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Substitute flake inputs

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This improves reproducibility and may be faster than fetching from the
original source (especially for git/hg inputs, but probably also for
github inputs - our binary cache is probably faster than GitHub's
dynamically generated tarballs).

Unfortunately this doesn't work for the top-level flake since even if
we know the NAR hash of the tree, we don't know the other tree
attributes such as revCount and lastModified.

Fixes #3253.
This commit is contained in:
Eelco Dolstra 2020-02-02 12:41:23 +01:00
parent fad9faf354
commit 94a94da075
No known key found for this signature in database
GPG key ID: 8170B4726D7198DE
2 changed files with 85 additions and 56 deletions
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140
src/libexpr/flake/flake.cc
View file

@ -18,13 +18,13 @@ namespace flake {
/* If 'allowLookup' is true, then resolve 'flakeRef' using the
registries. */
static FlakeRef maybeLookupFlake(
EvalState & state,
ref<Store> store,
const FlakeRef & flakeRef,
bool allowLookup)
{
if (!flakeRef.input->isDirect()) {
if (allowLookup)
return flakeRef.resolve(state.store);
return flakeRef.resolve(store);
else
throw Error("'%s' is an indirect flake reference, but registry lookups are not allowed", flakeRef);
} else
@ -49,6 +49,64 @@ static FlakeRef lookupInFlakeCache(
return flakeRef;
}
static std::pair<fetchers::Tree, FlakeRef> fetchOrSubstituteTree(
EvalState & state,
const FlakeRef & originalRef,
std::optional<TreeInfo> treeInfo,
bool allowLookup,
FlakeCache & flakeCache)
{
/* The tree may already be in the Nix store, or it could be
substituted (which is often faster than fetching from the
original source). So check that. */
if (treeInfo && originalRef.input->isDirect() && originalRef.input->isImmutable()) {
try {
auto storePath = treeInfo->computeStorePath(*state.store);
state.store->ensurePath(storePath);
debug("using substituted/cached input '%s' in '%s'",
originalRef, state.store->printStorePath(storePath));
auto actualPath = state.store->toRealPath(storePath);
if (state.allowedPaths)
state.allowedPaths->insert(actualPath);
return {
Tree {
.actualPath = actualPath,
.storePath = std::move(storePath),
.info = *treeInfo,
},
originalRef
};
} catch (Error & e) {
debug("substitution of input '%s' failed: %s", originalRef, e.what());
}
}
auto resolvedRef = lookupInFlakeCache(flakeCache,
maybeLookupFlake(state.store,
lookupInFlakeCache(flakeCache, originalRef), allowLookup));
auto [tree, lockedRef] = resolvedRef.fetchTree(state.store);
debug("got tree '%s' from '%s'",
state.store->printStorePath(tree.storePath), lockedRef);
flakeCache.push_back({originalRef, lockedRef});
flakeCache.push_back({resolvedRef, lockedRef});
if (state.allowedPaths)
state.allowedPaths->insert(tree.actualPath);
if (treeInfo)
assert(tree.storePath == treeInfo->computeStorePath(*state.store));
return {std::move(tree), lockedRef};
}
static void expectType(EvalState & state, ValueType type,
Value & value, const Pos & pos)
{
@ -143,23 +201,15 @@ static std::map<FlakeId, FlakeInput> parseFlakeInputs(
return inputs;
}
static Flake getFlake(EvalState & state, const FlakeRef & originalRef,
bool allowLookup, FlakeCache & flakeCache)
static Flake getFlake(
EvalState & state,
const FlakeRef & originalRef,
std::optional<TreeInfo> treeInfo,
bool allowLookup,
FlakeCache & flakeCache)
{
auto flakeRef = lookupInFlakeCache(flakeCache,
maybeLookupFlake(state,
lookupInFlakeCache(flakeCache, originalRef), allowLookup));
auto [sourceInfo, lockedRef] = flakeRef.fetchTree(state.store);
debug("got flake source '%s' from '%s'",
state.store->printStorePath(sourceInfo.storePath), lockedRef);
flakeCache.push_back({originalRef, lockedRef});
flakeCache.push_back({flakeRef, lockedRef});
if (state.allowedPaths)
state.allowedPaths->insert(sourceInfo.actualPath);
auto [sourceInfo, lockedRef] = fetchOrSubstituteTree(
state, originalRef, treeInfo, allowLookup, flakeCache);
// Guard against symlink attacks.
auto flakeFile = canonPath(sourceInfo.actualPath + "/" + lockedRef.subdir + "/flake.nix");
@ -192,11 +242,11 @@ static Flake getFlake(EvalState & state, const FlakeRef & originalRef,
expectType(state, tInt, *(**edition).value, *(**edition).pos);
flake.edition = (**edition).value->integer;
if (flake.edition > 201909)
throw Error("flake '%s' requires unsupported edition %d; please upgrade Nix", flakeRef, flake.edition);
throw Error("flake '%s' requires unsupported edition %d; please upgrade Nix", lockedRef, flake.edition);
if (flake.edition < 201909)
throw Error("flake '%s' has illegal edition %d", flakeRef, flake.edition);
throw Error("flake '%s' has illegal edition %d", lockedRef, flake.edition);
} else
throw Error("flake '%s' lacks attribute 'edition'", flakeRef);
