Use nixpkgs pinning from common iohk-nix repo

Author: rvl

default.nix

@@ -1,7 +1,7 @@
-let localLib = import ./nix/lib.nix; in
 { config ? {}
 , system ? builtins.currentSystem
-, pkgs ? localLib.importPkgs { inherit config system; }
+, iohkLib ? import ./nix/iohk-common.nix { inherit config system; }
+, pkgs ? iohkLib.cardano-sl.pkgs
 }:
 
 import ./nix/pkgs.nix { inherit pkgs; }

nix/fetch-nixpkgs.nix

@@ -0,0 +1,15 @@
+# Imports the iohk-nix library.
+# The version can be overridden for debugging purposes by setting
+# NIX_PATH=iohk_nix=/path/to/iohk-nix
+
+import (
+  let try = builtins.tryEval <iohk_nix>;
+  in if try.success
+  then builtins.trace "using host <iohk_nix>" try.value
+  else
+    let
+      spec = builtins.fromJSON (builtins.readFile ./iohk-nix.json);
+    in builtins.fetchTarball {
+      url = "${spec.url}/archive/${spec.rev}.tar.gz";
+      inherit (spec) sha256;
+    })

nix/iohk-common.nix

@@ -0,0 +1,7 @@
+{
+  "url": "https://github.com/input-output-hk/iohk-nix",
+  "rev": "aa9911a864100ec116b8cbd1bd7f4958dad23acf",
+  "date": "2018-11-14T11:13:03+10:00",
+  "sha256": "1j25vbcwybnbjijr4wdgbgnq47rlfhyk07gwcahvcz53j3ha9xcb",
+  "fetchSubmodules": false
+}

nix/iohk-nix.json

@@ -1,9 +1,5 @@
 #!/usr/bin/env bash
 
-# build (if needed) the nix-tools from the given hash
-NIX_TOOLS=$(nix-build https://github.com/angerman/nix-tools/archive/9b1066f5613b35037231cf2dbb6db25cb60c4205.tar.gz -A nix-tools-all-execs -j8 --no-out-link)
-export PATH=$NIX_TOOLS/bin:$PATH
+set -euo pipefail
 
-# stack-to-nix will transform the stack.yaml file into something
-# nix can understand.
-stack-to-nix -o nix stack.yaml > nix/.stack-pkgs.nix
+exec $(nix-build `dirname $0`/iohk-common.nix -A cardano-sl.regeneratePackages --no-out-link)