nix-super/src/libexpr/flake/flake.cc
Eelco Dolstra 343239fc8a Allow nix.conf options to be set in flake.nix
This makes it possible to have per-project configuration in flake.nix,
e.g. binary caches and other stuff:

  nixConfig.bash-prompt-suffix = "ngi# ";
  nixConfig.substituters = [ "https://cache.ngi0.nixos.org/" ];
2020-10-26 20:45:39 +01:00

664 lines
25 KiB
C++

#include "flake.hh"
#include "lockfile.hh"
#include "primops.hh"
#include "eval-inline.hh"
#include "store-api.hh"
#include "fetchers.hh"
#include "finally.hh"
namespace nix {
using namespace flake;
namespace flake {
typedef std::pair<fetchers::Tree, FlakeRef> FetchedFlake;
typedef std::vector<std::pair<FlakeRef, FetchedFlake>> FlakeCache;
static std::optional<FetchedFlake> lookupInFlakeCache(
const FlakeCache & flakeCache,
const FlakeRef & flakeRef)
{
// FIXME: inefficient.
for (auto & i : flakeCache) {
if (flakeRef == i.first) {
debug("mapping '%s' to previously seen input '%s' -> '%s",
flakeRef, i.first, i.second.second);
return i.second;
}
}
return std::nullopt;
}
static std::tuple<fetchers::Tree, FlakeRef, FlakeRef> fetchOrSubstituteTree(
EvalState & state,
const FlakeRef & originalRef,
bool allowLookup,
FlakeCache & flakeCache)
{
auto fetched = lookupInFlakeCache(flakeCache, originalRef);
FlakeRef resolvedRef = originalRef;
if (!fetched) {
if (originalRef.input.isDirect()) {
fetched.emplace(originalRef.fetchTree(state.store));
} else {
if (allowLookup) {
resolvedRef = originalRef.resolve(state.store);
auto fetchedResolved = lookupInFlakeCache(flakeCache, originalRef);
if (!fetchedResolved) fetchedResolved.emplace(resolvedRef.fetchTree(state.store));
flakeCache.push_back({resolvedRef, *fetchedResolved});
fetched.emplace(*fetchedResolved);
}
else {
throw Error("'%s' is an indirect flake reference, but registry lookups are not allowed", originalRef);
}
}
flakeCache.push_back({originalRef, *fetched});
}
auto [tree, lockedRef] = *fetched;
debug("got tree '%s' from '%s'",
state.store->printStorePath(tree.storePath), lockedRef);
if (state.allowedPaths)
state.allowedPaths->insert(tree.actualPath);
assert(!originalRef.input.getNarHash() || tree.storePath == originalRef.input.computeStorePath(*state.store));
return {std::move(tree), resolvedRef, lockedRef};
}
static void forceTrivialValue(EvalState & state, Value & value, const Pos & pos)
{
if (value.type == tThunk && value.isTrivial())
state.forceValue(value, pos);
}
static void expectType(EvalState & state, ValueType type,
Value & value, const Pos & pos)
{
forceTrivialValue(state, value, pos);
if (value.type != type)
throw Error("expected %s but got %s at %s",
showType(type), showType(value.type), pos);
}
static std::map<FlakeId, FlakeInput> parseFlakeInputs(
EvalState & state, Value * value, const Pos & pos);
static FlakeInput parseFlakeInput(EvalState & state,
const std::string & inputName, Value * value, const Pos & pos)
{
expectType(state, tAttrs, *value, pos);
FlakeInput input;
auto sInputs = state.symbols.create("inputs");
auto sUrl = state.symbols.create("url");
auto sFlake = state.symbols.create("flake");
auto sFollows = state.symbols.create("follows");
fetchers::Attrs attrs;
std::optional<std::string> url;
for (nix::Attr attr : *(value->attrs)) {
try {
if (attr.name == sUrl) {
expectType(state, tString, *attr.value, *attr.pos);
url = attr.value->string.s;