throw Error("flake '%s' lacks attribute 'edition'", lockedRef);
if (auto description = vInfo.attrs->get(state.sDescription)) {
expectType(state, tString, *(**description).value, *(**description).pos);
@ -224,7 +274,7 @@ static Flake getFlake(EvalState & state, const FlakeRef & originalRef,
}
} else
throw Error("flake '%s' lacks attribute 'outputs'", flakeRef);
throw Error("flake '%s' lacks attribute 'outputs'", lockedRef);
for (auto & attr : *vInfo.attrs) {
if (attr.name != sEdition &&
@ -233,7 +283,7 @@ static Flake getFlake(EvalState & state, const FlakeRef & originalRef,
attr.name != sInputs &&
attr.name != sOutputs)
throw Error("flake '%s' has an unsupported attribute '%s', at %s",
flakeRef, attr.name, *attr.pos);
lockedRef, attr.name, *attr.pos);
}
return flake;
@ -242,31 +292,7 @@ static Flake getFlake(EvalState & state, const FlakeRef & originalRef,
Flake getFlake(EvalState & state, const FlakeRef & originalRef, bool allowLookup)
{
FlakeCache flakeCache;
return getFlake(state, originalRef, allowLookup, flakeCache);
}
static std::pair<fetchers::Tree, FlakeRef> getNonFlake(
EvalState & state,
const FlakeRef & originalRef,
bool allowLookup,
FlakeCache & flakeCache)
{
auto flakeRef = lookupInFlakeCache(flakeCache,
maybeLookupFlake(state,
lookupInFlakeCache(flakeCache, originalRef), allowLookup));
auto [sourceInfo, lockedRef] = flakeRef.fetchTree(state.store);
debug("got non-flake source '%s' from '%s'",
state.store->printStorePath(sourceInfo.storePath), lockedRef);
flakeCache.push_back({originalRef, lockedRef});
flakeCache.push_back({flakeRef, lockedRef});
if (state.allowedPaths)
state.allowedPaths->insert(sourceInfo.actualPath);
return std::make_pair(std::move(sourceInfo), lockedRef);
return getFlake(state, originalRef, {}, allowLookup, flakeCache);
}
static void flattenLockFile(
@ -326,7 +352,7 @@ LockedFlake lockFlake(
FlakeCache flakeCache;
auto flake = getFlake(state, topRef, lockFlags.useRegistries, flakeCache);
auto flake = getFlake(state, topRef, {}, lockFlags.useRegistries, flakeCache);
LockFile oldLockFile;
@ -439,7 +465,8 @@ LockedFlake lockFlake(
&& std::equal(inputPath.begin(), inputPath.end(), lb->begin());
if (hasChildUpdate) {
auto inputFlake = getFlake(state, oldLock->second.lockedRef, false, flakeCache);
auto inputFlake = getFlake(
state, oldLock->second.lockedRef, oldLock->second.info, false, flakeCache);
updateLocks(inputFlake.inputs,
(const LockedInputs &) oldLock->second,
@ -470,8 +497,7 @@ LockedFlake lockFlake(
throw Error("cannot update flake input '%s' in pure mode", inputPathS);
if (input.isFlake) {
auto inputFlake = getFlake(state, input.ref,
lockFlags.useRegistries, flakeCache);
auto inputFlake = getFlake(state, input.ref, {}, lockFlags.useRegistries, flakeCache);
newLocks.inputs.insert_or_assign(id,
LockedInput(inputFlake.lockedRef, inputFlake.originalRef, inputFlake.sourceInfo->info));
@ -490,8 +516,8 @@ LockedFlake lockFlake(
}
else {
auto [sourceInfo, lockedRef] = getNonFlake(state, input.ref,
lockFlags.useRegistries, flakeCache);
auto [sourceInfo, lockedRef] = fetchOrSubstituteTree(
state, input.ref, {}, lockFlags.useRegistries, flakeCache);
newLocks.inputs.insert_or_assign(id,
LockedInput(lockedRef, input.ref, sourceInfo.info));
}
@ -602,7 +628,8 @@ static void prim_callFlake(EvalState & state, const Pos & pos, Value * * args, V
auto lazyInput = (LazyInput *) args[0]->attrs;
if (lazyInput->isFlake) {
auto flake = getFlake(state, lazyInput->lockedInput.lockedRef, false);
FlakeCache flakeCache;
auto flake = getFlake(state, lazyInput->lockedInput.lockedRef, lazyInput->lockedInput.info, false, flakeCache);
if (flake.sourceInfo->info.narHash != lazyInput->lockedInput.info.narHash)
throw Error("the content hash of flake '%s' (%s) doesn't match the hash recorded in the referring lock file (%s)",
@ -618,7 +645,8 @@ static void prim_callFlake(EvalState & state, const Pos & pos, Value * * args, V
callFlake(state, flake, lazyInput->lockedInput, v);
} else {
FlakeCache flakeCache;
auto [sourceInfo, lockedRef] = getNonFlake(state, lazyInput->lockedInput.lockedRef, false, flakeCache);
auto [sourceInfo, lockedRef] = fetchOrSubstituteTree(
state, lazyInput->lockedInput.lockedRef, {}, false, flakeCache);
if (sourceInfo.info.narHash != lazyInput->lockedInput.info.narHash)
throw Error("the content hash of repository '%s' (%s) doesn't match the hash recorded in the referring lock file (%s)",

1
tests/flakes.sh
View file

@ -235,6 +235,7 @@ mv $registry.tmp $registry
# Test whether flakes are registered as GC roots for offline use.
# FIXME: use tarballs rather than git.
rm -rf $TEST_HOME/.cache
nix-store --gc # get rid of copies in the store to ensure they get fetched to our git cache
_NIX_FORCE_HTTP=1 nix build -o $TEST_ROOT/result git+file://$flake2Dir#bar
mv $flake1Dir $flake1Dir.tmp
mv $flake2Dir $flake2Dir.tmp