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#include "lix/libstore/path.hh"
#include "lix/libutil/async.hh"
#include "lix/libutil/c-calls.hh"
#include "lix/libutil/error.hh"
#include "lix/libutil/file-descriptor.hh"
#include "lix/libutil/logging-rpc.hh"
#include "lix/libutil/logging.hh"
#include "lix/libutil/rpc.hh"
#include "lix/libutil/types-rpc.hh" // IWYU pragma: keep
#include "lix/libutil/types.hh"
#include <algorithm>
#include <capnp/rpc-twoparty.h>
#include <cstring>
#include <exception>
#include <kj/async.h>
#include <kj/time.h>
#include <set>
#include <memory>
#include <string>
#include <tuple>
#if __APPLE__
#include <sys/time.h>
#endif
#include "lix/libstore/machines.hh"
#include "lix/libmain/shared.hh"
#include "lix/libstore/pathlocks.hh"
#include "lix/libstore/globals.hh"
#include "lix/libutil/serialise.hh"
#include "lix/libstore/build-result.hh"
#include "lix/libstore/store-api.hh"
#include "lix/libstore/derivations.hh"
#include "lix/libutil/strings.hh"
#include "lix/libstore/local-store.hh"
#include "lix/libstore/types-rpc.hh"
#include "lix/libcmd/legacy.hh"
#include "lix/libutil/experimental-features.hh"
#include "lix/libutil/hash.hh"
#include "build-remote.hh"
#include "lix/libstore/build/hook-instance.capnp.h"
namespace nix {
namespace {
struct Instance final : rpc::build_remote::HookInstance::Server
{
unsigned int maxBuildJobs;
bool initialized = false, used = false;
kj::Promise<void> init(InitContext context) override;
kj::Promise<void> buildImpl(BuildContext context);
kj::Promise<void> build(BuildContext context) override;
};
}
std::string escapeUri(std::string uri)
{
std::replace(uri.begin(), uri.end(), '/', '_');
return uri;
}
static std::string currentLoad;
static std::string makeLockFilename(const std::string & storeUri) {
// We include 48 bytes of escaped URI to give an idea of what the lock
// is on, then 16 bytes of hash to disambiguate.
// This avoids issues with the escaped URI being very long and causing
// path too long errors, while also avoiding any possibility of collision
// caused by simple truncation.
auto hash = hashString(HashType::SHA256, storeUri).to_string(HashFormat::Base32, false);
return escapeUri(storeUri).substr(0, 48) + "-" + hash.substr(0, 16);
}
static AutoCloseFD openSlotLock(const Machine & m, uint64_t slot)
{
return openLockFile(fmt("%s/%s-%d", currentLoad, makeLockFilename(m.storeUri), slot), true);
}
static bool allSupportedLocally(Store & store, const std::set<std::string>& requiredFeatures) {
for (auto & feature : requiredFeatures)
if (!store.config().systemFeatures.get().count(feature)) return false;
return true;
}
static std::tuple<bool, Machine *, AutoCloseFD> selectBestMachine(
Machines & machines,
const std::string & neededSystem,
const std::set<std::string> & requiredFeatures
)
{
bool rightType = false;
Machine * bestMachine = nullptr;
AutoCloseFD bestSlotLock;
uint64_t bestLoad = 0;
for (auto & m : machines) {
debug("considering building on remote machine '%s'", m.storeUri);
if (m.enabled && m.systemSupported(neededSystem) && m.allSupported(requiredFeatures)
&& m.mandatoryMet(requiredFeatures))
{
rightType = true;
AutoCloseFD free;
uint64_t load = 0;
for (uint64_t slot = 0; slot < m.maxJobs; ++slot) {
auto slotLock = openSlotLock(m, slot);
if (tryLockFile(slotLock.get(), ltWrite)) {
if (!free) {
free = std::move(slotLock);
}
} else {
++load;
}
}
if (!free) {
continue;
}
bool best = false;
if (!bestSlotLock) {
best = true;
} else if (load / m.speedFactor < bestLoad / bestMachine->speedFactor) {
best = true;
} else if (load / m.speedFactor == bestLoad / bestMachine->speedFactor) {
if (m.speedFactor > bestMachine->speedFactor) {
best = true;
} else if (m.speedFactor == bestMachine->speedFactor) {
if (load < bestLoad) {
best = true;
}
}
}
if (best) {
bestLoad = load;
bestSlotLock = std::move(free);
bestMachine = &m;
}
}
}
return {rightType, bestMachine, std::move(bestSlotLock)};
}
static void printSelectionFailureMessage(
Verbosity level,
const std::string_view drvstr,
const Machines & machines,
const std::string & neededSystem,
const std::set<std::string> & requiredFeatures
)
{
std::string machinesFormatted;
for (auto & m : machines) {
machinesFormatted += HintFmt(
"\n([%s], %s, [%s], [%s])",
concatStringsSep<StringSet>(", ", m.systemTypes),
m.maxJobs,
concatStringsSep<StringSet>(", ", m.supportedFeatures),
concatStringsSep<StringSet>(", ", m.mandatoryFeatures)
)
.str();
}
printMsg(
level,
"Failed to find a machine for remote build!\n"
"derivation: %s\n"
"required (system, features): (%s, [%s])\n"
"%s available machines:\n"
"(systems, maxjobs, supportedFeatures, mandatoryFeatures)%s",
drvstr,
neededSystem,
concatStringsSep<StringSet>(", ", requiredFeatures),
machines.size(),
Uncolored(machinesFormatted)
);
}
namespace {
struct BuilderConnection
{
AutoCloseFD slotLock;
std::shared_ptr<Store> sshStore;
std::string storeUri;
Pipe logPipe;
// start the thread that reads ssh stderr and turns it into log items.
// this future *must* outlive sshStore, otherwise it will never finish
kj::Promise<Result<void>> startLogThread(std::string buildDescription, std::string drvPath)
try {
if (!logPipe.readSide) {
co_return result::success();
}
logPipe.writeSide.close();
// NOTE this is very similar to handleBuilderOutput in DerivationGoal, but unlike
// the derivation goal we do not need to handle EIO from a pty here. we also have
// no timeouts or limits to keep track of, which makes deduplication less useful.
auto act = logger->startActivity(
lvlInfo, actBuild, buildDescription, Logger::Fields{drvPath, storeUri, 1, 1}
);
std::map<ActivityId, Activity> activities;
auto reader = AIO().lowLevelProvider.wrapInputFd(logPipe.readSide.get());
LogLineSplitter splitter;
auto flushLine = [&](const std::string & line) {
if (const auto state =
handleJSONLogMessage(line, act, activities, "the derivation builder"))
{
return *state;
} else {
return act.result(resBuildLogLine, line);
}
};
auto buf = kj::heapArray<char>(4096);
while (true) {
const auto got = co_await reader->tryRead(buf.begin(), 1, buf.size());
if (got == 0) {
break;
}
std::string_view data{buf.begin(), got};
while (!data.empty()) {
if (auto line = splitter.feed(data)) {
if (flushLine(*line) == Logger::BufferState::NeedsFlush) {
TRY_AWAIT(act.getLogger().flush());
}
}
}
}
if (auto line = splitter.finish(); !line.empty()) {
(void) flushLine(line);
TRY_AWAIT(act.getLogger().flush());
}
co_return result::success();
} catch (...) {
co_return result::current_exception();
}
};
struct AcceptedBuild final : rpc::build_remote::HookInstance::AcceptedBuild::Server
{
ref<Store> store;
StorePath drvPath;
BuilderConnection builder;
bool used = false;
AcceptedBuild(ref<Store> store, StorePath drvPath, BuilderConnection builder)
: store(store)
, drvPath(drvPath)
, builder(std::move(builder))
{
}
kj::Promise<void> runImpl(RunContext context);
kj::Promise<void> run(RunContext context) override;
};
enum class BuildRejected { Temporarily, Permanently };
}
static kj::Promise<Result<std::variant<BuildRejected, BuilderConnection>>> connectToBuilder(
const ref<Store> & store,
const StorePath & drvPath,
Machines & machines,
