treewide: start removing tests related to constituents

The feature cannot easily be ported to nix-eval-jobs since it requires
deep integration into the evaluator, and h.n.o doesn't use it. Later
more of this will be ripped out.

.gitignore

@@ -20,7 +20,6 @@ Makefile.in
 /src/sql/hydra-postgresql.sql
 /src/sql/hydra-sqlite.sql
 /src/sql/tmp.sqlite
-/src/hydra-eval-jobs/hydra-eval-jobs
 /src/root/static/bootstrap
 /src/root/static/js/flot
 /tests

configure.ac

@@ -61,7 +61,6 @@ AC_CONFIG_FILES([
   doc/manual/Makefile
   src/Makefile
   src/hydra-evaluator/Makefile
-  src/hydra-eval-jobs/Makefile
   src/hydra-queue-runner/Makefile
   src/sql/Makefile
   src/ttf/Makefile

flake.nix

@@ -10,7 +10,7 @@
   inputs.nix-eval-jobs.inputs.nixpkgs.follows = "nixpkgs";
   inputs.nix-eval-jobs.inputs.lix.follows = "lix";
 
-  outputs = { self, nixpkgs, lix }:
+  outputs = { self, nix-eval-jobs, nixpkgs, lix }:
     let
       systems = [ "x86_64-linux" "aarch64-linux" ];
       forEachSystem = nixpkgs.lib.genAttrs systems;
@@ -29,6 +29,7 @@
       overlays.default = final: prev: {
         hydra = final.callPackage ./package.nix {
           inherit (final.lib) fileset;
+          nix-eval-jobs = nix-eval-jobs.packages.${final.system}.default;
           rawSrc = self;
         };
       };

package.nix

@@ -48,6 +48,7 @@
 , xz
 , gnutar
 , gnused
+, nix-eval-jobs
 
 , rpm
 , dpkg
@@ -192,6 +193,7 @@ stdenv.mkDerivation (finalAttrs: {
     openldap
     postgresql_13
     pixz
+    nix-eval-jobs
   ];
 
   checkInputs = [
@@ -220,6 +222,7 @@ stdenv.mkDerivation (finalAttrs: {
       darcs
       gnused
       breezy
+      nix-eval-jobs
     ] ++ lib.optionals stdenv.isLinux [ rpm dpkg cdrkit ]
   );
 
@@ -228,7 +231,7 @@ stdenv.mkDerivation (finalAttrs: {
   shellHook = ''
     pushd $(git rev-parse --show-toplevel) >/dev/null
 
-    PATH=$(pwd)/src/hydra-evaluator:$(pwd)/src/script:$(pwd)/src/hydra-eval-jobs:$(pwd)/src/hydra-queue-runner:$PATH
+    PATH=$(pwd)/src/hydra-evaluator:$(pwd)/src/script:$(pwd)/src/hydra-queue-runner:$PATH
     PERL5LIB=$(pwd)/src/lib:$PERL5LIB
     export HYDRA_HOME="$(pwd)/src/"
     mkdir -p .hydra-data

src/Makefile.am

@@ -1,3 +1,3 @@
-SUBDIRS = hydra-evaluator hydra-eval-jobs hydra-queue-runner sql script lib root ttf
+SUBDIRS = hydra-evaluator hydra-queue-runner sql script lib root ttf
 BOOTCLEAN_SUBDIRS = $(SUBDIRS)
 DIST_SUBDIRS      = $(SUBDIRS)

src/hydra-eval-jobs/Makefile.am

@@ -1,5 +0,0 @@
-bin_PROGRAMS = hydra-eval-jobs
-
-hydra_eval_jobs_SOURCES = hydra-eval-jobs.cc
-hydra_eval_jobs_LDADD = $(NIX_LIBS) -llixcmd
-hydra_eval_jobs_CXXFLAGS = $(NIX_CFLAGS) -I ../libhydra

