From 5d3680d26516b35a04cd02b6e95122c46bd243a5 Mon Sep 17 00:00:00 2001
From: Gleb Peregud <gleber.p@gmail.com>
Date: Fri, 11 Dec 2015 00:00:33 +0100
Subject: [PATCH] Fetch hex.pm registry snapshot with external github repo.

This allows to avoid fetching registry file from S3 at build time,
making the build hermetic and much faster. Automatic tools will be used
to update said external repo content when Hex packages are
imported/update.
---
 pkgs/development/erlang-modules/build-hex.nix | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/pkgs/development/erlang-modules/build-hex.nix b/pkgs/development/erlang-modules/build-hex.nix
index e664d357d851..efeda1c6373c 100644
--- a/pkgs/development/erlang-modules/build-hex.nix
+++ b/pkgs/development/erlang-modules/build-hex.nix
@@ -1,4 +1,4 @@
-{ stdenv, erlang, rebar3, openssl, libyaml, fetchurl }:
+{ stdenv, erlang, rebar3, openssl, libyaml, fetchurl, fetchFromGitHub }:
 
 { name, version, sha256
 , hexPkg ? name
@@ -14,7 +14,14 @@ stdenv.mkDerivation (attrs // {
 
   buildInputs = buildInputs ++ [ erlang rebar3 openssl libyaml ];
 
-  postPatch = ''
+  postPatch = let
+    registrySnapshot = fetchFromGitHub {
+      owner = "gleber";
+      repo = "hex-pm-registry-snapshots";
+      rev = "48147b0";
+      sha256 = "0ibfnhrhbka4n6wkhs99fpy3sjab54ip37jgvx2hcfhfr4pxhbxw";
+    };
+  in ''
     rm -f rebar rebar3
     if [ -e "src/${name}.app.src" ]; then
       sed -i -e 's/{ *vsn *,[^}]*}/{vsn, "${version}"}/' "src/${name}.app.src"
@@ -25,6 +32,9 @@ stdenv.mkDerivation (attrs // {
     echo "{plugins, [pc]}." >> rebar.config
     '' else ''''}
 
+    mkdir -p _build/default/{lib,plugins}/ ./.cache/rebar3/hex/default/
+    zcat ${registrySnapshot}/registry.ets.gz > .cache/rebar3/hex/default/registry
+
     ${postPatch}
   '';
 
@@ -44,7 +54,6 @@ stdenv.mkDerivation (attrs // {
     };
   in ''
     runHook preConfigure
-    mkdir -p _build/default/{lib,plugins}/
     ${concatMapStrings (dep: ''
       header "linking erlang dependency ${dep}"
       ln -s "${dep}" "_build/default/lib/${dep.packageName}"
@@ -62,7 +71,7 @@ stdenv.mkDerivation (attrs // {
   # this hermetic
   buildPhase = ''
     runHook preBuild
-    HOME=. rebar3 do update, compile
+    HOME=. rebar3 compile
     ${if compilePorts then ''
     HOME=. rebar3 pc compile
     '' else ''''}