attrs.emplace("url", *url);
} else if (attr.name == sFlake) {
expectType(state, tBool, *attr.value, *attr.pos);
input.isFlake = attr.value->boolean;
} else if (attr.name == sInputs) {
input.overrides = parseFlakeInputs(state, attr.value, *attr.pos);
} else if (attr.name == sFollows) {
expectType(state, tString, *attr.value, *attr.pos);
input.follows = parseInputPath(attr.value->string.s);
} else {
if (attr.value->type == tString)
attrs.emplace(attr.name, attr.value->string.s);
else
throw TypeError("flake input attribute '%s' is %s while a string is expected",
attr.name, showType(*attr.value));
}
} catch (Error & e) {
e.addTrace(*attr.pos, hintfmt("in flake attribute '%s'", attr.name));
throw;
}
}
if (attrs.count("type"))
try {
input.ref = FlakeRef::fromAttrs(attrs);
} catch (Error & e) {
e.addTrace(pos, hintfmt("in flake input"));
throw;
}
else {
attrs.erase("url");
if (!attrs.empty())
throw Error("unexpected flake input attribute '%s', at %s", attrs.begin()->first, pos);
if (url)
input.ref = parseFlakeRef(*url, {}, true);
}
if (!input.follows && !input.ref)
input.ref = FlakeRef::fromAttrs({{"type", "indirect"}, {"id", inputName}});
return input;
}
static std::map<FlakeId, FlakeInput> parseFlakeInputs(
EvalState & state, Value * value, const Pos & pos)
{
std::map<FlakeId, FlakeInput> inputs;
expectType(state, tAttrs, *value, pos);
for (nix::Attr & inputAttr : *(*value).attrs) {
inputs.emplace(inputAttr.name,
parseFlakeInput(state,
inputAttr.name,
inputAttr.value,
*inputAttr.pos));
}
return inputs;
}
static Flake getFlake(
EvalState & state,
const FlakeRef & originalRef,
bool allowLookup,
FlakeCache & flakeCache)
{
auto [sourceInfo, resolvedRef, lockedRef] = fetchOrSubstituteTree(
state, originalRef, allowLookup, flakeCache);
// Guard against symlink attacks.
auto flakeFile = canonPath(sourceInfo.actualPath + "/" + lockedRef.subdir + "/flake.nix");
if (!isInDir(flakeFile, sourceInfo.actualPath))
throw Error("'flake.nix' file of flake '%s' escapes from '%s'",
lockedRef, state.store->printStorePath(sourceInfo.storePath));
Flake flake {
.originalRef = originalRef,
.resolvedRef = resolvedRef,
.lockedRef = lockedRef,
.sourceInfo = std::make_shared<fetchers::Tree>(std::move(sourceInfo))
};
if (!pathExists(flakeFile))
throw Error("source tree referenced by '%s' does not contain a '%s/flake.nix' file", lockedRef, lockedRef.subdir);
Value vInfo;
state.evalFile(flakeFile, vInfo, true); // FIXME: symlink attack
expectType(state, tAttrs, vInfo, Pos(foFile, state.symbols.create(flakeFile), 0, 0));
if (auto description = vInfo.attrs->get(state.sDescription)) {
expectType(state, tString, *description->value, *description->pos);
flake.description = description->value->string.s;
}
auto sInputs = state.symbols.create("inputs");
if (auto inputs = vInfo.attrs->get(sInputs))
flake.inputs = parseFlakeInputs(state, inputs->value, *inputs->pos);
auto sOutputs = state.symbols.create("outputs");
if (auto outputs = vInfo.attrs->get(sOutputs)) {
expectType(state, tLambda, *outputs->value, *outputs->pos);
if (outputs->value->lambda.fun->matchAttrs) {
for (auto & formal : outputs->value->lambda.fun->formals->formals) {
if (formal.name != state.sSelf)
flake.inputs.emplace(formal.name, FlakeInput {
.ref = parseFlakeRef(formal.name)
});
}
}
} else
throw Error("flake '%s' lacks attribute 'outputs'", lockedRef);