src/hydra-eval-jobs/hydra-eval-jobs.cc

@@ -1,577 +0,0 @@
-#include <iostream>
-#include <thread>
-#include <optional>
-#include <unordered_map>
-
-#include "shared.hh"
-#include "store-api.hh"
-#include "eval.hh"
-#include "eval-inline.hh"
-#include "eval-settings.hh"
-#include "signals.hh"
-#include "terminal.hh"
-#include "get-drvs.hh"
-#include "globals.hh"
-#include "lix/libcmd/common-eval-args.hh"
-#include "flake/flakeref.hh"
-#include "flake/flake.hh"
-#include "attr-path.hh"
-#include "derivations.hh"
-#include "local-fs-store.hh"
-
-#include "hydra-config.hh"
-
-#include <sys/types.h>
-#include <sys/wait.h>
-#include <sys/resource.h>
-
-#include <nlohmann/json.hpp>
-
-void check_pid_status_nonblocking(pid_t check_pid)
-{
-    // Only check 'initialized' and known PID's
-    if (check_pid <= 0) { return; }
-
-    int wstatus = 0;
-    pid_t pid = waitpid(check_pid, &wstatus, WNOHANG);
-    // -1 = failure, WNOHANG: 0 = no change
-    if (pid <= 0) { return; }
-
-    std::cerr << "child process (" << pid << ") ";
-
-    if (WIFEXITED(wstatus)) {
-        std::cerr << "exited with status=" << WEXITSTATUS(wstatus) << std::endl;
-    } else if (WIFSIGNALED(wstatus)) {
-        std::cerr << "killed by signal=" << WTERMSIG(wstatus) << std::endl;
-    } else if (WIFSTOPPED(wstatus)) {
-        std::cerr << "stopped by signal=" << WSTOPSIG(wstatus) << std::endl;
-    } else if (WIFCONTINUED(wstatus)) {
-        std::cerr << "continued" << std::endl;
-    }
-}
-
-using namespace nix;
-
-static Path gcRootsDir;
-static size_t maxMemorySize;
-
-struct MyArgs : MixEvalArgs, MixCommonArgs, RootArgs
-{
-    Path releaseExpr;
-    bool flake = false;
-    bool dryRun = false;
-
-    MyArgs() : MixCommonArgs("hydra-eval-jobs")
-    {
-        addFlag({
-            .longName = "gc-roots-dir",
-            .description = "garbage collector roots directory",
-            .labels = {"path"},
-            .handler = {&gcRootsDir}
-        });
-
-        addFlag({
-            .longName = "dry-run",
-            .description = "don't create store derivations",
-            .handler = {&dryRun, true}
-        });
-
-        addFlag({
-            .longName = "flake",
-            .description = "build a flake",
-            .handler = {&flake, true}
-        });
-
-        expectArg("expr", &releaseExpr);
-    }
-};
-
-static MyArgs myArgs;
-
-static std::string queryMetaStrings(EvalState & state, DrvInfo & drv, const std::string & name, const std::string & subAttribute)
-{
-    Strings res;
-    std::function<void(Value & v)> rec;
-
-    rec = [&](Value & v) {
-        state.forceValue(v, noPos);
-        if (v.type() == nString)
-            res.push_back(v.string.s);
-        else if (v.isList())
-            for (unsigned int n = 0; n < v.listSize(); ++n)
-                rec(*v.listElems()[n]);
-        else if (v.type() == nAttrs) {
-            auto a = v.attrs->find(state.symbols.create(subAttribute));
-            if (a != v.attrs->end())
-                res.push_back(std::string(state.forceString(*a->value, a->pos, "while evaluating meta attributes")));
-        }
-    };
-
-    Value * v = drv.queryMeta(name);
-    if (v) rec(*v);
-
-    return concatStringsSep(", ", res);
-}
-
-static void worker(
-    EvalState & state,
-    Bindings & autoArgs,
-    AutoCloseFD & to,
-    AutoCloseFD & from)
-{
-    Value vTop;
-
-    if (myArgs.flake) {
-        using namespace flake;
-
-        auto flakeRef = parseFlakeRef(myArgs.releaseExpr);
-
-        auto vFlake = state.allocValue();
-
-        auto lockedFlake = lockFlake(state, flakeRef,
-            LockFlags {
-                .updateLockFile = false,
-                .useRegistries = false,
-                .allowUnlocked = false,
-            });
-
-        callFlake(state, lockedFlake, *vFlake);
-
-        auto vOutputs = vFlake->attrs->get(state.symbols.create("outputs"))->value;
-        state.forceValue(*vOutputs, noPos);
-
-        auto aHydraJobs = vOutputs->attrs->get(state.symbols.create("hydraJobs"));
-        if (!aHydraJobs)
-            aHydraJobs = vOutputs->attrs->get(state.symbols.create("checks"));
-        if (!aHydraJobs)
-            throw Error("flake '%s' does not provide any Hydra jobs or checks", flakeRef);
-
-        vTop = *aHydraJobs->value;
-
-    } else {
-        state.evalFile(lookupFileArg(state, myArgs.releaseExpr), vTop);
-    }
-
-    auto vRoot = state.allocValue();
-    state.autoCallFunction(autoArgs, vTop, *vRoot);
-
-    while (true) {
-        /* Wait for the master to send us a job name. */
-        writeLine(to.get(), "next");
-
-        auto s = readLine(from.get());
-        if (s == "exit") break;
-        if (!s.starts_with("do ")) abort();
-        std::string attrPath(s, 3);
-
-        debug("worker process %d at '%s'", getpid(), attrPath);
-
-        /* Evaluate it and send info back to the master. */
-        nlohmann::json reply;
-
-        try {
-            auto vTmp = findAlongAttrPath(state, attrPath, autoArgs, *vRoot).first;
-
-            auto v = state.allocValue();
-            state.autoCallFunction(autoArgs, *vTmp, *v);
-
-            if (auto drv = getDerivation(state, *v, false)) {
-
-                // CA derivations do not have static output paths, so we
-                // have to defensively not query output paths in case we
-                // encounter one.
-                DrvInfo::Outputs outputs = drv->queryOutputs(
-                    !experimentalFeatureSettings.isEnabled(Xp::CaDerivations));
-
-                if (drv->querySystem() == "unknown")
-                    state.error<EvalError>("derivation must have a 'system' attribute").debugThrow();
-
-                auto drvPath = state.store->printStorePath(drv->requireDrvPath());
-
-                nlohmann::json job;
-
-                job["nixName"] = drv->queryName();
-                job["system"] =drv->querySystem();
-                job["drvPath"] = drvPath;
-                job["description"] = drv->queryMetaString("description");
-                job["license"] = queryMetaStrings(state, *drv, "license", "shortName");
-                job["homepage"] = drv->queryMetaString("homepage");
-                job["maintainers"] = queryMetaStrings(state, *drv, "maintainers", "email");
-                job["schedulingPriority"] = drv->queryMetaInt("schedulingPriority", 100);
-                job["timeout"] = drv->queryMetaInt("timeout", 36000);
-                job["maxSilent"] = drv->queryMetaInt("maxSilent", 7200);
-                job["isChannel"] = drv->queryMetaBool("isHydraChannel", false);
-
-                /* If this is an aggregate, then get its constituents. */
-                auto a = v->attrs->get(state.symbols.create("_hydraAggregate"));
-                if (a && state.forceBool(*a->value, a->pos, "while evaluating the `_hydraAggregate` attribute")) {
-                    auto a = v->attrs->get(state.symbols.create("constituents"));
-                    if (!a)
-                        state.error<EvalError>("derivation must have a ‘constituents’ attribute").debugThrow();
-
-                    NixStringContext context;
-                    state.coerceToString(a->pos, *a->value, context, "while evaluating the `constituents` attribute", true, false);
-                    for (auto & c : context)
-                        std::visit(overloaded {
-                            [&](const NixStringContextElem::Built & b) {
-                                job["constituents"].push_back(b.drvPath->to_string(*state.store));
-                            },
-                            [&](const NixStringContextElem::Opaque & o) {
-                            },
