/${rev}.tar.gz";
+    sha256 = narHash;
   };
-
-in pkgs
+in
+{ overlays ? [ ]
+, nixpkgs ? fetchedNixpkgs
+, ...
+}@attrs:
+import nixpkgs (
+  (builtins.removeAttrs attrs [ "overlays" "nixpkgs" ]) //
+  { overlays = [ bscOverlay ] ++ overlays; }
+)

flake.nix

@@ -13,5 +13,9 @@
       bscOverlay = import ./overlay.nix;
       overlays.default = self.bscOverlay;
       legacyPackages.x86_64-linux = pkgs;
+
+      hydraJobs = {
+        inherit (pkgs) bsc-ci;
+      };
     };
 }

nixpkgs.nix

@@ -1,9 +0,0 @@
-let
-  commit = "e4ad989506ec7d71f7302cc3067abd82730a4beb";
-in builtins.fetchTarball {
-    # Descriptive name to make the store path easier to identify
-    name = "nixpkgs-${commit}";
-    url = "https://github.com/nixos/nixpkgs/archive/${commit}.tar.gz";
-    # Hash obtained using `nix-prefetch-url --unpack <url>`
-    sha256 = "sha256-de9KYi8rSJpqvBfNwscWdalIJXPo8NjdIZcEJum1mH0=";
-}

pkgs/bench6/default.nix

@@ -7,7 +7,7 @@
 , mpi
 , tampi
 , gitBranch ? "master"
-, gitURL ? "ssh://git@bscpm03.bsc.es/rarias/bench6.git"
+, gitURL ? "ssh://git@bscpm04.bsc.es/rarias/bench6.git"
 , gitCommit ? "1e6ce2aa8ad7b4eef38df1581d7ec48a8815f85d"
 }:
 

pkgs/cn6/default.nix

@@ -28,7 +28,7 @@ stdenv.mkDerivation rec {
   ] ++ optionals (enableTest) [ mpi clangOmpss2 tampi ];
 
   src = builtins.fetchGit {
-    url = "ssh://git@bscpm03.bsc.es/rarias/cn6.git";
+    url = "ssh://git@bscpm04.bsc.es/rarias/cn6.git";
     ref = "master";
     rev = "c72c3b66b720c2a33950f536fc819051c8f20a69";
   };

pkgs/llvm-ompss2/clang.nix

@@ -14,7 +14,7 @@
 , gcc # needed to set the rpath of libstdc++ for clang-tblgen
 , enableDebug ? false
 , useGit ? false
-, gitUrl ? "ssh://git@bscpm03.bsc.es/llvm-ompss/llvm-mono.git"
+, gitUrl ? "ssh://git@bscpm04.bsc.es/llvm-ompss/llvm-mono.git"
 , gitBranch ? "master"
 , gitCommit ? "8c0d267c04d7fc3fb923078f510fcd5f4719a6cc"
 }:

pkgs/mcxx/git.nix

@@ -23,7 +23,7 @@ stdenv.mkDerivation rec {
   };
 
   src = builtins.fetchGit {
-    url = "ssh://git@bscpm03.bsc.es/mercurium/mcxx";
+    url = "ssh://git@bscpm04.bsc.es/mercurium/mcxx";
     ref = "master";
   };
 

pkgs/mcxx/rarias.nix

@@ -19,7 +19,7 @@ stdenv.mkDerivation rec {
 
   #src = /home/Computational/rarias/mcxx;
   src = builtins.fetchGit {
-    url = "ssh://git@bscpm03.bsc.es/rarias/mcxx";
+    url = "ssh://git@bscpm04.bsc.es/rarias/mcxx";
     rev = "44129a6ac05b8f78b06e9e2eff71438b5ca4d29f";
   };
 

pkgs/nanos6/default.nix

@@ -17,7 +17,7 @@
 , cachelineBytes ? 64
 , enableGlibcxxDebug ? false
 , useGit ? false
-, gitUrl ? "ssh://git@bscpm03.bsc.es/nanos6/nanos6"
+, gitUrl ? "ssh://git@bscpm04.bsc.es/nanos6/nanos6"
 , gitBranch ? "master"
 , gitCommit ? "9f54c988e0a8b9c011d9d526acdb8d76f18fcae4"
 }:

pkgs/nixtools/default.nix

@@ -7,7 +7,7 @@ stdenv.mkDerivation rec {
   pname = "nixtools";
   version = "${src.shortRev}";
   src = builtins.fetchGit {
-    url = "ssh://git@bscpm03.bsc.es/rarias/nixtools";
+    url = "ssh://git@bscpm04.bsc.es/rarias/nixtools";
     ref = "master";
     rev = "a103e392048ace3ed88ce74648b32c9e6ed094da";
   };

pkgs/ovni/default.nix

@@ -6,7 +6,7 @@
 , fetchFromGitHub
 , useGit ? false
 , gitBranch ? "master"
-, gitUrl ? "ssh://git@bscpm03.bsc.es/rarias/ovni.git"
+, gitUrl ? "ssh://git@bscpm04.bsc.es/rarias/ovni.git"
 , gitCommit ? "a7103f8510d1ec124c3e01ceb47d1e443e98bbf4"
 , enableDebug ? false
 # Only enable MPI if the build is native (fails on cross-compilation)

pkgs/tampi/default.nix

@@ -13,7 +13,7 @@
 , enableOvni ? true
 , ovni ? null
 , useGit ? false
-, gitUrl ? "ssh://git@bscpm03.bsc.es/interoperability/tampi.git"
+, gitUrl ? "ssh://git@bscpm04.bsc.es/interoperability/tampi.git"
 , gitBranch ? "master"
 , gitCommit ? "a5c93bf8ab045b71ad4a8d5e2c991ce774db5cbc"
 }: