Merge pull request #1459 from dermetfan/fix-1429-backport-nix-2.25

(backport to nix-2.25) hydra-eval-jobset: do not wait on n-e-j inside transaction

flake.lock

@@ -32,20 +32,36 @@
         "nixpkgs-regression": []
       },
       "locked": {
-        "lastModified": 1726787955,
-        "narHash": "sha256-XFznzb8L4SdUm9u+w3DPpMWJhffuv+/6+aiVl00slns=",
+        "lastModified": 1739390454,
+        "narHash": "sha256-mIpJgIwPS4o4xYhN1B+/fHESEXoxpu6nVoZTzZ0MfTg=",
         "owner": "NixOS",
         "repo": "nix",
-        "rev": "a7fdef6858dd45b9d7bda7c92324c63faee7f509",
+        "rev": "d652513e4519ed4eb48c92f8670e5a71c7793fc3",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "2.24-maintenance",
+        "ref": "2.25-maintenance",
         "repo": "nix",
         "type": "github"
       }
     },
+    "nix-eval-jobs": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1739426028,
+        "narHash": "sha256-1dZLPw+nlFQzzswfyTxW+8VF1AJ4ZvoYvLTjlHiz1SA=",
+        "owner": "nix-community",
+        "repo": "nix-eval-jobs",
+        "rev": "6d4fd5a93d7bc953ffa4dcd6d53ad7056a71eff7",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "repo": "nix-eval-jobs",
+        "type": "github"
+      }
+    },
     "nixpkgs": {
       "locked": {
         "lastModified": 1726688310,
@@ -66,6 +82,7 @@
       "inputs": {
         "libgit2": "libgit2",
         "nix": "nix",
+        "nix-eval-jobs": "nix-eval-jobs",
         "nixpkgs": "nixpkgs"
       }
     }

flake.nix

@@ -3,19 +3,31 @@
 
   inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.05-small";
 
-  inputs.libgit2 = { url = "github:libgit2/libgit2/v1.8.1"; flake = false; };
-  inputs.nix.url = "github:NixOS/nix/2.24-maintenance";
-  inputs.nix.inputs.nixpkgs.follows = "nixpkgs";
-  inputs.nix.inputs.libgit2.follows = "libgit2";
+  inputs.libgit2 = {
+    url = "github:libgit2/libgit2/v1.8.1";
+    flake = false;
+  };
 
-  # hide nix dev tooling from our lock file
-  inputs.nix.inputs.flake-parts.follows = "";
-  inputs.nix.inputs.git-hooks-nix.follows = "";
-  inputs.nix.inputs.nixpkgs-regression.follows = "";
-  inputs.nix.inputs.nixpkgs-23-11.follows = "";
-  inputs.nix.inputs.flake-compat.follows = "";
+  inputs.nix = {
+    url = "github:NixOS/nix/2.25-maintenance";
+    inputs.nixpkgs.follows = "nixpkgs";
+    inputs.libgit2.follows = "libgit2";
 
-  outputs = { self, nixpkgs, nix, ... }:
+    # hide nix dev tooling from our lock file
+    inputs.flake-parts.follows = "";
+    inputs.git-hooks-nix.follows = "";
+    inputs.nixpkgs-regression.follows = "";
+    inputs.nixpkgs-23-11.follows = "";
+    inputs.flake-compat.follows = "";
+  };
+
+  inputs.nix-eval-jobs = {
+    url = "github:nix-community/nix-eval-jobs";
+    # We want to control the deps precisely
+    flake = false;
+  };
+
+  outputs = { self, nixpkgs, nix, nix-eval-jobs, ... }:
     let
       systems = [ "x86_64-linux" "aarch64-linux" ];
       forEachSystem = nixpkgs.lib.genAttrs systems;
@@ -24,6 +36,7 @@
 
       # A Nixpkgs overlay that provides a 'hydra' package.
       overlays.default = final: prev: {
+        nix-eval-jobs = final.callPackage nix-eval-jobs {};
         hydra = final.callPackage ./package.nix {
           inherit (nixpkgs.lib) fileset;
           rawSrc = self;
@@ -67,8 +80,12 @@
       });
 
       packages = forEachSystem (system: {
+        nix-eval-jobs = nixpkgs.legacyPackages.${system}.callPackage nix-eval-jobs {
+          nix = nix.packages.${system}.nix;
+        };
         hydra = nixpkgs.legacyPackages.${system}.callPackage ./package.nix {
           inherit (nixpkgs.lib) fileset;
+          inherit (self.packages.${system}) nix-eval-jobs;
           rawSrc = self;
           nix = nix.packages.${system}.nix;
           nix-perl-bindings = nix.hydraJobs.perlBindings.${system};

package.nix

@@ -50,6 +50,7 @@
 , xz
 , gnutar
 , gnused
+, nix-eval-jobs
 
 , rpm
 , dpkg
@@ -190,6 +191,7 @@ stdenv.mkDerivation (finalAttrs: {
     openldap
     postgresql_13
     pixz
+    nix-eval-jobs
   ];
 
   checkInputs = [
@@ -218,6 +220,7 @@ stdenv.mkDerivation (finalAttrs: {
       darcs
       gnused
       breezy
+      nix-eval-jobs
     ] ++ lib.optionals stdenv.isLinux [ rpm dpkg cdrkit ]
   );
 
@@ -232,7 +235,7 @@ 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
@@ -263,7 +266,8 @@ stdenv.mkDerivation (finalAttrs: {
             --prefix PATH ':' $out/bin:$hydraPath \
             --set HYDRA_RELEASE ${version} \
             --set HYDRA_HOME $out/libexec/hydra \
-            --set NIX_RELEASE ${nix.name or "unknown"}
+            --set NIX_RELEASE ${nix.name or "unknown"} \
+            --set NIX_EVAL_JOBS_RELEASE ${nix-eval-jobs.name or "unknown"}
     done
   '';
 

