lix/src/build-remote/build-remote.cc
Eelco Dolstra d7653dfc6d
Remove $NIX_BUILD_HOOK and $NIX_CURRENT_LOAD
This is to simplify remote build configuration. These environment
variables predate nix.conf.

The build hook now has a sensible default (namely build-remote).

The current load is kept in the Nix state directory now.
2017-05-01 17:30:16 +02:00

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#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <set>
#include <memory>
#include <tuple>
#include <iomanip>
#if __APPLE__
#include <sys/time.h>
#endif
#include "shared.hh"
#include "pathlocks.hh"
#include "globals.hh"
#include "serialise.hh"
#include "store-api.hh"
#include "derivations.hh"
using namespace nix;
using std::cin;
static void handleAlarm(int sig) {
}
class Machine {
const std::set<string> supportedFeatures;
const std::set<string> mandatoryFeatures;
public:
const string hostName;
const std::vector<string> systemTypes;
const string sshKey;
const unsigned int maxJobs;
const unsigned int speedFactor;
bool enabled;
bool allSupported(const std::set<string> & features) const {
return std::all_of(features.begin(), features.end(),
[&](const string & feature) {
return supportedFeatures.count(feature) ||
mandatoryFeatures.count(feature);
});
}
bool mandatoryMet(const std::set<string> & features) const {
return std::all_of(mandatoryFeatures.begin(), mandatoryFeatures.end(),
[&](const string & feature) {
return features.count(feature);
});
}
Machine(decltype(hostName) hostName,
decltype(systemTypes) systemTypes,
decltype(sshKey) sshKey,
decltype(maxJobs) maxJobs,
decltype(speedFactor) speedFactor,
decltype(supportedFeatures) supportedFeatures,
decltype(mandatoryFeatures) mandatoryFeatures) :
supportedFeatures(supportedFeatures),
mandatoryFeatures(mandatoryFeatures),
hostName(hostName),
systemTypes(systemTypes),
sshKey(sshKey),
maxJobs(maxJobs),
speedFactor(std::max(1U, speedFactor)),
enabled(true)
{};
};;
static std::vector<Machine> readConf()
{
auto conf = getEnv("NIX_REMOTE_SYSTEMS", SYSCONFDIR "/nix/machines");
auto machines = std::vector<Machine>{};
auto lines = std::vector<string>{};
try {
lines = tokenizeString<std::vector<string>>(readFile(conf), "\n");
} catch (const SysError & e) {
if (e.errNo != ENOENT)
throw;
}
for (auto line : lines) {
chomp(line);
line.erase(std::find(line.begin(), line.end(), '#'), line.end());
if (line.empty()) {
continue;
}
auto tokens = tokenizeString<std::vector<string>>(line);
auto sz = tokens.size();
if (sz < 4)
throw FormatError("bad machines.conf file %1%", conf);
machines.emplace_back(tokens[0],
tokenizeString<std::vector<string>>(tokens[1], ","),
tokens[2],
stoull(tokens[3]),
sz >= 5 ? stoull(tokens[4]) : 1LL,
sz >= 6 ?
tokenizeString<std::set<string>>(tokens[5], ",") :
std::set<string>{},
sz >= 7 ?
tokenizeString<std::set<string>>(tokens[6], ",") :
std::set<string>{});
}
return machines;
}
static string currentLoad;
static AutoCloseFD openSlotLock(const Machine & m, unsigned long long slot)
{
std::ostringstream fn_stream(currentLoad, std::ios_base::ate | std::ios_base::out);
fn_stream << "/";
for (auto t : m.systemTypes) {
fn_stream << t << "-";
}
fn_stream << m.hostName << "-" << slot;
return openLockFile(fn_stream.str(), true);
}
static char display_env[] = "DISPLAY=";
static char ssh_env[] = "SSH_ASKPASS=";
int main (int argc, char * * argv)
{
return handleExceptions(argv[0], [&]() {
initNix();
/* Ensure we don't get any SSH passphrase or host key popups. */
if (putenv(display_env) == -1 ||
putenv(ssh_env) == -1)
throw SysError("setting SSH env vars");