-                            [&](const NixStringContextElem::DrvDeep & d) {
-                            },
-                        }, c.raw);
-
-                    state.forceList(*a->value, a->pos, "while evaluating the `constituents` attribute");
-                    for (unsigned int n = 0; n < a->value->listSize(); ++n) {
-                        auto v = a->value->listElems()[n];
-                        state.forceValue(*v, noPos);
-                        if (v->type() == nString)
-                            job["namedConstituents"].push_back(v->str());
-                    }
-                }
-
-                /* Register the derivation as a GC root.  !!! This
-                   registers roots for jobs that we may have already
-                   done. */
-                auto localStore = state.store.dynamic_pointer_cast<LocalFSStore>();
-                if (gcRootsDir != "" && localStore) {
-                    Path root = gcRootsDir + "/" + std::string(baseNameOf(drvPath));
-                    if (!pathExists(root))
-                        localStore->addPermRoot(localStore->parseStorePath(drvPath), root);
-                }
-
-                nlohmann::json out;
-                for (auto & [outputName, optOutputPath] : outputs) {
-                    if (optOutputPath) {
-                        out[outputName] = state.store->printStorePath(*optOutputPath);
-                    } else {
-                        // See the `queryOutputs` call above; we should
-                        // not encounter missing output paths otherwise.
-                        assert(experimentalFeatureSettings.isEnabled(Xp::CaDerivations));
-                        out[outputName] = nullptr;
-                    }
-                }
-                job["outputs"] = std::move(out);
-                reply["job"] = std::move(job);
-            }
-
-            else if (v->type() == nAttrs) {
-                auto attrs = nlohmann::json::array();
-                StringSet ss;
-                for (auto & i : v->attrs->lexicographicOrder(state.symbols)) {
-                    std::string name(state.symbols[i->name]);
-                    if (name.find(' ') != std::string::npos) {
-                        printError("skipping job with illegal name '%s'", name);
-                        continue;
-                    }
-                    attrs.push_back(name);
-                }
-                reply["attrs"] = std::move(attrs);
-            }
-
-            else if (v->type() == nNull)
-                ;
-
-            else state.error<TypeError>("attribute '%s' is %s, which is not supported", attrPath, showType(*v)).debugThrow();
-
-        } catch (EvalError & e) {
-            auto msg = e.msg();
-            // Transmits the error we got from the previous evaluation
-            // in the JSON output.
-            reply["error"] = filterANSIEscapes(msg, true);
-            // Don't forget to print it into the STDERR log, this is
-            // what's shown in the Hydra UI.
-            printError(msg);
-        }
-
-        writeLine(to.get(), reply.dump());
-
-        /* If our RSS exceeds the maximum, exit. The master will
-           start a new process. */
-        struct rusage r;
-        getrusage(RUSAGE_SELF, &r);
-        if ((size_t) r.ru_maxrss > maxMemorySize * 1024) break;
-    }
-
-    writeLine(to.get(), "restart");
-}
-
-int main(int argc, char * * argv)
-{
-    /* Prevent undeclared dependencies in the evaluation via
-       $NIX_PATH. */
-    unsetenv("NIX_PATH");
-
-    return handleExceptions(argv[0], [&]() {
-
-        auto config = std::make_unique<HydraConfig>();
-
-        auto nrWorkers = config->getIntOption("evaluator_workers", 1);
-        maxMemorySize = config->getIntOption("evaluator_max_memory_size", 4096);
-
-        initNix();
-        initGC();
-
-        myArgs.parseCmdline(argvToStrings(argc, argv));
-
-        auto pureEval = config->getBoolOption("evaluator_pure_eval", myArgs.flake);
-
-        /* FIXME: The build hook in conjunction with import-from-derivation is causing "unexpected EOF" during eval */
-        settings.builders = "";
-
-        /* Prevent access to paths outside of the Nix search path and
-           to the environment. */
-        evalSettings.restrictEval = true;
-
-        /* When building a flake, use pure evaluation (no access to
-           'getEnv', 'currentSystem' etc. */
-        evalSettings.pureEval = pureEval;
-
-        if (myArgs.dryRun) settings.readOnlyMode = true;
-
-        if (myArgs.releaseExpr == "") throw UsageError("no expression specified");
-
-        if (gcRootsDir == "") printMsg(lvlError, "warning: `--gc-roots-dir' not specified");
-
-        struct State
-        {
-            std::set<std::string> todo{""};
-            std::set<std::string> active;
-            nlohmann::json jobs;
-            std::exception_ptr exc;
-        };
-
-        std::condition_variable wakeup;
-
-        Sync<State> state_;
-
-        /* Start a handler thread per worker process. */
-        auto handler = [&]()
-        {
-            Pid pid;
-            try {
-                AutoCloseFD from, to;
-
-                while (true) {
-
-                    /* Start a new worker process if necessary. */
-                    if (!pid) {
-                        Pipe toPipe, fromPipe;
-                        toPipe.create();
-                        fromPipe.create();
-                        pid = startProcess(
-                            [&,
-                             to{std::make_shared<AutoCloseFD>(std::move(fromPipe.writeSide))},
-                             from{std::make_shared<AutoCloseFD>(std::move(toPipe.readSide))}
-                            ]()
-                            {
-                                try {
-                                    EvalState state(myArgs.searchPath, openStore());
-                                    Bindings & autoArgs = *myArgs.getAutoArgs(state);
-                                    worker(state, autoArgs, *to, *from);
-                                } catch (Error & e) {
-                                    nlohmann::json err;
-                                    auto msg = e.msg();
-                                    err["error"] = filterANSIEscapes(msg, true);
-                                    printError(msg);
-                                    writeLine(to->get(), err.dump());
-                                    // Don't forget to print it into the STDERR log, this is
-                                    // what's shown in the Hydra UI.
-                                    writeLine(to->get(), "restart");
-                                }
-                            });
-                        from = std::move(fromPipe.readSide);
-                        to = std::move(toPipe.writeSide);
-                        debug("created worker process %d", pid.get());
-                    }
-
-                    /* Check whether the existing worker process is still there. */
-                    auto s = readLine(from.get());
-                    if (s == "restart") {
-                        pid.wait();
-                        continue;
-                    } else if (s != "next") {
-                        auto json = nlohmann::json::parse(s);
-                        throw Error("worker error: %s", (std::string) json["error"]);
-                    }
-
-                    /* Wait for a job name to become available. */
-                    std::string attrPath;
-
-                    while (true) {
-                        checkInterrupt();
-                        auto state(state_.lock());
-                        if ((state->todo.empty() && state->active.empty()) || state->exc) {