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

@@ -1,587 +0,0 @@
-#include <iostream>
-#include <thread>
-#include <optional>
-#include <unordered_map>
-
-#include "shared.hh"
-#include "store-api.hh"
-#include "eval.hh"
-#include "eval-gc.hh"
-#include "eval-inline.hh"
-#include "eval-settings.hh"
-#include "signals.hh"
-#include "terminal.hh"
-#include "util.hh"
-#include "get-drvs.hh"
-#include "globals.hh"
-#include "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, PackageInfo & 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.emplace_back(v.string_view());
-        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, fragment, outputSpec] = parseFlakeRefWithFragmentAndExtendedOutputsSpec(fetchSettings, myArgs.releaseExpr, absPath("."));
-
-        auto vFlake = state.allocValue();
-
-        auto lockedFlake = lockFlake(
-                flakeSettings,
-                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 (!hasPrefix(s, "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.
-                PackageInfo::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->string_view());
-                    }
-                }
-
-                /* 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_t pid = -1;
-            try {
-                AutoCloseFD from, to;
-
-                while (true) {
-
-                    /* Start a new worker process if necessary. */
-                    if (pid == -1) {
-                        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 {
-                                    auto evalStore = myArgs.evalStoreUrl
-                                             ? openStore(*myArgs.evalStoreUrl)
-                                             : openStore();
-                                    EvalState state(myArgs.lookupPath,
-                                            evalStore, fetchSettings, evalSettings);
-                                    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");
-                                }
-                            },
-                            ProcessOptions { .allowVfork = false });
-                        from = std::move(fromPipe.readSide);
-                        to = std::move(toPipe.writeSide);
-                        debug("created worker process %d", pid);
-                    }
-
-                    /* Check whether the existing worker process is still there. */
-                    auto s = readLine(from.get());
-                    if (s == "restart") {
-                        pid = -1;
-                        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);
-                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(hasSuffix(drvName, 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/hydra-eval-jobs/meson.build

@@ -1,8 +0,0 @@
-hydra_eval_jobs = executable('hydra-eval-jobs',
-  'hydra-eval-jobs.cc',
-  dependencies: [
-    libhydra_dep,
-    nix_dep,
-  ],
-  install: true,
-)

src/hydra-queue-runner/build-remote.cc

@@ -7,6 +7,7 @@
 
 #include "build-result.hh"
 #include "path.hh"
+#include "legacy-ssh-store.hh"
 #include "serve-protocol.hh"
 #include "serve-protocol-impl.hh"
 #include "state.hh"
@@ -21,28 +22,23 @@
 
 using namespace nix;
 
-namespace nix::build_remote {
-
-static Strings extraStoreArgs(std::string & machine)
+bool ::Machine::isLocalhost() const
 {
-    Strings result;
-    try {
-        auto parsed = parseURL(machine);
-        if (parsed.scheme != "ssh") {
-            throw SysError("Currently, only (legacy-)ssh stores are supported!");
-        }
-        machine = parsed.authority.value_or("");
-        auto remoteStore = parsed.query.find("remote-store");
-        if (remoteStore != parsed.query.end()) {
-            result = {"--store", shellEscape(remoteStore->second)};
-        }
-    } catch (BadURL &) {
-        // We just try to continue with `machine->sshName` here for backwards compat.
-    }
-
-    return result;
+    return storeUri.params.empty() && std::visit(overloaded {
+        [](const StoreReference::Auto &) {
+            return true;
+        },
+        [](const StoreReference::Specified & s) {
+            return
+               (s.scheme == "local" || s.scheme == "unix") ||
+               ((s.scheme == "ssh" || s.scheme == "ssh-ng") &&
+                s.authority == "localhost");
+        },
+    }, storeUri.variant);
 }
 
+namespace nix::build_remote {
+
 static std::unique_ptr<SSHMaster::Connection> openConnection(
     ::Machine::ptr machine, SSHMaster & master)
 {
@@ -51,7 +47,11 @@ static std::unique_ptr<SSHMaster::Connection> openConnection(
         command.push_back("--builders");
         command.push_back("");
     } else {
-        command.splice(command.end(), extraStoreArgs(machine->sshName));
+        auto remoteStore = machine->storeUri.params.find("remote-store");
+        if (remoteStore != machine->storeUri.params.end()) {
+            command.push_back("--store");
+            command.push_back(shellEscape(remoteStore->second));
+        }
     }
 
     auto ret = master.startCommand(std::move(command), {
@@ -198,7 +198,7 @@ static BasicDerivation sendInputs(
         MaintainCount<counter> mc2(nrStepsCopyingTo);
 
         printMsg(lvlDebug, "sending closure of ‘%s’ to ‘%s’",
-            localStore.printStorePath(step.drvPath), conn.machine->sshName);
+            localStore.printStorePath(step.drvPath), conn.machine->storeUri.render());
 
         auto now1 = std::chrono::steady_clock::now();
 
@@ -278,32 +278,6 @@ static BuildResult performBuild(
     return result;
 }
 
-static std::map<StorePath, UnkeyedValidPathInfo> queryPathInfos(
-    ::Machine::Connection & conn,
-    Store & localStore,
-    StorePathSet & outputs,
-    size_t & totalNarSize
-)
-{
-
-    /* Get info about each output path. */
-    std::map<StorePath, UnkeyedValidPathInfo> infos;
-    conn.to << ServeProto::Command::QueryPathInfos;
-    ServeProto::write(localStore, conn, outputs);
-    conn.to.flush();
-    while (true) {
-        auto storePathS = readString(conn.from);
-        if (storePathS == "") break;
-
-        auto storePath = localStore.parseStorePath(storePathS);
-        auto info = ServeProto::Serialise<UnkeyedValidPathInfo>::read(localStore, conn);
-        totalNarSize += info.narSize;
-        infos.insert_or_assign(std::move(storePath), std::move(info));
-    }
-
-    return infos;
-}
-
 static void copyPathFromRemote(
     ::Machine::Connection & conn,
     NarMemberDatas & narMembers,
@@ -430,15 +404,23 @@ void State::buildRemote(ref<Store> destStore,
 
         updateStep(ssConnecting);
 