auto sNixConfig = state.symbols.create("nixConfig");
if (auto nixConfig = vInfo.attrs->get(sNixConfig)) {
expectType(state, tAttrs, *nixConfig->value, *nixConfig->pos);
for (auto & option : *nixConfig->value->attrs) {
forceTrivialValue(state, *option.value, *option.pos);
if (option.value->type == tString)
flake.config.options.insert({option.name, state.forceStringNoCtx(*option.value, *option.pos)});
else if (option.value->type == tInt)
flake.config.options.insert({option.name, state.forceInt(*option.value, *option.pos)});
else if (option.value->type == tBool)
flake.config.options.insert({option.name, state.forceBool(*option.value, *option.pos)});
else if (option.value->isList()) {
std::vector<std::string> ss;
for (unsigned int n = 0; n < option.value->listSize(); ++n) {
auto elem = option.value->listElems()[n];
if (elem->type != tString)
throw TypeError("list element in flake configuration option '%s' is %s while a string is expected",
option.name, showType(*option.value));
ss.push_back(state.forceStringNoCtx(*elem, *option.pos));
}
flake.config.options.insert({option.name, ss});
}
else
throw TypeError("flake configuration option '%s' is %s",
option.name, showType(*option.value));
}
}
for (auto & attr : *vInfo.attrs) {
if (attr.name != state.sDescription &&
attr.name != sInputs &&
attr.name != sOutputs &&
attr.name != sNixConfig)
throw Error("flake '%s' has an unsupported attribute '%s', at %s",
lockedRef, attr.name, *attr.pos);
}
return flake;
}
Flake getFlake(EvalState & state, const FlakeRef & originalRef, bool allowLookup)
{
FlakeCache flakeCache;
return getFlake(state, originalRef, allowLookup, flakeCache);
}
/* Compute an in-memory lock file for the specified top-level flake,
and optionally write it to file, if the flake is writable. */
LockedFlake lockFlake(
EvalState & state,
const FlakeRef & topRef,
const LockFlags & lockFlags)
{
settings.requireExperimentalFeature("flakes");
FlakeCache flakeCache;
auto flake = getFlake(state, topRef, lockFlags.useRegistries, flakeCache);
// FIXME: symlink attack
auto oldLockFile = LockFile::read(
flake.sourceInfo->actualPath + "/" + flake.lockedRef.subdir + "/flake.lock");
debug("old lock file: %s", oldLockFile);
// FIXME: check whether all overrides are used.
std::map<InputPath, FlakeInput> overrides;
std::set<InputPath> overridesUsed, updatesUsed;
for (auto & i : lockFlags.inputOverrides)
overrides.insert_or_assign(i.first, FlakeInput { .ref = i.second });
LockFile newLockFile;
std::vector<FlakeRef> parents;
std::function<void(
const FlakeInputs & flakeInputs,
std::shared_ptr<Node> node,
const InputPath & inputPathPrefix,
std::shared_ptr<const Node> oldNode)>
computeLocks;
computeLocks = [&](
const FlakeInputs & flakeInputs,
std::shared_ptr<Node> node,
const InputPath & inputPathPrefix,
std::shared_ptr<const Node> oldNode)
{
debug("computing lock file node '%s'", printInputPath(inputPathPrefix));
/* Get the overrides (i.e. attributes of the form
'inputs.nixops.inputs.nixpkgs.url = ...'). */
// FIXME: check this
for (auto & [id, input] : flake.inputs) {
for (auto & [idOverride, inputOverride] : input.overrides) {
auto inputPath(inputPathPrefix);
inputPath.push_back(id);
inputPath.push_back(idOverride);
overrides.insert_or_assign(inputPath, inputOverride);
}
}
/* Go over the flake inputs, resolve/fetch them if
necessary (i.e. if they're new or the flakeref changed