const unsigned int maxBuildJobs,
const bool amWilling,
const std::string & neededSystem,
const std::set<std::string> & requiredFeatures
)
try {
AutoCloseFD bestSlotLock;
/* It would be possible to build locally after some builds clear out,
so don't show the warning now: */
bool couldBuildLocally = maxBuildJobs > 0
&& (neededSystem == settings.thisSystem
|| settings.extraPlatforms.get().count(neededSystem) > 0)
&& allSupportedLocally(*store, requiredFeatures);
/* It's possible to build this locally right now: */
bool canBuildLocally = amWilling && couldBuildLocally;
/* Error ignored here, will be caught later */
(void) sys::mkdir(currentLoad, 0777);
while (true) {
bestSlotLock.reset();
AutoCloseFD lock = openLockFile(currentLoad + "/main-lock", true);
TRY_AWAIT(lockFileAsync(lock.get(), ltWrite));
auto [rightType, bestMachine, slotLock] =
selectBestMachine(machines, neededSystem, requiredFeatures);
bestSlotLock = std::move(slotLock);
if (!bestSlotLock) {
if (rightType && !canBuildLocally) {
co_return BuildRejected::Temporarily;
} else {
printSelectionFailureMessage(
couldBuildLocally ? lvlChatty : lvlWarn,
drvPath.to_string(),
machines,
neededSystem,
requiredFeatures
);
co_return BuildRejected::Permanently;
}
}
#if __APPLE__
futimes(bestSlotLock.get(), nullptr);
#else
futimens(bestSlotLock.get(), nullptr);
#endif
lock.reset();
std::shared_ptr<Store> sshStore;
Pipe logPipe;
try {
auto act = logger->startActivity(
lvlTalkative, actUnknown, fmt("connecting to '%s'", bestMachine->storeUri)
);
std::tie(sshStore, logPipe) = TRY_AWAIT(bestMachine->openStore());
TRY_AWAIT(sshStore->connect());
co_return BuilderConnection{
std::move(bestSlotLock), sshStore, bestMachine->storeUri, std::move(logPipe)
};
} catch (std::exception & e) { // NOLINT(lix-foreign-exceptions)
std::string msg = logPipe.readSide ? chomp(drainFD(logPipe.readSide.get(), false)) : "";
printError(
"cannot build on '%s': %s%s",
bestMachine->storeUri,
e.what(),
msg.empty() ? "" : ": " + msg
);
bestMachine->enabled = false;
}
}
} catch (...) {
co_return result::current_exception();
}
static int main_build_remote(AsyncIoRoot & aio, std::string programName, Strings argv)
{
{
/* Ensure we don't get any SSH passphrase or host key popups. */
unsetenv("DISPLAY");
unsetenv("SSH_ASKPASS");
/* If we ever use the common args framework, make sure to
remove initPlugins below and initialize settings first.
*/
if (argv.size() != 1)
throw UsageError("called without required arguments");
verbosity = (Verbosity) std::stoll(argv.front());
auto conn = aio.kj.lowLevelProvider->wrapUnixSocketFd(1);
capnp::TwoPartyServer srv(kj::heap<Instance>());
srv.accept(*conn, 1).wait(aio.kj.waitScope);
return 0;
}
}
kj::Promise<void> Instance::init(InitContext context)
{
try {
if (initialized) {
throw Error("build hook can only be initialized once");
}
logger = rpc::log::makeRpcLoggerClient(context.getParams().getLogger());
/* Read the parent's settings. */
for (const auto & [name, value] : rpc::to<StringMap>(context.getParams().getSettings())) {
settings.set(name, value);
}
maxBuildJobs = settings.maxBuildJobs;
settings.maxBuildJobs.set("1"); // hack to make tests with local?root= work
initPlugins();
initialized = true;
context.getResults().initResult().setGood();
} catch (...) {
RPC_FILL(context.getResults(), initResult, std::current_exception());
}
return kj::READY_NOW;
}
kj::Promise<void> Instance::buildImpl(BuildContext context)
try {
if (!initialized) {
throw Error("build hook not fully initialized");
}
// FIXME this does not open a daemon connection for historical reasons.