-                            writeLine(to.get(), "exit");
-                            return;
-                        }
-                        if (!state->todo.empty()) {
-                            attrPath = *state->todo.begin();
-                            state->todo.erase(state->todo.begin());
-                            state->active.insert(attrPath);
-                            break;
-                        } else
-                            state.wait(wakeup);
-                    }
-
-                    /* Tell the worker to evaluate it. */
-                    writeLine(to.get(), "do " + attrPath);
-
-                    /* Wait for the response. */
-                    auto response = nlohmann::json::parse(readLine(from.get()));
-
-                    /* Handle the response. */
-                    StringSet newAttrs;
-
-                    if (response.find("job") != response.end()) {
-                        auto state(state_.lock());
-                        state->jobs[attrPath] = response["job"];
-                    }
-
-                    if (response.find("attrs") != response.end()) {
-                        for (auto & i : response["attrs"]) {
-                            std::string path = i;
-                            if (path.find(".") != std::string::npos){
-                                path = "\"" + path  + "\"";
-                            }
-                            auto s = (attrPath.empty() ? "" : attrPath + ".") + (std::string) path;
-                            newAttrs.insert(s);
-                        }
-                    }
-
-                    if (response.find("error") != response.end()) {
-                        auto state(state_.lock());
-                        state->jobs[attrPath]["error"] = response["error"];
-                    }
-
-                    /* Add newly discovered job names to the queue. */
-                    {
-                        auto state(state_.lock());
-                        state->active.erase(attrPath);
-                        for (auto & s : newAttrs)
-                            state->todo.insert(s);
-                        wakeup.notify_all();
-                    }
-                }
-            } catch (...) {
-                check_pid_status_nonblocking(pid.release());
-                auto state(state_.lock());
-                state->exc = std::current_exception();
-                wakeup.notify_all();
-            }
-        };
-
-        std::vector<std::thread> threads;
-        for (size_t i = 0; i < nrWorkers; i++)
-            threads.emplace_back(std::thread(handler));
-
-        for (auto & thread : threads)
-            thread.join();
-
-        auto state(state_.lock());
-
-        if (state->exc)
-            std::rethrow_exception(state->exc);
-
-        /* For aggregate jobs that have named consistuents
-           (i.e. constituents that are a job name rather than a
-           derivation), look up the referenced job and add it to the
-           dependencies of the aggregate derivation. */
-        auto store = openStore();
-
-        for (auto i = state->jobs.begin(); i != state->jobs.end(); ++i) {
-            auto jobName = i.key();
-            auto & job = i.value();
-
-            auto named = job.find("namedConstituents");
-            if (named == job.end()) continue;
-
-            std::unordered_map<std::string, std::string> brokenJobs;
-            auto getNonBrokenJobOrRecordError = [&brokenJobs, &jobName, &state](
-                    const std::string & childJobName) -> std::optional<nlohmann::json> {
-                auto childJob = state->jobs.find(childJobName);
-                if (childJob == state->jobs.end()) {
-                    printError("aggregate job '%s' references non-existent job '%s'", jobName, childJobName);
-                    brokenJobs[childJobName] = "does not exist";
-                    return std::nullopt;
-                }
-                if (childJob->find("error") != childJob->end()) {
-                    std::string error = (*childJob)["error"];
-                    printError("aggregate job '%s' references broken job '%s': %s", jobName, childJobName, error);
-                    brokenJobs[childJobName] = error;
-                    return std::nullopt;
-                }
-                return *childJob;
-            };
-
-            if (myArgs.dryRun) {
-                for (std::string jobName2 : *named) {
-                    auto job2 = getNonBrokenJobOrRecordError(jobName2);
-                    if (!job2) {
-                        continue;
-                    }
-                    std::string drvPath2 = (*job2)["drvPath"];
-                    job["constituents"].push_back(drvPath2);
-                }
-            } else {
-                auto drvPath = store->parseStorePath((std::string) job["drvPath"]);
-                auto drv = store->readDerivation(drvPath);
-
-                for (std::string jobName2 : *named) {
-                    auto job2 = getNonBrokenJobOrRecordError(jobName2);
-                    if (!job2) {
-                        continue;
-                    }
-                    auto drvPath2 = store->parseStorePath((std::string) (*job2)["drvPath"]);
-                    auto drv2 = store->readDerivation(drvPath2);
-                    job["constituents"].push_back(store->printStorePath(drvPath2));
-                    drv.inputDrvs.map[drvPath2].value = {drv2.outputs.begin()->first};
-                }
-
-                if (brokenJobs.empty()) {
-                    std::string drvName(drvPath.name());
-                    assert(drvName.ends_with(drvExtension));
-                    drvName.resize(drvName.size() - drvExtension.size());
-
-                    auto hashModulo = hashDerivationModulo(*store, drv, true);
-                    if (hashModulo.kind != DrvHash::Kind::Regular) continue;
-                    auto h = hashModulo.hashes.find("out");
-                    if (h == hashModulo.hashes.end()) continue;
-                    auto outPath = store->makeOutputPath("out", h->second, drvName);
-                    drv.env["out"] = store->printStorePath(outPath);
-                    drv.outputs.insert_or_assign("out", DerivationOutput::InputAddressed { .path = outPath });
-                    auto newDrvPath = store->printStorePath(writeDerivation(*store, drv));
-
-                    debug("rewrote aggregate derivation %s -> %s", store->printStorePath(drvPath), newDrvPath);
-
-                    job["drvPath"] = newDrvPath;
-                    job["outputs"]["out"] = store->printStorePath(outPath);
-                }
-            }
-
-            job.erase("namedConstituents");
-
-            /* Register the derivation as a GC root.  !!! This
-                registers roots for jobs that we may have already
-                done. */
-            auto localStore = store.dynamic_pointer_cast<LocalFSStore>();
-            if (gcRootsDir != "" && localStore) {
-                auto drvPath = job["drvPath"].get<std::string>();
-                Path root = gcRootsDir + "/" + std::string(baseNameOf(drvPath));
-                if (!pathExists(root))
-                    localStore->addPermRoot(localStore->parseStorePath(drvPath), root);
-            }
-
-            if (!brokenJobs.empty()) {
-                std::stringstream ss;
-                for (const auto& [jobName, error] : brokenJobs) {
-                    ss << jobName << ": " << error << "\n";
-                }
-                job["error"] = ss.str();
-            }
-        }
-
-        std::cout << state->jobs.dump(2) << "\n";
-    });
-}

src/script/hydra-eval-jobset

@@ -357,22 +357,26 @@ sub evalJobs {
     my @cmd;
 
     if (defined $flakeRef) {
-        @cmd = ("hydra-eval-jobs",
-                "--flake", $flakeRef,
+        @cmd = ("nix-eval-jobs",
+                "--flake", $flakeRef . '#hydraJobs',
                 "--gc-roots-dir", getGCRootsDir,
-                "--max-jobs", 1);
+                "--max-jobs", 1,
+                "--meta",
+                "--force-recurse");
     } else {
         my $nixExprInput = $inputInfo->{$nixExprInputName}->[0]
             or die "cannot find the input containing the job expression\n";
 
-        @cmd = ("hydra-eval-jobs",
+        @cmd = ("nix-eval-jobs",
                 "<" . $nixExprInputName . "/" . $nixExprPath . ">",
                 "--gc-roots-dir", getGCRootsDir,
                 "--max-jobs", 1,
+                "--meta",
+                "--force-recurse",
                 inputsToArgs($inputInfo));
     }
 
-    push @cmd, "--no-allow-import-from-derivation" if $config->{allow_import_from_derivation} // "true" ne "true";
+    #push @cmd, "--no-allow-import-from-derivation" if $config->{allow_import_from_derivation} // "true" ne "true";
 
     if (defined $ENV{'HYDRA_DEBUG'}) {
         sub escape {
@@ -384,14 +388,23 @@ sub evalJobs {
         print STDERR "evaluator: @escaped\n";
     }
 
-    (my $res, my $jobsJSON, my $stderr) = captureStdoutStderr(21600, @cmd);
-    die "hydra-eval-jobs returned " . ($res & 127 ? "signal $res" : "exit code " . ($res >> 8))
+    (my $res, my $jobsJSONLines, my $stderr) = captureStdoutStderr(21600, @cmd);
+    die "nix-eval-jobs returned " . ($res & 127 ? "signal $res" : "exit code " . ($res >> 8))
         . ":\n" . ($stderr ? decode("utf-8", $stderr) : "(no output)\n")
         if $res;
 
     print STDERR "$stderr";
 
-    return decode_json($jobsJSON);
+    # XXX: take advantage of nix-eval-jobs's streaming instead of parsing everything in one block at
+    # the end.
+    my @jobs;
+    foreach my $line (split(/\n/, $jobsJSONLines)) {
+      last if $line eq "";
+
+      push(@jobs, decode_json($line));
+    };
+
+    return @jobs;
 }
 
 
@@ -420,7 +433,7 @@ sub checkBuild {
     my $firstOutputName = $outputNames[0];
     my $firstOutputPath = $buildInfo->{outputs}->{$firstOutputName};
 
-    my $jobName = $buildInfo->{jobName} or die;
+    my $jobName = $buildInfo->{attr} or die;
     my $drvPath = $buildInfo->{drvPath} or die;
 
     my $build;
@@ -474,9 +487,30 @@ sub checkBuild {
 
         my $time = time();
 
-        sub null {
-            my ($s) = @_;
-            return $s eq "" ? undef : $s;
+        sub getMeta {
+            my ($s, $def) = @_;
+            return ($s || "") eq "" ? $def : $s;
+        }
+
+        sub getMetaStrings {
+            my ($v, $k, $acc) = @_;
+            my $t = ref $v;
+
+            if ($t eq 'HASH') {
+                push @$acc, $v->{$k} if exists $v->{$k};
+            } elsif ($t eq 'ARRAY') {
+                getMetaStrings($_, $k, $acc) foreach @$v;
+            } elsif (defined $v) {
+                push @$acc, $v;
+            }
+        }
+
+        sub getMetaConcatStrings {
+            my ($v, $k) = @_;
+
+            my @strings;
+            getMetaStrings($v, $k, \@strings);
+            return join(", ", @strings) || undef;
         }
 