from what's in the lock file). */
for (auto & [id, input2] : flakeInputs) {
auto inputPath(inputPathPrefix);
inputPath.push_back(id);
auto inputPathS = printInputPath(inputPath);
debug("computing input '%s'", inputPathS);
/* Do we have an override for this input from one of the
ancestors? */
auto i = overrides.find(inputPath);
bool hasOverride = i != overrides.end();
if (hasOverride) overridesUsed.insert(inputPath);
auto & input = hasOverride ? i->second : input2;
/* Resolve 'follows' later (since it may refer to an input
path we haven't processed yet. */
if (input.follows) {
InputPath target;
if (hasOverride || input.absolute)
/* 'follows' from an override is relative to the
root of the graph. */
target = *input.follows;
else {
/* Otherwise, it's relative to the current flake. */
target = inputPathPrefix;
for (auto & i : *input.follows) target.push_back(i);
}
debug("input '%s' follows '%s'", inputPathS, printInputPath(target));
node->inputs.insert_or_assign(id, target);
continue;
}
assert(input.ref);
/* Do we have an entry in the existing lock file? And we
don't have a --update-input flag for this input? */
std::shared_ptr<LockedNode> oldLock;
updatesUsed.insert(inputPath);
if (oldNode && !lockFlags.inputUpdates.count(inputPath))
if (auto oldLock2 = get(oldNode->inputs, id))
if (auto oldLock3 = std::get_if<0>(&*oldLock2))
oldLock = *oldLock3;
if (oldLock
&& oldLock->originalRef == *input.ref
&& !hasOverride)
{
debug("keeping existing input '%s'", inputPathS);
/* Copy the input from the old lock since its flakeref
didn't change and there is no override from a
higher level flake. */
auto childNode = std::make_shared<LockedNode>(
oldLock->lockedRef, oldLock->originalRef, oldLock->isFlake);
node->inputs.insert_or_assign(id, childNode);
/* If we have an --update-input flag for an input
of this input, then we must fetch the flake to
update it. */
auto lb = lockFlags.inputUpdates.lower_bound(inputPath);
auto hasChildUpdate =
lb != lockFlags.inputUpdates.end()
&& lb->size() > inputPath.size()
&& std::equal(inputPath.begin(), inputPath.end(), lb->begin());
if (hasChildUpdate) {
auto inputFlake = getFlake(
state, oldLock->lockedRef, false, flakeCache);
computeLocks(inputFlake.inputs, childNode, inputPath, oldLock);
} else {
/* No need to fetch this flake, we can be
lazy. However there may be new overrides on the
inputs of this flake, so we need to check
those. */
FlakeInputs fakeInputs;
for (auto & i : oldLock->inputs) {
if (auto lockedNode = std::get_if<0>(&i.second)) {
fakeInputs.emplace(i.first, FlakeInput {
.ref = (*lockedNode)->originalRef,
.isFlake = (*lockedNode)->isFlake,
});
} else if (auto follows = std::get_if<1>(&i.second)) {
fakeInputs.emplace(i.first, FlakeInput {
.follows = *follows,
.absolute = true
});
}
}
computeLocks(fakeInputs, childNode, inputPath, oldLock);
}
} else {
/* We need to create a new lock file entry. So fetch
this input. */
debug("creating new input '%s'", inputPathS);
if (!lockFlags.allowMutable && !input.ref->input.isImmutable())
throw Error("cannot update flake input '%s' in pure mode", inputPathS);
if (input.isFlake) {
auto inputFlake = getFlake(state, *input.ref, lockFlags.useRegistries, flakeCache);
/* Note: in case of an --override-input, we use
the *original* ref (input2.ref) for the
"original" field, rather than the
override. This ensures that the override isn't