// we may create a lot of build hook instances, and having each of them
// also create a daemon instance is inefficient and wasteful. in future
// versions of the build hook (where we don't need one hook process per
// build) we should change this to using a daemon connection, ideally a
// daemon connection provided by the parent via file descriptor passing
auto store = TRY_AWAIT(openStore(settings.storeUri, {}, AllowDaemon::Disallow));
/* It would be more appropriate to use $XDG_RUNTIME_DIR, since
that gets cleared on reboot, but it wouldn't work on macOS. */
auto currentLoadName = "/current-load";
if (auto localStore = store.try_cast_shared<LocalFSStore>()) {
currentLoad = std::string{localStore->config().stateDir} + currentLoadName;
} else {
currentLoad = settings.nixStateDir + currentLoadName;
}
auto machines = getMachines();
debug("got %d remote builders", machines.size());
if (machines.empty()) {
context.getResults().initResult().initGood().setDeclinePermanently();
co_return;
}
auto amWilling = context.getParams().getAmWilling();
auto neededSystem = rpc::to<std::string>(context.getParams().getNeededSystem());
auto drvPath = from(context.getParams().getDrvPath(), *store);
auto requiredFeatures =
rpc::to<std::set<std::string>>(context.getParams().getRequiredFeatures());
auto result = TRY_AWAIT(connectToBuilder(
store, drvPath, machines, maxBuildJobs, amWilling, neededSystem, requiredFeatures
));
if (auto immediateResponse = std::get_if<BuildRejected>(&result)) {
switch (*immediateResponse) {
case BuildRejected::Temporarily:
context.getResults().initResult().initGood().setPostpone();
co_return;
case BuildRejected::Permanently:
context.getResults().initResult().initGood().setDecline();
co_return;
}
}
auto builder = std::get_if<BuilderConnection>(&result);
assert(builder);
auto ac = context.getResults().initResult().initGood().initAccept();
ac.setMachine(kj::heap<AcceptedBuild>(store, drvPath, std::move(*builder)));
} catch (...) {
RPC_FILL(context.getResults(), initResult, std::current_exception());
}
kj::Promise<void> Instance::build(BuildContext context)
try {
if (used) {
throw Error("build hooks can only accept a single job");
}
used = true; // lock out other rpc calls during processing
co_await buildImpl(context);
TRY_AWAIT(logger->flush());
used = context.getResults().getResult().getGood().isAccept();
} catch (...) {
RPC_FILL(context.getResults(), getResult, std::current_exception());
}
kj::Promise<void> AcceptedBuild::run(RunContext context)
{
try {
auto oldLogger = logger;
logger = rpc::log::makeRpcLoggerClient(context.getParams().getLogger());
TRY_AWAIT(oldLogger->flush());
KJ_DEFER({
delete logger;
logger = oldLogger;
});
if (used) {
throw Error("build hooks builds are single-use items");
}
used = true;
co_await runImpl(context);
TRY_AWAIT(logger->flush());
} catch (...) {
RPC_FILL(context.getResults(), getResult, std::current_exception());
}
}
kj::Promise<void> AcceptedBuild::runImpl(RunContext context)
{
try {
auto logHandler = builder.startLogThread(
fmt("%s on '%s'",
rpc::to<std::string_view>(context.getParams().getDescription()),
builder.storeUri),
store->printStorePath(drvPath)
);
auto & sshStore = builder.sshStore;
auto & storeUri = builder.storeUri;
auto inputs = rpc::to<std::set<StorePath>>(context.getParams().getInputs(), *store);
auto wantedOutputs = rpc::to<std::set<std::string>>(context.getParams().getWantedOutputs());
auto lockFileName = currentLoad + "/" + makeLockFilename(storeUri) + ".upload-lock";
AutoCloseFD uploadLock = openLockFile(lockFileName, true);
{
auto act = logger->startActivity(
lvlTalkative, actUnknown, fmt("waiting for the upload lock to '%s'", storeUri)
);
auto result = TRY_AWAIT(
AIO().timeoutAfter(15 * kj::MINUTES, lockFileAsync(uploadLock.get(), ltWrite))
);
if (!result) {
printError("somebody is hogging the upload lock for '%s', continuing...", storeUri);
}
}
auto substitute = settings.buildersUseSubstitutes ? Substitute : NoSubstitute;
{
auto act = logger->startActivity(
lvlTalkative, actUnknown, fmt("copying dependencies to '%s'", storeUri)
);
TRY_AWAIT(copyPaths(*store, *sshStore, inputs, NoRepair, NoCheckSigs, substitute));
}
uploadLock.reset();
auto drv = TRY_AWAIT(store->readDerivation(drvPath));
std::optional<BuildResult> optResult;
// If we don't know whether we are trusted (e.g. `ssh://`
// stores), we assume we are. This is necessary for backwards
// compat.