         # Add the build to the database.
@@ -484,19 +518,19 @@ sub checkBuild {
             { timestamp => $time
             , jobset_id => $jobset->id
             , job => $jobName
-            , description => null($buildInfo->{description})
-            , license => null($buildInfo->{license})
-            , homepage => null($buildInfo->{homepage})
-            , maintainers => null($buildInfo->{maintainers})
-            , maxsilent => $buildInfo->{maxSilent}
-            , timeout => $buildInfo->{timeout}
-            , nixname => $buildInfo->{nixName}
+            , description => getMeta($buildInfo->{meta}->{description}, undef)
+            , license => getMetaConcatStrings($buildInfo->{meta}->{license}, "shortName")
+            , homepage => getMeta($buildInfo->{meta}->{homepage}, undef)
+            , maintainers => getMetaConcatStrings($buildInfo->{meta}->{maintainers}, "email")
+            , maxsilent => getMeta($buildInfo->{meta}->{maxSilent}, 7200)
+            , timeout => getMeta($buildInfo->{meta}->{timeout}, 36000)
+            , nixname => $buildInfo->{name}
             , drvpath => $drvPath
             , system => $buildInfo->{system}
-            , priority => $buildInfo->{schedulingPriority}
+            , priority => getMeta($buildInfo->{meta}->{schedulingPriority}, 100)
             , finished => 0
             , iscurrent => 1
-            , ischannel => $buildInfo->{isChannel}
+            , ischannel => getMeta($buildInfo->{meta}->{isChannel}, 0)
             });
 
         $build->buildoutputs->create({ name => $_, path => $buildInfo->{outputs}->{$_} })
@@ -665,7 +699,7 @@ sub checkJobsetWrapped {
         return;
     }
 
-    # Hash the arguments to hydra-eval-jobs and check the
+    # Hash the arguments to nix-eval-jobs and check the
     # JobsetInputHashes to see if the previous evaluation had the same
     # inputs.  If so, bail out.
     my @args = ($jobset->nixexprinput // "", $jobset->nixexprpath // "", inputsToArgs($inputInfo));
@@ -687,19 +721,18 @@ sub checkJobsetWrapped {
 
     # Evaluate the job expression.
     my $evalStart = clock_gettime(CLOCK_MONOTONIC);
-    my $jobs = evalJobs($project->name . ":" . $jobset->name, $inputInfo, $jobset->nixexprinput, $jobset->nixexprpath, $flakeRef);
+    my @jobs = evalJobs($project->name . ":" . $jobset->name, $inputInfo, $jobset->nixexprinput, $jobset->nixexprpath, $flakeRef);
     my $evalStop = clock_gettime(CLOCK_MONOTONIC);
 
     if ($jobsetsJobset) {
-        my @keys = keys %$jobs;
         die "The .jobsets jobset must only have a single job named 'jobsets'"
-            unless (scalar @keys) == 1 && $keys[0] eq "jobsets";
+            unless (scalar @jobs) == 1 && $jobs[0]->{attr} eq "jobsets";
     }
     Net::Statsd::timing("hydra.evaluator.eval_time", int(($evalStop - $evalStart) * 1000));
 
     if ($dryRun) {
-        foreach my $name (keys %{$jobs}) {
-            my $job = $jobs->{$name};
+        foreach my $job (@jobs) {
+            my $name = $job->{attr};
             if (defined $job->{drvPath}) {
                 print STDERR "good job $name: $job->{drvPath}\n";
             } else {
@@ -709,11 +742,6 @@ sub checkJobsetWrapped {
         return;
     }
 
-    die "Jobset contains a job with an empty name. Make sure the jobset evaluates to an attrset of jobs.\n"
-        if defined $jobs->{""};
-
-    $jobs->{$_}->{jobName} = $_ for keys %{$jobs};
-
     my $jobOutPathMap = {};
     my $jobsetChanged = 0;
     my $dbStart = clock_gettime(CLOCK_MONOTONIC);
@@ -722,10 +750,10 @@ sub checkJobsetWrapped {
     # Store the error messages for jobs that failed to evaluate.
     my $evaluationErrorTime = time;
     my $evaluationErrorMsg = "";
-    foreach my $job (values %{$jobs}) {
+    foreach my $job (@jobs) {
         next unless defined $job->{error};
         $evaluationErrorMsg .=
-            ($job->{jobName} ne "" ? "in job ‘$job->{jobName}’" : "at top-level") .
+            ($job->{attr} ne "" ? "in job ‘$job->{attr}’" : "at top-level") .
             ":\n" . $job->{error} . "\n\n";
     }
     setJobsetError($jobset, $evaluationErrorMsg, $evaluationErrorTime);
@@ -760,7 +788,7 @@ sub checkJobsetWrapped {
             });
 
         # Schedule each successfully evaluated job.
-        foreach my $job (permute(values %{$jobs})) {
+        foreach my $job (permute(@jobs)) {
             next if defined $job->{error};
             #print STDERR "considering job " . $project->name, ":", $jobset->name, ":", $job->{jobName} . "\n";
             checkBuild($db, $jobset, $ev, $inputInfo, $job, \%buildMap, $prevEval, $jobOutPathMap, $plugins);
@@ -786,40 +814,6 @@ sub checkJobsetWrapped {
                 $ev->jobsetevalmembers->create({ build => $id, isnew => $x->{new} });
             }
 