nuked the next time we update the lock
file. That is, overrides are sticky unless you
use --no-write-lock-file. */
auto childNode = std::make_shared<LockedNode>(
inputFlake.lockedRef, input2.ref ? *input2.ref : *input.ref);
node->inputs.insert_or_assign(id, childNode);
/* Guard against circular flake imports. */
for (auto & parent : parents)
if (parent == *input.ref)
throw Error("found circular import of flake '%s'", parent);
parents.push_back(*input.ref);
Finally cleanup([&]() { parents.pop_back(); });
/* Recursively process the inputs of this
flake. Also, unless we already have this flake
in the top-level lock file, use this flake's
own lock file. */
computeLocks(
inputFlake.inputs, childNode, inputPath,
oldLock
? std::dynamic_pointer_cast<const Node>(oldLock)
: LockFile::read(
inputFlake.sourceInfo->actualPath + "/" + inputFlake.lockedRef.subdir + "/flake.lock").root);
}
else {
auto [sourceInfo, resolvedRef, lockedRef] = fetchOrSubstituteTree(
state, *input.ref, lockFlags.useRegistries, flakeCache);
node->inputs.insert_or_assign(id,
std::make_shared<LockedNode>(lockedRef, *input.ref, false));
}
}
}
};
computeLocks(
flake.inputs, newLockFile.root, {},
lockFlags.recreateLockFile ? nullptr : oldLockFile.root);
for (auto & i : lockFlags.inputOverrides)
if (!overridesUsed.count(i.first))
warn("the flag '--override-input %s %s' does not match any input",
printInputPath(i.first), i.second);
for (auto & i : lockFlags.inputUpdates)
if (!updatesUsed.count(i))
warn("the flag '--update-input %s' does not match any input", printInputPath(i));
/* Check 'follows' inputs. */
newLockFile.check();
debug("new lock file: %s", newLockFile);
/* Check whether we need to / can write the new lock file. */
if (!(newLockFile == oldLockFile)) {
auto diff = LockFile::diff(oldLockFile, newLockFile);
if (lockFlags.writeLockFile) {
if (auto sourcePath = topRef.input.getSourcePath()) {
if (!newLockFile.isImmutable()) {
if (settings.warnDirty)
warn("will not write lock file of flake '%s' because it has a mutable input", topRef);
} else {
if (!lockFlags.updateLockFile)
throw Error("flake '%s' requires lock file changes but they're not allowed due to '--no-update-lock-file'", topRef);
auto relPath = (topRef.subdir == "" ? "" : topRef.subdir + "/") + "flake.lock";
auto path = *sourcePath + "/" + relPath;
bool lockFileExists = pathExists(path);
if (lockFileExists) {
auto s = chomp(diff);
if (s.empty())
warn("updating lock file '%s'", path);
else
warn("updating lock file '%s':\n%s", path, s);
} else
warn("creating lock file '%s'", path);
newLockFile.write(path);
topRef.input.markChangedFile(
(topRef.subdir == "" ? "" : topRef.subdir + "/") + "flake.lock",
lockFlags.commitLockFile
? std::optional<std::string>(fmt("%s: %s\n\nFlake input changes:\n\n%s",
relPath, lockFileExists ? "Update" : "Add", diff))
: std::nullopt);
/* Rewriting the lockfile changed the top-level
repo, so we should re-read it. FIXME: we could
also just clear the 'rev' field... */
auto prevLockedRef = flake.lockedRef;
FlakeCache dummyCache;
flake = getFlake(state, topRef, lockFlags.useRegistries, dummyCache);
if (lockFlags.commitLockFile &&
flake.lockedRef.input.getRev() &&
prevLockedRef.input.getRev() != flake.lockedRef.input.getRev())
warn("committed new revision '%s'", flake.lockedRef.input.getRev()->gitRev());
/* Make sure that we picked up the change,