bool trustedOrLegacy = ({
std::optional trusted = TRY_AWAIT(sshStore->isTrustedClient());
!trusted || *trusted;
});
// See the very large comment in `case WorkerProto::Op::BuildDerivation:` in
// `lix/libstore/daemon.cc` that explains the trust model here.
//
// This condition mirrors that: that code enforces the "rules" outlined there;
// we do the best we can given those "rules".
if (trustedOrLegacy || drv.type().isCA()) {
// Hijack the inputs paths of the derivation to include all
// the paths that come from the `inputDrvs` set. We don’t do
// that for the derivations whose `inputDrvs` is empty
// because:
//
// 1. It’s not needed
//
// 2. Changing the `inputSrcs` set changes the associated
// output ids, which break CA derivations
if (!drv.inputDrvs.empty()) {
drv.inputSrcs = inputs;
}
optResult =
TRY_AWAIT(sshStore->buildDerivation(drvPath, (const BasicDerivation &) drv));
} else {
TRY_AWAIT(copyClosure(
*store, *sshStore, StorePathSet{drvPath}, NoRepair, NoCheckSigs, substitute
));
auto res = TRY_AWAIT(sshStore->buildPathsWithResults({DerivedPath::Built{
.drvPath = makeConstantStorePath(drvPath),
.outputs = OutputsSpec::All{},
}}));
// One path to build should produce exactly one build result
assert(res.size() == 1);
optResult = std::move(res[0]);
}
auto & result = *optResult;
if (!result.success()) {
throw Error(
"build of '%s' on '%s' failed: %s",
store->printStorePath(drvPath),
storeUri,
result.errorMsg
);
}
StorePathSet missingPaths;
auto outputPaths = drv.outputsAndPaths(*store);
for (auto & [outputName, outputPath] : outputPaths) {
if (!TRY_AWAIT(store->isValidPath(outputPath.second))) {
missingPaths.insert(outputPath.second);
}
}
if (!missingPaths.empty()) {
auto act = logger->startActivity(
lvlTalkative, actUnknown, fmt("copying outputs from '%s'", storeUri)
);
if (auto localStore = store.try_cast_shared<LocalStore>())
for (auto & path : missingPaths)
localStore->locksHeld.insert(store->printStorePath(path)); /* FIXME: ugly */
TRY_AWAIT(
copyPaths(*sshStore, *store, missingPaths, NoRepair, NoCheckSigs, NoSubstitute)
);
}
// drop store connection, let log handler process any remaining input
builder.sshStore = nullptr;
TRY_AWAIT(logHandler);
context.getResults().initResult().setGood();
} catch (...) {
RPC_FILL(context.getResults(), initResult, std::current_exception());
}
}
void registerLegacyBuildRemote() {
LegacyCommandRegistry::add("build-remote", main_build_remote);
}
}
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