if (argc != 5)
throw UsageError("called without required arguments");
auto store = openStore();
auto localSystem = argv[1];
settings.maxSilentTime = std::stoll(argv[2]);
settings.buildTimeout = std::stoll(argv[3]);
verbosity = (Verbosity) std::stoll(argv[4]);
/* It would be more appropriate to use $XDG_RUNTIME_DIR, since
that gets cleared on reboot, but it wouldn't work on OS X. */
currentLoad = settings.nixStateDir + "/current-load";
std::shared_ptr<Store> sshStore;
AutoCloseFD bestSlotLock;
auto machines = readConf();
debug("got %d remote builders", machines.size());
string drvPath;
string hostName;
for (string line; getline(cin, line);) {
auto tokens = tokenizeString<std::vector<string>>(line);
auto sz = tokens.size();
if (sz != 3 && sz != 4)
throw Error("invalid build hook line %1%", line);
auto amWilling = tokens[0] == "1";
auto neededSystem = tokens[1];
drvPath = tokens[2];
auto requiredFeatures = sz == 3 ?
std::set<string>{} :
tokenizeString<std::set<string>>(tokens[3], ",");
auto canBuildLocally = amWilling && (neededSystem == localSystem);
/* Error ignored here, will be caught later */
mkdir(currentLoad.c_str(), 0777);
while (true) {
bestSlotLock = -1;
AutoCloseFD lock = openLockFile(currentLoad + "/main-lock", true);
lockFile(lock.get(), ltWrite, true);
bool rightType = false;
Machine * bestMachine = nullptr;
unsigned long long bestLoad = 0;
for (auto & m : machines) {
if (m.enabled && std::find(m.systemTypes.begin(),
m.systemTypes.end(),
neededSystem) != m.systemTypes.end() &&
m.allSupported(requiredFeatures) &&
m.mandatoryMet(requiredFeatures)) {
rightType = true;
AutoCloseFD free;
unsigned long long load = 0;
for (unsigned long long slot = 0; slot < m.maxJobs; ++slot) {
auto slotLock = openSlotLock(m, slot);
if (lockFile(slotLock.get(), ltWrite, false)) {
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;
}
}
}
if (!bestSlotLock) {
if (rightType && !canBuildLocally)
std::cerr << "# postpone\n";
else
std::cerr << "# decline\n";
break;
}
#if __APPLE__
futimes(bestSlotLock.get(), NULL);
#else
futimens(bestSlotLock.get(), NULL);
#endif
lock = -1;
try {
sshStore = openStore("ssh-ng://" + bestMachine->hostName,
{ {"ssh-key", bestMachine->sshKey },
{"max-connections", "1" } });
hostName = bestMachine->hostName;
} catch (std::exception & e) {
printError("unable to open SSH connection to %s: %s; trying other available machines...",
bestMachine->hostName, e.what());
bestMachine->enabled = false;
continue;
}
goto connected;
}
}
connected:
std::cerr << "# accept\n";
string line;
if (!getline(cin, line))
throw Error("hook caller didn't send inputs");
auto inputs = tokenizeString<PathSet>(line);
if (!getline(cin, line))
throw Error("hook caller didn't send outputs");
auto outputs = tokenizeString<PathSet>(line);
AutoCloseFD uploadLock = openLockFile(currentLoad + "/" + hostName + ".upload-lock", true);
auto old = signal(SIGALRM, handleAlarm);
alarm(15 * 60);
if (!lockFile(uploadLock.get(), ltWrite, true))
printError("somebody is hogging the upload lock for %s, continuing...");
alarm(0);
signal(SIGALRM, old);
copyPaths(store, ref<Store>(sshStore), inputs);
uploadLock = -1;
BasicDerivation drv(readDerivation(drvPath));
drv.inputSrcs = inputs;
printError("building %s on %s", drvPath, storeUri);
sshStore->buildDerivation(drvPath, drv);
PathSet missing;
for (auto & path : outputs)
if (!store->isValidPath(path)) missing.insert(path);
if (!missing.empty()) {
setenv("NIX_HELD_LOCKS", concatStringsSep(" ", missing).c_str(), 1); /* FIXME: ugly */
copyPaths(ref<Store>(sshStore), store, missing);
}
return;
});
}