i.e. the tree should usually be dirty
now. Corner case: we could have reverted from a
dirty to a clean tree! */
if (flake.lockedRef.input == prevLockedRef.input
&& !flake.lockedRef.input.isImmutable())
throw Error("'%s' did not change after I updated its 'flake.lock' file; is 'flake.lock' under version control?", flake.originalRef);
}
} else
throw Error("cannot write modified lock file of flake '%s' (use '--no-write-lock-file' to ignore)", topRef);
} else
warn("not writing modified lock file of flake '%s':\n%s", topRef, chomp(diff));
}
return LockedFlake { .flake = std::move(flake), .lockFile = std::move(newLockFile) };
}
void callFlake(EvalState & state,
const LockedFlake & lockedFlake,
Value & vRes)
{
auto vLocks = state.allocValue();
auto vRootSrc = state.allocValue();
auto vRootSubdir = state.allocValue();
auto vTmp1 = state.allocValue();
auto vTmp2 = state.allocValue();
mkString(*vLocks, lockedFlake.lockFile.to_string());
emitTreeAttrs(state, *lockedFlake.flake.sourceInfo, lockedFlake.flake.lockedRef.input, *vRootSrc);
mkString(*vRootSubdir, lockedFlake.flake.lockedRef.subdir);
static RootValue vCallFlake = nullptr;
if (!vCallFlake) {
vCallFlake = allocRootValue(state.allocValue());
state.eval(state.parseExprFromString(
#include "call-flake.nix.gen.hh"
, "/"), **vCallFlake);
}
state.callFunction(**vCallFlake, *vLocks, *vTmp1, noPos);
state.callFunction(*vTmp1, *vRootSrc, *vTmp2, noPos);
state.callFunction(*vTmp2, *vRootSubdir, vRes, noPos);
}
static void prim_getFlake(EvalState & state, const Pos & pos, Value * * args, Value & v)
{
auto flakeRefS = state.forceStringNoCtx(*args[0], pos);
auto flakeRef = parseFlakeRef(flakeRefS, {}, true);
if (evalSettings.pureEval && !flakeRef.input.isImmutable())
throw Error("cannot call 'getFlake' on mutable flake reference '%s', at %s (use --impure to override)", flakeRefS, pos);
callFlake(state,
lockFlake(state, flakeRef,
LockFlags {
.updateLockFile = false,
.useRegistries = !evalSettings.pureEval,
.allowMutable = !evalSettings.pureEval,
}),
v);
}
static RegisterPrimOp r2("__getFlake", 1, prim_getFlake, "flakes");
}
Fingerprint LockedFlake::getFingerprint() const
{
// FIXME: as an optimization, if the flake contains a lock file
// and we haven't changed it, then it's sufficient to use
// flake.sourceInfo.storePath for the fingerprint.
return hashString(htSHA256,
fmt("%s;%d;%d;%s",
flake.sourceInfo->storePath.to_string(),
flake.lockedRef.input.getRevCount().value_or(0),
flake.lockedRef.input.getLastModified().value_or(0),
lockFile));
}
Flake::~Flake() { }
void ConfigFile::apply()
{
for (auto & [name, value] : options) {
// FIXME: support 'trusted-public-keys' (and other options), but make it TOFU.
if (name != "bash-prompt-suffix" &&
name != "bash-prompt" &&
name != "substituters" &&
name != "extra-substituters")
{
warn("ignoring untrusted flake configuration option '%s'", name);
continue;
}
// FIXME: Move into libutil/config.cc.
if (auto s = std::get_if<std::string>(&value))
globalConfig.set(name, *s);
else if (auto n = std::get_if<int64_t>(&value))
globalConfig.set(name, fmt("%d", n));
else if (auto b = std::get_if<Explicit<bool>>(&value))
globalConfig.set(name, b->t ? "true" : "false");
else if (auto ss = std::get_if<std::vector<std::string>>(&value))
globalConfig.set(name, concatStringsSep(" ", *ss)); // FIXME: evil
else
assert(false);
}
}
}