-            # Create AggregateConstituents mappings.  Since there can
-            # be jobs that alias each other, if there are multiple
-            # builds for the same derivation, pick the one with the
-            # shortest name.
-            my %drvPathToId;
-            foreach my $id (keys %buildMap) {
-                my $x = $buildMap{$id};
-                my $y = $drvPathToId{$x->{drvPath}};
-                if (defined $y) {
-                    next if length $x->{jobName} > length $y->{jobName};
-                    next if length $x->{jobName} == length $y->{jobName} && $x->{jobName} ge $y->{jobName};
-                }
-                $drvPathToId{$x->{drvPath}} = $x;
-            }
-
-            foreach my $job (values %{$jobs}) {
-                next unless $job->{constituents};
-
-                if (defined $job->{error}) {
-                    die "aggregate job ‘$job->{jobName}’ failed with the error: $job->{error}\n";
-                }
-
-                my $x = $drvPathToId{$job->{drvPath}} or
-                    die "aggregate job ‘$job->{jobName}’ has no corresponding build record.\n";
-                foreach my $drvPath (@{$job->{constituents}}) {
-                    my $constituent = $drvPathToId{$drvPath};
-                    if (defined $constituent) {
-                        $db->resultset('AggregateConstituents')->update_or_create({aggregate => $x->{id}, constituent => $constituent->{id}});
-                    } else {
-                        warn "aggregate job ‘$job->{jobName}’ has a constituent ‘$drvPath’ that doesn't correspond to a Hydra build\n";
-                    }
-                }
-            }
-
             foreach my $name (keys %{$inputInfo}) {
                 for (my $n = 0; $n < scalar(@{$inputInfo->{$name}}); $n++) {
                     my $input = $inputInfo->{$name}->[$n];

t/Hydra/Controller/Build/api.t

@@ -78,28 +78,4 @@ subtest "validating the JSON representation of a build" => sub {
     }, "The build's JSON matches our API.");
 };
 
-subtest "accessing the constituents API" => sub {
-    my $url = $build_url . "/constituents";
-
-    my $constituents = request(GET $url,
-        Accept => 'application/json',
-    );
-
-    ok($constituents->is_success, "Getting the constituent builds");
-
-    my $data;
-    my $valid_json = lives { $data = decode_json($constituents->content); };
-    ok($valid_json, "We get back valid JSON.");
-    if (!$valid_json) {
-        use Data::Dumper;
-        print STDERR Dumper $constituents->content;
-    }
-
-    my ($buildA) = grep { $_->{nixname} eq "empty-dir-a" } @$data;
-    my ($buildB) = grep { $_->{nixname} eq "empty-dir-b" } @$data;
-
-    is($buildA->{job}, "a");
-    is($buildB->{job}, "b");
-};
-
 done_testing;

t/Makefile.am

@@ -13,7 +13,7 @@ TESTS_ENVIRONMENT = \
   PGHOST=/tmp	\
   PERL5LIB="$(srcdir):$(abs_top_srcdir)/src/lib:$$PERL5LIB"	\
   PYTHONPATH= \
-  PATH=$(abs_top_srcdir)/src/hydra-evaluator:$(abs_top_srcdir)/src/script:$(abs_top_srcdir)/src/hydra-eval-jobs:$(abs_top_srcdir)/src/hydra-queue-runner:$$PATH \
+  PATH=$(abs_top_srcdir)/src/hydra-evaluator:$(abs_top_srcdir)/src/script:$(abs_top_srcdir)/src/hydra-queue-runner:$$PATH \
   perl -w
 
 EXTRA_DIST = \

t/evaluator/evaluate-constituents-broken.t

@@ -1,32 +0,0 @@
-use strict;
-use warnings;
-use Setup;
-use Test2::V0;
-use Hydra::Helper::Exec;
-
-my $ctx = test_context();
-
-my $jobsetCtx = $ctx->makeJobset(
-    expression => 'constituents-broken.nix',
-);
-my $jobset = $jobsetCtx->{"jobset"};
-
-my ($res, $stdout, $stderr) = captureStdoutStderr(60,
-    ("hydra-eval-jobset", $jobsetCtx->{"project"}->name, $jobset->name)
-);
-isnt($res, 0, "hydra-eval-jobset exits non-zero");
-ok(utf8::decode($stderr), "Stderr output is UTF8-clean");
-like(
-    $stderr,
-    qr/aggregate job ‘mixed_aggregate’ failed with the error: constituentA: does not exist/,
-    "The stderr record includes a relevant error message"
-);
-
-$jobset->discard_changes({ '+columns' => {'errormsg' => 'errormsg'} });  # refresh from DB
-like(
-    $jobset->errormsg,
-    qr/aggregate job ‘mixed_aggregate’ failed with the error: constituentA: does not exist/,
-    "The jobset records a relevant error message"
-);
-
-done_testing;

t/evaluator/evaluate-constituents-gc.t

@@ -1,20 +0,0 @@
-use strict;
-use warnings;
-use Setup;
-use Test2::V0;
-
-my $ctx = test_context();
-
-my $builds = $ctx->makeAndEvaluateJobset(
-    expression => 'constituents.nix',
-);
-
-my $constituentA = $builds->{"constituentA"};
-my $directAggregate = $builds->{"direct_aggregate"};
-my $indirectAggregate = $builds->{"indirect_aggregate"};
-
-is(system('nix-store', '--delete', $constituentA->drvpath), 256, "Deleting a constituent derivation fails");
-is(system('nix-store', '--delete', $directAggregate->drvpath), 256, "Deleting the direct aggregate derivation fails");
-is(system('nix-store', '--delete', $indirectAggregate->drvpath), 256, "Deleting the indirect aggregate derivation fails");
-
-done_testing;

t/evaluator/evaluate-meta.t

@@ -0,0 +1,22 @@
+use feature 'unicode_strings';
+use strict;
+use warnings;
+use Setup;
+use Test2::V0;
+
+my $ctx = test_context();
+
+my $builds = $ctx->makeAndEvaluateJobset(
+    expression => "meta.nix",
+    build => 1
+);
+
+my $build = $builds->{"full-of-meta"};
+
+is($build->finished, 1, "Build should be finished.");
+is($build->description, "This is the description of the job.", "Wrong description extracted from the build.");
+is($build->license, "MIT, BSD", "Wrong licenses extracted from the build.");
+is($build->homepage, "https://example.com/", "Wrong homepage extracted from the build.");
+is($build->maintainers, 'alice@example.com, bob@not.found', "Wrong maintainers extracted from the build.");
+
+done_testing;