-        SSHMaster master {
-            machine->sshName,
-            machine->sshKey,
-            machine->sshPublicHostKey,
-            false, // no SSH master yet
-            false, // no compression yet
-            logFD.get(),
+        auto storeRef = machine->completeStoreReference();
+
+        auto * pSpecified = std::get_if<StoreReference::Specified>(&storeRef.variant);
+        if (!pSpecified || pSpecified->scheme != "ssh") {
+            throw Error("Currently, only (legacy-)ssh stores are supported!");
+        }
+
+        LegacySSHStoreConfig storeConfig {
+            pSpecified->scheme,
+            pSpecified->authority,
+            storeRef.params
         };
 
+        auto master = storeConfig.createSSHMaster(
+            false, // no SSH master yet
+            logFD.get());
+
         // FIXME: rewrite to use Store.
         auto child = build_remote::openConnection(machine, master);
 
@@ -482,19 +464,13 @@ void State::buildRemote(ref<Store> destStore,
                 conn.to,
                 conn.from,
                 our_version,
-                machine->sshName);
+                machine->storeUri.render());
         } catch (EndOfFile & e) {
             child->sshPid.wait();
             std::string s = chomp(readFile(result.logFile));
-            throw Error("cannot connect to ‘%1%’: %2%", machine->sshName, s);
+            throw Error("cannot connect to ‘%1%’: %2%", machine->storeUri.render(), s);
         }
 
-        // Do not attempt to speak a newer version of the protocol.
-        //
-        // Per https://github.com/NixOS/nix/issues/9584 should be handled as
-        // part of `handshake` in upstream nix.
-        conn.remoteVersion = std::min(conn.remoteVersion, our_version);
-
         {
             auto info(machine->state->connectInfo.lock());
             info->consecutiveFailures = 0;
@@ -523,7 +499,7 @@ void State::buildRemote(ref<Store> destStore,
         /* Do the build. */
         printMsg(lvlDebug, "building ‘%s’ on ‘%s’",
             localStore->printStorePath(step->drvPath),
-            machine->sshName);
+            machine->storeUri.render());
 
         updateStep(ssBuilding);
 
@@ -546,7 +522,7 @@ void State::buildRemote(ref<Store> destStore,
            get a build log. */
         if (result.isCached) {
             printMsg(lvlInfo, "outputs of ‘%s’ substituted or already valid on ‘%s’",
-                localStore->printStorePath(step->drvPath), machine->sshName);
+                localStore->printStorePath(step->drvPath), machine->storeUri.render());
             unlink(result.logFile.c_str());
             result.logFile = "";
         }
@@ -563,8 +539,10 @@ void State::buildRemote(ref<Store> destStore,
 
             auto now1 = std::chrono::steady_clock::now();
 
+            auto infos = conn.queryPathInfos(*localStore, outputs);
+
             size_t totalNarSize = 0;
-            auto infos = build_remote::queryPathInfos(conn, *localStore, outputs, totalNarSize);
+            for (auto & [_, info] : infos) totalNarSize += info.narSize;
 
             if (totalNarSize > maxOutputSize) {
                 result.stepStatus = bsNarSizeLimitExceeded;
@@ -573,7 +551,7 @@ void State::buildRemote(ref<Store> destStore,
 
             /* Copy each path. */
             printMsg(lvlDebug, "copying outputs of ‘%s’ from ‘%s’ (%d bytes)",
-                localStore->printStorePath(step->drvPath), machine->sshName, totalNarSize);
+                localStore->printStorePath(step->drvPath), machine->storeUri.render(), totalNarSize);
 
             build_remote::copyPathsFromRemote(conn, narMembers, *localStore, *destStore, infos);
             auto now2 = std::chrono::steady_clock::now();
@@ -612,7 +590,7 @@ void State::buildRemote(ref<Store> destStore,
             info->consecutiveFailures = std::min(info->consecutiveFailures + 1, (unsigned int) 4);
             info->lastFailure = now;
             int delta = retryInterval * std::pow(retryBackoff, info->consecutiveFailures - 1) + (rand() % 30);
-            printMsg(lvlInfo, "will disable machine ‘%1%’ for %2%s", machine->sshName, delta);
+            printMsg(lvlInfo, "will disable machine ‘%1%’ for %2%s", machine->storeUri.render(), delta);
             info->disabledUntil = now + std::chrono::seconds(delta);
         }
         throw;

src/hydra-queue-runner/builder.cc

@@ -41,7 +41,7 @@ void State::builder(MachineReservation::ptr reservation)
         } catch (std::exception & e) {
             printMsg(lvlError, "uncaught exception building ‘%s’ on ‘%s’: %s",
                 localStore->printStorePath(reservation->step->drvPath),
-                reservation->machine->sshName,
+                reservation->machine->storeUri.render(),
                 e.what());
         }
     }
@@ -150,7 +150,7 @@ State::StepResult State::doBuildStep(nix::ref<Store> destStore,
         buildOptions.buildTimeout = build->buildTimeout;
 
         printInfo("performing step ‘%s’ %d times on ‘%s’ (needed by build %d and %d others)",
-            localStore->printStorePath(step->drvPath), buildOptions.nrRepeats + 1, machine->sshName, buildId, (dependents.size() - 1));
+            localStore->printStorePath(step->drvPath), buildOptions.nrRepeats + 1, machine->storeUri.render(), buildId, (dependents.size() - 1));
     }
 
     if (!buildOneDone)
@@ -178,7 +178,7 @@ State::StepResult State::doBuildStep(nix::ref<Store> destStore,
                     unlink(result.logFile.c_str());
                 }
             } catch (...) {
-                ignoreException();
+                ignoreExceptionInDestructor();
             }
         }
     });
@@ -196,7 +196,7 @@ State::StepResult State::doBuildStep(nix::ref<Store> destStore,
         {
             auto mc = startDbUpdate();
             pqxx::work txn(*conn);
-            stepNr = createBuildStep(txn, result.startTime, buildId, step, machine->sshName, bsBusy);
+            stepNr = createBuildStep(txn, result.startTime, buildId, step, machine->storeUri.render(), bsBusy);
             txn.commit();
         }
 
@@ -253,7 +253,7 @@ State::StepResult State::doBuildStep(nix::ref<Store> destStore,
     /* Finish the step in the database. */
     if (stepNr) {
         pqxx::work txn(*conn);
-        finishBuildStep(txn, result, buildId, stepNr, machine->sshName);
+        finishBuildStep(txn, result, buildId, stepNr, machine->storeUri.render());
         txn.commit();
     }
 
@@ -261,7 +261,7 @@ State::StepResult State::doBuildStep(nix::ref<Store> destStore,
        issue). Retry a number of times. */
     if (result.canRetry) {
         printMsg(lvlError, "possibly transient failure building ‘%s’ on ‘%s’: %s",
-            localStore->printStorePath(step->drvPath), machine->sshName, result.errorMsg);
+            localStore->printStorePath(step->drvPath), machine->storeUri.render(), result.errorMsg);
         assert(stepNr);
         bool retry;
         {
@@ -452,7 +452,7 @@ void State::failStep(
                     build->finishedInDB)
                     continue;
                 createBuildStep(txn,
-                    0, build->id, step, machine ? machine->sshName : "",
+                    0, build->id, step, machine ? machine->storeUri.render() : "",
                     result.stepStatus, result.errorMsg, buildId == build->id ? 0 : buildId);
             }
 

src/hydra-queue-runner/dispatcher.cc

@@ -256,7 +256,7 @@ system_time State::doDispatch()
                 /* Can this machine do this step? */
                 if (!mi.machine->supportsStep(step)) {
                     debug("machine '%s' does not support step '%s' (system type '%s')",
-                        mi.machine->sshName, localStore->printStorePath(step->drvPath), step->drv->platform);
+                        mi.machine->storeUri.render(), localStore->printStorePath(step->drvPath), step->drv->platform);
                     continue;
                 }
 

src/hydra-queue-runner/hydra-queue-runner.cc

@@ -135,65 +135,26 @@ void State::parseMachines(const std::string & contents)
         oldMachines = *machines_;
     }
 
-    for (auto line : tokenizeString<Strings>(contents, "\n")) {
-        line = trim(std::string(line, 0, line.find('#')));
-        auto tokens = tokenizeString<std::vector<std::string>>(line);
-        if (tokens.size() < 3) continue;
-        tokens.resize(8);
-
-        if (tokens[5] == "-") tokens[5] = "";
-        auto supportedFeatures = tokenizeString<StringSet>(tokens[5], ",");
-
-        if (tokens[6] == "-") tokens[6] = "";
-        auto mandatoryFeatures = tokenizeString<StringSet>(tokens[6], ",");
-
-        for (auto & f : mandatoryFeatures)
-            supportedFeatures.insert(f);
-
-        using MaxJobs = std::remove_const<decltype(nix::Machine::maxJobs)>::type;
-
-        auto machine = std::make_shared<::Machine>(nix::Machine {
-            // `storeUri`, not yet used
-            "",
-            // `systemTypes`
-            tokenizeString<StringSet>(tokens[1], ","),
-            // `sshKey`
-            tokens[2] == "-" ? "" : tokens[2],
-            // `maxJobs`
-            tokens[3] != ""
-                ? string2Int<MaxJobs>(tokens[3]).value()
-                : 1,
-            // `speedFactor`
-            std::stof(tokens[4].c_str()),
-            // `supportedFeatures`
-            std::move(supportedFeatures),
-            // `mandatoryFeatures`
-            std::move(mandatoryFeatures),
-            // `sshPublicHostKey`
-            tokens[7] != "" && tokens[7] != "-"
-                ? tokens[7]
-                : "",
-        });
-
-        machine->sshName = tokens[0];
+    for (auto && machine_ : nix::Machine::parseConfig({}, contents)) {
+        auto machine = std::make_shared<::Machine>(std::move(machine_));
 
         /* Re-use the State object of the previous machine with the
            same name. */
-        auto i = oldMachines.find(machine->sshName);
+        auto i = oldMachines.find(machine->storeUri.variant);
         if (i == oldMachines.end())
-            printMsg(lvlChatty, "adding new machine ‘%1%’", machine->sshName);
+            printMsg(lvlChatty, "adding new machine ‘%1%’", machine->storeUri.render());
         else
-            printMsg(lvlChatty, "updating machine ‘%1%’", machine->sshName);
+            printMsg(lvlChatty, "updating machine ‘%1%’", machine->storeUri.render());
         machine->state = i == oldMachines.end()
             ? std::make_shared<::Machine::State>()
             : i->second->state;
-        newMachines[machine->sshName] = machine;
+        newMachines[machine->storeUri.variant] = machine;
     }
 
     for (auto & m : oldMachines)
         if (newMachines.find(m.first) == newMachines.end()) {
             if (m.second->enabled)
-                printInfo("removing machine ‘%1%’", m.first);
+                printInfo("removing machine ‘%1%’", m.second->storeUri.render());
             /* Add a disabled ::Machine object to make sure stats are
                maintained. */
             auto machine = std::make_shared<::Machine>(*(m.second));
@@ -657,7 +618,7 @@ void State::dumpStatus(Connection & conn)
                     machine["avgStepTime"] = (float) s->totalStepTime / s->nrStepsDone;
                     machine["avgStepBuildTime"] = (float) s->totalStepBuildTime / s->nrStepsDone;
                 }
-                statusJson["machines"][m->sshName] = machine;
+                statusJson["machines"][m->storeUri.render()] = machine;
             }
         }
 

src/hydra-queue-runner/state.hh

@@ -6,7 +6,6 @@
 #include <map>
 #include <memory>
 #include <queue>
-#include <regex>
 
 #include <prometheus/counter.h>
 #include <prometheus/gauge.h>
@@ -241,10 +240,6 @@ struct Machine : nix::Machine
 {
     typedef std::shared_ptr<Machine> ptr;
 
-    /* TODO Get rid of: `nix::Machine::storeUri` is normalized in a way
-       we are not yet used to, but once we are, we don't need this. */
-    std::string sshName;
-
     struct State {
         typedef std::shared_ptr<State> ptr;
         counter currentJobs{0};
@@ -294,11 +289,7 @@ struct Machine : nix::Machine
         return true;
     }
 
-    bool isLocalhost()
-    {
-        std::regex r("^(ssh://|ssh-ng://)?localhost$");
-        return std::regex_search(sshName, r);
-    }
+    bool isLocalhost() const;
 
     // A connection to a machine
     struct Connection : nix::ServeProto::BasicClientConnection {
@@ -358,7 +349,7 @@ private:
 
     /* The build machines. */
     std::mutex machinesReadyLock;
-    typedef std::map<std::string, Machine::ptr> Machines;
+    typedef std::map<nix::StoreReference::Variant, Machine::ptr> Machines;
     nix::Sync<Machines> machines; // FIXME: use atomic_shared_ptr
 
     /* Various stats. */

src/lib/Hydra/Controller/Root.pm

@@ -51,6 +51,7 @@ sub begin :Private {
     $c->stash->{curUri} = $c->request->uri;
     $c->stash->{version} = $ENV{"HYDRA_RELEASE"} || "<devel>";
     $c->stash->{nixVersion} = $ENV{"NIX_RELEASE"} || "<devel>";
+    $c->stash->{nixEvalJobsVersion} = $ENV{"NIX_EVAL_JOBS_RELEASE"} || "<devel>";
     $c->stash->{curTime} = time;
     $c->stash->{logo} = defined $c->config->{hydra_logo} ? "/logo" : "";
     $c->stash->{tracker} = defined $c->config->{tracker} ? $c->config->{tracker} : "";

src/meson.build

@@ -1,6 +1,5 @@
 # Native code
 subdir('libhydra')
-subdir('hydra-eval-jobs')
 subdir('hydra-evaluator')
 subdir('hydra-queue-runner')
 

src/root/job.tt

@@ -27,15 +27,15 @@ removed or had an evaluation error.</div>
 <div id="generic-tabs" class="tab-content">
 
   <div id="tabs-status" class="tab-pane active">
-    [% IF queuedBuilds.size != 0 %]
-      <h3>Queued builds</h3>
-      [% INCLUDE renderBuildList builds=queuedBuilds showSchedulingInfo=1 hideResultInfo=1 %]
-    [% END %]
     [% IF lastBuilds.size != 0 %]
       <h3>Latest builds</h3>
       [% INCLUDE renderBuildList builds=lastBuilds
           linkToAll=c.uri_for('/job' project.name jobset.name job 'all') %]
     [% END %]
+    [% IF queuedBuilds.size != 0 %]
+      <h3>Queued builds</h3>
+      [% INCLUDE renderBuildList builds=queuedBuilds showSchedulingInfo=1 hideResultInfo=1 %]
+    [% END %]
   </div>
 
   [% IF constituentJobs.size > 0 %]

src/root/layout.tt

@@ -93,7 +93,7 @@
       <footer class="navbar">
         <hr />
         <small>
-          <em><a href="http://nixos.org/hydra" target="_blank" class="squiggle">Hydra</a> [% HTML.escape(version) %] (using [% HTML.escape(nixVersion) %]).</em>
+          <em><a href="http://nixos.org/hydra" target="_blank" class="squiggle">Hydra</a> [% HTML.escape(version) %] (using [% HTML.escape(nixVersion) %] and [% HTML.escape(nixEvalJobsVersion) %]).</em>
           [% IF c.user_exists %]
           You are signed in as <tt>[% HTML.escape(c.user.username) %]</tt>
             [%- IF c.user.type == 'google' %] via Google[% END %].

src/script/hydra-eval-jobset

@@ -17,6 +17,7 @@ use Hydra::Helper::Nix;
 use Hydra::Model::DB;
 use Hydra::Plugin;
 use Hydra::Schema;
+use IPC::Run;
 use JSON::MaybeXS;
 use Net::Statsd;
 use Nix::Store;
@@ -357,22 +358,32 @@ sub evalJobs {
     my @cmd;
 
     if (defined $flakeRef) {
-        @cmd = ("hydra-eval-jobs",
-                "--flake", $flakeRef,
-                "--gc-roots-dir", getGCRootsDir,
-                "--max-jobs", 1);
+        my $nix_expr =
+            "let " .
+            "flake = builtins.getFlake (toString \"$flakeRef\"); " .
+            "in " .
+            "flake.hydraJobs " .
+            "or flake.checks " .
+            "or (throw \"flake '$flakeRef' does not provide any Hydra jobs or checks\")";
+
+        @cmd = ("nix-eval-jobs", "--expr", $nix_expr);
     } 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 . "/" . $nixExprPath . ">",
-                "--gc-roots-dir", getGCRootsDir,
-                "--max-jobs", 1,
                 inputsToArgs($inputInfo));
     }
 
-    push @cmd, "--no-allow-import-from-derivation" if $config->{allow_import_from_derivation} // "true" ne "true";
+    push @cmd, ("--gc-roots-dir", getGCRootsDir);
+    push @cmd, ("--max-jobs", 1);
+    push @cmd, "--meta";
+    push @cmd, "--constituents";
+    push @cmd, "--force-recurse";
+    push @cmd, ("--option", "allow-import-from-derivation", "false") if $config->{allow_import_from_derivation} // "true" ne "true";
+    push @cmd, ("--workers", $config->{evaluator_workers} // 1);
+    push @cmd, ("--max-memory-size", $config->{evaluator_max_memory_size} // 4096);
 
     if (defined $ENV{'HYDRA_DEBUG'}) {
         sub escape {
@@ -384,14 +395,40 @@ 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))
-        . ":\n" . ($stderr ? decode("utf-8", $stderr) : "(no output)\n")
-        if $res;
+    my $evalProc = IPC::Run::start \@cmd,
+            '>', IPC::Run::new_chunker, \my $out,
+            '2>', \my $err;
 
-    print STDERR "$stderr";
+    return sub {
+        while (1) {
+            $evalProc->pump;
+            if (!defined $out && !defined $err) {
+                $evalProc->finish;
+                if ($?) {
+                    die "nix-eval-jobs returned " . ($? & 127 ? "signal $?" : "exit code " . ($? >> 8)) . "\n";
+                }
+                return;
+            }
 
-    return decode_json($jobsJSON);
+            if (defined $err) {
+                print STDERR "$err";
+                undef $err;
+            }
+
+            if (defined $out && $out ne '') {
+                my $job;
+                try {
+                    $job = decode_json($out);
+                } catch {
+                    warn "nix-eval-jobs sent invalid JSON.\n  parse error: $_\n  invalid json: $out\n";
+                };
+                undef $out;
+                if (defined $job) {
+                    return $job;
+                }
+            }
+        }
+    };
 }
 
 
@@ -420,7 +457,7 @@ 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 +511,30 @@ 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 +542,19 @@ 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 +723,7 @@ 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 +745,12 @@ 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 $evalStop = clock_gettime(CLOCK_MONOTONIC);
-
-    if ($jobsetsJobset) {
-        my @keys = keys %$jobs;
-        die "The .jobsets jobset must only have a single job named 'jobsets'"
-            unless (scalar @keys) == 1 && $keys[0] eq "jobsets";
-    }
-    Net::Statsd::timing("hydra.evaluator.eval_time", int(($evalStop - $evalStart) * 1000));
+    my $evalStop;
+    my $jobsIter = evalJobs($project->name . ":" . $jobset->name, $inputInfo, $jobset->nixexprinput, $jobset->nixexprpath, $flakeRef);
 
     if ($dryRun) {
-        foreach my $name (keys %{$jobs}) {
-            my $job = $jobs->{$name};
+        while (defined(my $job = $jobsIter->())) {
+            my $name = $job->{attr};
             if (defined $job->{drvPath}) {
                 print STDERR "good job $name: $job->{drvPath}\n";
             } else {
@@ -709,36 +760,23 @@ 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);
-
-
     # Store the error messages for jobs that failed to evaluate.
     my $evaluationErrorTime = time;
     my $evaluationErrorMsg = "";
-    foreach my $job (values %{$jobs}) {
-        next unless defined $job->{error};
-        $evaluationErrorMsg .=
-            ($job->{jobName} ne "" ? "in job ‘$job->{jobName}’" : "at top-level") .
-            ":\n" . $job->{error} . "\n\n";
-    }
-    setJobsetError($jobset, $evaluationErrorMsg, $evaluationErrorTime);
-
     my $evaluationErrorRecord = $db->resultset('EvaluationErrors')->create(
         { errormsg => $evaluationErrorMsg
         , errortime => $evaluationErrorTime
         }
     );
 
+    my $jobOutPathMap = {};
+    my $jobsetChanged = 0;
     my %buildMap;
-    $db->txn_do(sub {
 
+    my @jobs;
+    push @jobs, $_ while defined($_ = $jobsIter->());
+
+    $db->txn_do(sub {
         my $prevEval = getPrevJobsetEval($db, $jobset, 1);
 
         # Clear the "current" flag on all builds.  Since we're in a
@@ -751,7 +789,7 @@ sub checkJobsetWrapped {
             , evaluationerror => $evaluationErrorRecord
             , timestamp => time
             , checkouttime => abs(int($checkoutStop - $checkoutStart))
-            , evaltime => abs(int($evalStop - $evalStart))
+            , evaltime => 0
             , hasnewbuilds => 0
             , nrbuilds => 0
             , flake => $flakeRef
@@ -759,11 +797,24 @@ sub checkJobsetWrapped {
             , nixexprpath => $jobset->nixexprpath
             });
 
-        # Schedule each successfully evaluated job.
-        foreach my $job (permute(values %{$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);
+        my @jobsWithConstituents;
+
+        foreach my $job (@jobs) {
+            if ($jobsetsJobset) {
+                die "The .jobsets jobset must only have a single job named 'jobsets'"
+                    unless $job->{attr} eq "jobsets";
+            }
+
+            $evaluationErrorMsg .=
+                ($job->{attr} ne "" ? "in job ‘$job->{attr}’" : "at top-level") .
+                ":\n" . $job->{error} . "\n\n" if defined $job->{error};
+
+            checkBuild($db, $jobset, $ev, $inputInfo, $job, \%buildMap, $prevEval, $jobOutPathMap, $plugins)
+                unless defined $job->{error};
+
+            if (defined $job->{constituents}) {
+                push @jobsWithConstituents, $job;
+            }
         }
 
         # Have any builds been added or removed since last time?
@@ -801,21 +852,20 @@ sub checkJobsetWrapped {
                 $drvPathToId{$x->{drvPath}} = $x;
             }
 
-            foreach my $job (values %{$jobs}) {
-                next unless $job->{constituents};
-
+            foreach my $job (values @jobsWithConstituents) {
+                next unless defined $job->{constituents};
                 if (defined $job->{error}) {
-                    die "aggregate job ‘$job->{jobName}’ failed with the error: $job->{error}\n";
+                    die "aggregate job ‘$job->{attr}’ failed with the error: $job->{error}\n";
                 }
 
                 my $x = $drvPathToId{$job->{drvPath}} or
-                    die "aggregate job ‘$job->{jobName}’ has no corresponding build record.\n";
+                    die "aggregate job ‘$job->{attr}’ 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 ‘$drvPath’ that doesn't correspond to a Hydra build\n";
+                        warn "aggregate job ‘$job->{attr}’ has a constituent ‘$drvPath’ that doesn't correspond to a Hydra build\n";
                     }
                 }
             }
@@ -857,11 +907,15 @@ sub checkJobsetWrapped {
         $jobset->update({ enabled => 0 }) if $jobset->enabled == 2;
 
