From 66f1d7ee95ba693a15ae5dc413289fee954f0f04 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 22 May 2019 22:56:46 +0200
Subject: [PATCH] Fetch the flake registry from the NixOS/flake-registry repo

---
 flake-registry.json          | 20 --------------------
 local.mk                     |  2 --
 src/libexpr/eval.cc          |  8 --------
 src/libexpr/eval.hh          | 10 +++++-----
 src/libexpr/primops/flake.cc | 16 +++++++++++++---
 src/libexpr/primops/flake.hh |  2 --
 src/nix/flake.cc             |  2 +-
 7 files changed, 19 insertions(+), 41 deletions(-)
 delete mode 100644 flake-registry.json

diff --git a/flake-registry.json b/flake-registry.json
deleted file mode 100644
index 725bcef07..000000000
--- a/flake-registry.json
+++ /dev/null
@@ -1,20 +0,0 @@
-{
-    "flakes": {
-        "dwarffs": {
-            "uri": "github:edolstra/dwarffs/flake"
-        },
-        "nix": {
-            "uri": "github:NixOS/nix/flakes"
-        },
-        "nixpkgs": {
-            "uri": "github:edolstra/nixpkgs/release-19.03"
-        },
-        "hydra": {
-            "uri": "github:NixOS/hydra/flake"
-        },
-        "patchelf": {
-            "uri": "github:NixOS/patchelf"
-        }
-    },
-    "version": 1
-}
diff --git a/local.mk b/local.mk
index 11ed9c0a6..4b380176f 100644
--- a/local.mk
+++ b/local.mk
@@ -10,5 +10,3 @@ GLOBAL_CXXFLAGS += -I . -I src -I src/libutil -I src/libstore -I src/libmain -I
 
 $(foreach i, config.h $(call rwildcard, src/lib*, *.hh), \
   $(eval $(call install-file-in, $(i), $(includedir)/nix, 0644)))
-
-$(eval $(call install-data-in,$(d)/flake-registry.json,$(datadir)/nix))
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 2789ea313..0f8a105b1 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -1978,14 +1978,6 @@ std::ostream & operator << (std::ostream & str, const ExternalValueBase & v) {
 
 EvalSettings evalSettings;
 
-EvalSettings::EvalSettings()
-{
-    if (flakeRegistry == "")
-        // FIXME: static initialization order fiasco. But this will go
-        // away when we switch to an online registry.
-        flakeRegistry = settings.nixDataDir + "/nix/flake-registry.json";
-}
-
 static GlobalConfig::Register r1(&evalSettings);
 
 
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index b0bf777fc..1e45bc1a8 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -325,9 +325,11 @@ public:
 
     const std::vector<std::shared_ptr<FlakeRegistry>> getFlakeRegistries();
 
+    std::shared_ptr<FlakeRegistry> getGlobalFlakeRegistry();
+
 private:
-    std::shared_ptr<FlakeRegistry> _flakeRegistry;
-    std::once_flag _flakeRegistryInit;
+    std::shared_ptr<FlakeRegistry> _globalFlakeRegistry;
+    std::once_flag _globalFlakeRegistryInit;
 };
 
 
@@ -368,10 +370,8 @@ struct EvalSettings : Config
     Setting<Strings> allowedUris{this, {}, "allowed-uris",
         "Prefixes of URIs that builtin functions such as fetchurl and fetchGit are allowed to fetch."};
 
-    Setting<std::string> flakeRegistry{this, "", "flake-registry",
+    Setting<std::string> flakeRegistry{this, "https://raw.githubusercontent.com/NixOS/flake-registry/master/flake-registry.json", "flake-registry",
         "Path or URI of the global flake registry."};
-
-    EvalSettings();
 };
 
 extern EvalSettings evalSettings;
diff --git a/src/libexpr/primops/flake.cc b/src/libexpr/primops/flake.cc
index 9131080bf..c6c380118 100644
--- a/src/libexpr/primops/flake.cc
+++ b/src/libexpr/primops/flake.cc
@@ -131,9 +131,19 @@ void writeLockFile(const LockFile & lockFile, const Path & path)
     writeFile(path, json.dump(4) + "\n"); // '4' = indentation in json file
 }
 
-std::shared_ptr<FlakeRegistry> getGlobalRegistry()
+std::shared_ptr<FlakeRegistry> EvalState::getGlobalFlakeRegistry()
 {
-    return readRegistry(evalSettings.flakeRegistry);
+    std::call_once(_globalFlakeRegistryInit, [&]() {
+        auto path = evalSettings.flakeRegistry;
+
+        if (!hasPrefix(path, "/"))
+            path = getDownloader()->downloadCached(store,
+                evalSettings.flakeRegistry, false, "registry").path;
+
+        _globalFlakeRegistry = readRegistry(path);
+    });
+
+    return _globalFlakeRegistry;
 }
 
 Path getUserRegistryPath()
@@ -162,7 +172,7 @@ const Registries EvalState::getFlakeRegistries()
     Registries registries;
     registries.push_back(getFlagRegistry(registryOverrides));
     registries.push_back(getUserRegistry());
-    registries.push_back(getGlobalRegistry());
+    registries.push_back(getGlobalFlakeRegistry());
     return registries;
 }
 
diff --git a/src/libexpr/primops/flake.hh b/src/libexpr/primops/flake.hh
index 983c0eab6..b965aa9e7 100644
--- a/src/libexpr/primops/flake.hh
+++ b/src/libexpr/primops/flake.hh
@@ -120,8 +120,6 @@ struct NonFlake
         resolvedRef(sourceInfo.resolvedRef), revCount(sourceInfo.revCount), storePath(sourceInfo.storePath) {};
 };
 
-std::shared_ptr<FlakeRegistry> getGlobalRegistry();
-
 Flake getFlake(EvalState &, const FlakeRef &, bool impureIsAllowed);
 
 struct ResolvedFlake
diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index 2dcdfc663..912b154c1 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -298,7 +298,7 @@ struct CmdFlakePin : virtual Args, EvalCommand
             it->second = getFlake(*evalState, it->second, true).resolvedRef;
             writeRegistry(userRegistry, userRegistryPath);
         } else {
-            std::shared_ptr<FlakeRegistry> globalReg = getGlobalRegistry();
+            std::shared_ptr<FlakeRegistry> globalReg = evalState->getGlobalFlakeRegistry();
             it = globalReg->entries.find(FlakeRef(alias));
             if (it != globalReg->entries.end()) {
                 FlakeRef newRef = getFlake(*evalState, it->second, true).resolvedRef;