t/evaluator/evaluate-oom-job.t

@@ -1,63 +0,0 @@
-use strict;
-use warnings;
-use Setup;
-use Test2::V0;
-use Hydra::Helper::Exec;
-
-# Ensure that `systemd-run` is
-# - Available in the PATH/envionment
-# - Accessable to the user executing it
-# - Capable of using the command switches we use in our test
-my $sd_res;
-eval {
-  ($sd_res) = captureStdoutStderr(3, (
-    "systemd-run",
-      "--user",
-      "--collect",
-      "--scope",
-      "--property",
-        "MemoryMax=25M",
-    "--",
-    "true"
-  ));
-} or do {
-  # The command failed to execute, likely because `systemd-run` is not present
-  # in `PATH`
-  skip_all("`systemd-run` failed when invoked in this environment");
-};
-if ($sd_res != 0) {
-  # `systemd-run` executed but `sytemd-run` failed to call `true` and return
-  # successfully
-  skip_all("`systemd-run` returned non-zero when executing `true` (expected 0)");
-}
-
-my $ctx = test_context();
-
-# Contain the memory usage to 25 MegaBytes using `systemd-run`
-# Run `hydra-eval-jobs` on test job that will purposefully consume all memory
-# available
-my ($res, $stdout, $stderr) = captureStdoutStderr(60, (
-  "systemd-run",
-    "--user",
-    "--collect",
-    "--scope",
-    "--property",
-      "MemoryMax=25M",
-  "--",
-  "hydra-eval-jobs",
-    "-I", "/dev/zero",
-    "-I", $ctx->jobsdir,
-    ($ctx->jobsdir . "/oom.nix")
-));
-
-isnt($res, 0, "`hydra-eval-jobs` exits non-zero");
-ok(utf8::decode($stderr), "Stderr output is UTF8-clean");
-like(
-  $stderr,
-  # Assert error log contains messages added in PR
-  # https://github.com/NixOS/hydra/pull/1203
-  qr/^child process \(\d+?\) killed by signal=9$/m,
-  "The stderr record includes a relevant error message"
-);
-
-done_testing;

t/jobs/meta.nix

@@ -0,0 +1,17 @@
+with import ./config.nix;
+{
+  full-of-meta =
+    mkDerivation {
+      name = "full-of-meta";
+      builder = ./empty-dir-builder.sh;
+
+      meta = {
+        description = "This is the description of the job.";
+        license = [ { shortName = "MIT"; } "BSD" ];
+        homepage = "https://example.com/";
+        maintainers = [ "alice@example.com" { email = "bob@not.found"; } ];
+
+        outPath = "${placeholder "out"}";
+      };
+    };
+}

t/queue-runner/constituents.t

@@ -1,32 +0,0 @@
-use feature 'unicode_strings';
-use strict;
-use warnings;
-use Setup;
-
-my %ctx = test_init();
-
-require Hydra::Schema;
-require Hydra::Model::DB;
-
-use Test2::V0;
-
-my $db = Hydra::Model::DB->new;
-hydra_setup($db);
-
-my $project = $db->resultset('Projects')->create({name => "tests", displayname => "", owner => "root"});
-
-my $jobset = createBaseJobset("broken-constituent", "broken-constituent.nix", $ctx{jobsdir});
-
-ok(evalSucceeds($jobset),               "Evaluating jobs/broken-constituent.nix should exit with return code 0");
-is(nrQueuedBuildsForJobset($jobset), 0, "Evaluating jobs/broken-constituent.nix should not queue any builds");
-
-like(
-    $jobset->errormsg,
-    qr/^does-not-exist: does not exist$/m,
-    "Evaluating jobs/broken-constituent.nix should log an error for does-not-exist");
-like(
-    $jobset->errormsg,
-    qr/^does-not-evaluate: error: assertion 'false' failed$/m,
-    "Evaluating jobs/broken-constituent.nix should log an error for does-not-evaluate");
-
-done_testing;

t/queue-runner/direct-indirect-constituents.t

@@ -1,35 +0,0 @@
-use strict;
-use warnings;
-use Setup;
-use Test2::V0;
-
-my $ctx = test_context();
-
-my $builds = $ctx->makeAndEvaluateJobset(
-    expression => 'constituents.nix',
-);
-
-my $constituentBuildA = $builds->{"constituentA"};
-my $constituentBuildB = $builds->{"constituentB"};
-
-my $eval = $constituentBuildA->jobsetevals->first();
-is($eval->evaluationerror->has_error, 0);
-
-subtest "Verifying the direct aggregate" => sub {
-    my $aggBuild = $builds->{"direct_aggregate"};
-    is($aggBuild->constituents->first()->id, $constituentBuildA->id, "The ID of the constituent is correct");
-};
-
-subtest "Verifying the indirect aggregate" => sub {
-    my $indirectBuild = $builds->{"indirect_aggregate"};
-    is($indirectBuild->constituents->first()->id, $constituentBuildA->id, "The ID of the constituent is correct");
-};
-
-subtest "Verifying a mix of direct and indirect aggregate references" => sub {
-    my $mixedBuild = $builds->{"mixed_aggregate"};
-    my ($constituentA, $constituentB) = $mixedBuild->constituents()->search({}, {order_by => { -asc => "job"} });
-    is($constituentA->id, $constituentBuildA->id, "The ID of the constituent is correct");
-    is($constituentB->id, $constituentBuildB->id, "The ID of the constituent is correct");
-};
-
-done_testing;