         $jobset->update({ lastcheckedtime => time, forceeval => undef });
+
+        $evaluationErrorRecord->update({ errormsg => $evaluationErrorMsg });
+        setJobsetError($jobset, $evaluationErrorMsg, $evaluationErrorTime);
+
+        $evalStop = clock_gettime(CLOCK_MONOTONIC);
+        $ev->update({ evaltime => abs(int($evalStop - $evalStart)) });
     });
 
-    my $dbStop = clock_gettime(CLOCK_MONOTONIC);
-
-    Net::Statsd::timing("hydra.evaluator.db_time", int(($dbStop - $dbStart) * 1000));
+    Net::Statsd::timing("hydra.evaluator.eval_time", int(($evalStop - $evalStart) * 1000));
     Net::Statsd::increment("hydra.evaluator.evals");
     Net::Statsd::increment("hydra.evaluator.cached_evals") unless $jobsetChanged;
 }

t/evaluator/evaluate-constituents-broken.t

@@ -18,14 +18,14 @@ 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/,
+    qr/aggregate job ‘mixed_aggregate’ failed with the error: "constituentA": does not exist/,
     "The stderr record includes a relevant error message"
 );
 
-$jobset->discard_changes;  # refresh from DB
+$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/,
+    qr/aggregate job ‘mixed_aggregate’ failed with the error: "constituentA": does not exist/,
     "The jobset records a relevant error message"
 );
 

t/evaluator/evaluate-constituents-gc.t

@@ -5,13 +5,58 @@ use Test2::V0;
 
 my $ctx = test_context();
 
-my $builds = $ctx->makeAndEvaluateJobset(
-    expression => 'constituents.nix',
+my $expression = 'constituents.nix';
+my $jobsetCtx = $ctx->makeJobset(
+    expression => $expression,
+);
+my $builds = $ctx->evaluateJobset(
+    jobset => $jobsetCtx->{"jobset"},
+    expression => $expression,
+    build => 0,
 );
 
 my $constituentA = $builds->{"constituentA"};
 my $directAggregate = $builds->{"direct_aggregate"};
 my $indirectAggregate = $builds->{"indirect_aggregate"};
+my $mixedAggregate = $builds->{"mixed_aggregate"};
+
+# Ensure that we get exactly the aggregates we expect
+my %expected_constituents = (
+    'direct_aggregate' => {
+        'constituentA' => 1,
+    },
+    'indirect_aggregate' => {
+        'constituentA' => 1,
+    },
+    'mixed_aggregate' => {
+        # Note that `constituentA_alias` becomes `constituentA`, because
+        # the shorter name is preferred
+        'constituentA' => 1,
+        'constituentB' => 1,
+    },
+);
+
+my $rs = $ctx->db->resultset('AggregateConstituents')->search(
+    {},
+    {
+        join     => [ 'aggregate', 'constituent' ],  # Use correct relationship names
+        columns  => [],
+        '+select' => [ 'aggregate.job', 'constituent.job' ],
+        '+as'     => [ 'aggregate_job', 'constituent_job' ],
+    }
+);
+
+my %actual_constituents;
+while (my $row = $rs->next) {
+    my $aggregate_job   = $row->get_column('aggregate_job');
+    my $constituent_job = $row->get_column('constituent_job');
+    $actual_constituents{$aggregate_job} //= {};
+    $actual_constituents{$aggregate_job}{$constituent_job} = 1;
+}
+
+is(\%actual_constituents, \%expected_constituents, "Exact aggregate constituents as expected");
+
+# Check that deletion also doesn't work accordingly
 
 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");

t/evaluator/evaluate-flake.t

@@ -0,0 +1,67 @@
+use feature 'unicode_strings';
+use strict;
+use warnings;
+use Setup;
+use Test2::V0;
+use File::Copy qw(cp);
+
+my $ctx = test_context(
+    nix_config => qq|
+    experimental-features = nix-command flakes
+    |,
+    hydra_config => q|
+    <runcommand>
+      evaluator_pure_eval = false
+    </runcommand>
+    |
+);
+
+sub checkFlake {
+    my ($flake) = @_;
+
+    cp($ctx->jobsdir . "/basic.nix", $ctx->jobsdir . "/" . $flake);
+    cp($ctx->jobsdir . "/config.nix", $ctx->jobsdir . "/" . $flake);
+    cp($ctx->jobsdir . "/empty-dir-builder.sh", $ctx->jobsdir . "/" . $flake);
+    cp($ctx->jobsdir . "/fail.sh", $ctx->jobsdir . "/" . $flake);
+    cp($ctx->jobsdir . "/succeed-with-failed.sh", $ctx->jobsdir . "/" . $flake);
+
+    chmod 0755, $ctx->jobsdir . "/" . $flake . "/empty-dir-builder.sh";
+    chmod 0755, $ctx->jobsdir . "/" . $flake . "/fail.sh";
+    chmod 0755, $ctx->jobsdir . "/" . $flake . "/succeed-with-failed.sh";
+
+    my $builds = $ctx->makeAndEvaluateJobset(
+        flake => 'path:' . $ctx->jobsdir . "/" . $flake,
+        build => 1
+    );
+
+    subtest "Build: succeed_with_failed" => sub {
+        my $build = $builds->{"succeed_with_failed"};
+
+        is($build->finished, 1, "Build should be finished.");
+        is($build->buildstatus, 6, "succeeeded-but-failed should have buildstatus 6.");
+    };
+
+    subtest "Build: empty_dir" => sub {
+        my $build = $builds->{"empty_dir"};
+
+        is($build->finished, 1, "Build should be finished.");
+        is($build->buildstatus, 0, "Should have succeeded.");
+    };
+
+    subtest "Build: fails" => sub {
+        my $build = $builds->{"fails"};
+
+        is($build->finished, 1, "Build should be finished.");
+        is($build->buildstatus, 1, "Should have failed.");
+    };
+}
+
+subtest "Flake using `checks`" => sub {
+    checkFlake 'flake-checks'
+};
+
+subtest "Flake using `hydraJobs`" => sub {
+    checkFlake 'flake-hydraJobs'
+};
+
+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/jobs/constituents.nix

@@ -5,6 +5,8 @@ rec {
     builder = ./empty-dir-builder.sh;
   };
 
+  constituentA_alias = constituentA;
+
   constituentB = mkDerivation {
     name = "empty-dir-B";
     builder = ./empty-dir-builder.sh;
@@ -32,7 +34,7 @@ rec {
     name = "mixed_aggregate";
     _hydraAggregate = true;
     constituents = [
-      "constituentA"
+      "constituentA_alias"
       constituentB
     ];
     builder = ./empty-dir-builder.sh;

t/jobs/flake-checks/flake.nix

@@ -0,0 +1,6 @@
+{
+  outputs = { ... }: {
+    checks =
+      import ./basic.nix;
+  };
+}

t/jobs/flake-hydraJobs/flake.nix

@@ -0,0 +1,6 @@
+{
+  outputs = { ... }: {
+    hydraJobs =
+      import ./basic.nix;
+  };
+}

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/lib/HydraTestContext.pm

@@ -165,20 +165,46 @@ sub nix_state_dir {
 sub makeAndEvaluateJobset {
     my ($self, %opts) = @_;
 
-    my $expression = $opts{'expression'} || die "Mandatory 'expression' option not passed to makeAndEvaluateJobset.\n";
-    my $jobsdir = $opts{'jobsdir'} // $self->jobsdir;
-    my $should_build = $opts{'build'} // 0;
+    my $expression = $opts{'expression'};
+    my $flake = $opts{'flake'};
+    if (not $expression and not $flake) {
+        die "One of 'expression' or 'flake' must be passed to makeEvaluateJobset.\n";
+    }
 
-    my $jobsetCtx = $self->makeJobset(
-        expression => $expression,
+    my $jobsdir = $opts{'jobsdir'} // $self->jobsdir;
+
+    my %args = (
         jobsdir => $jobsdir,
     );
-    my $jobset = $jobsetCtx->{"jobset"};
+    if ($expression) {
+        $args{expression} = $expression;
+    }
+    if ($flake) {
+        $args{flake} = $flake;
+    }
+    my $jobsetCtx = $self->makeJobset(%args);
+
+    return $self->evaluateJobset(
+        jobset => $jobsetCtx->{"jobset"},
+        expression => $expression,
+        flake => $flake,
+        build => $opts{"build"} // 0,
+    )
+}
+
+sub evaluateJobset {
+    my ($self, %opts) = @_;
+
+    my $jobset = $opts{'jobset'};
+
+    my $expression = $opts{'expression'} // $opts{'flake'};
 
     evalSucceeds($jobset) or die "Evaluating jobs/$expression should exit with return code 0.\n";
 
     my $builds = {};
 
+    my $should_build = $opts{'build'};
+
     for my $build ($jobset->builds) {
         if ($should_build) {
             runBuild($build) or die "Build '".$build->job."' from jobs/$expression should exit with return code 0.\n";
@@ -195,7 +221,7 @@ sub makeAndEvaluateJobset {
 #
 # In return, you get a hash of the user, project, and jobset records.
 #
-# This always uses an `expression` from the `jobsdir` directory.
+# This always uses an `expression` or `flake` from the `jobsdir` directory.
 #
 # Hash Parameters:
 #
@@ -204,7 +230,12 @@ sub makeAndEvaluateJobset {
 sub makeJobset {
     my ($self, %opts) = @_;
 
-    my $expression = $opts{'expression'} || die "Mandatory 'expression' option not passed to makeJobset.\n";
+    my $expression = $opts{'expression'};
+    my $flake = $opts{'flake'};
+    if (not $expression and not $flake) {
+        die "One of 'expression' or 'flake' must be passed to makeJobset.\n";
+    }
+
     my $jobsdir = $opts{'jobsdir'} // $self->jobsdir;
 
     # Create a new user for this test
@@ -222,12 +253,20 @@ sub makeJobset {
     });
 
     # Create a new jobset for this test and set up the inputs
-    my $jobset = $project->jobsets->create({
+    my %args = (
         name => rand_chars(),
-        nixexprinput => "jobs",
-        nixexprpath => $expression,
         emailoverride => ""
-    });
+    );
+    if ($expression) {
+        $args{type} = 0;
+        $args{nixexprinput} = "jobs";
+        $args{nixexprpath} = $expression;
+    }
+    if ($flake) {
+        $args{type} = 1;
+        $args{flake} = $flake;
+    }
+    my $jobset = $project->jobsets->create(\%args);
     my $jobsetinput = $jobset->jobsetinputs->create({name => "jobs", type => "path"});
     $jobsetinput->jobsetinputalts->create({altnr => 0, value => $jobsdir});
 

t/meson.build

@@ -27,7 +27,6 @@ testenv.prepend('PERL5LIB',
   separator: ':'
 )
 testenv.prepend('PATH',
-  fs.parent(hydra_eval_jobs.full_path()),
   fs.parent(hydra_evaluator.full_path()),
   fs.parent(hydra_queue_runner.full_path()),
   meson.project_source_root() / 'src/script',

t/queue-runner/constituents.t

@@ -22,11 +22,11 @@ is(nrQueuedBuildsForJobset($jobset), 0, "Evaluating jobs/broken-constituent.nix
 
 like(
     $jobset->errormsg,
-    qr/^does-not-exist: does not exist$/m,
+    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,
+    qr/^"does-not-evaluate": "error: assertion 'false' failed/m,
     "Evaluating jobs/broken-constituent.nix should log an error for does-not-evaluate");
 
 done_testing;