diff options
Diffstat (limited to 'src/libstore/globals.hh')
| -rw-r--r-- | src/libstore/globals.hh | 789 |
1 files changed, 649 insertions, 140 deletions
diff --git a/src/libstore/globals.hh b/src/libstore/globals.hh index e3bb4cf84..8a2d3ff75 100644 --- a/src/libstore/globals.hh +++ b/src/libstore/globals.hh @@ -80,89 +80,209 @@ public: Setting<bool> keepGoing{this, false, "keep-going", "Whether to keep building derivations when another build fails."}; - Setting<bool> tryFallback{this, false, "fallback", - "Whether to fall back to building when substitution fails.", + Setting<bool> tryFallback{ + this, false, "fallback", + R"( + If set to `true`, Nix will fall back to building from source if a + binary substitute fails. This is equivalent to the `--fallback` + flag. The default is `false`. + )", {"build-fallback"}}; /* Whether to show build log output in real time. */ bool verboseBuild = true; Setting<size_t> logLines{this, 10, "log-lines", - "If verbose-build is false, the number of lines of the tail of " + "If `verbose-build` is false, the number of lines of the tail of " "the log to show if a build fails."}; - MaxBuildJobsSetting maxBuildJobs{this, 1, "max-jobs", - "Maximum number of parallel build jobs. \"auto\" means use number of cores.", + MaxBuildJobsSetting maxBuildJobs{ + this, 1, "max-jobs", + R"( + This option defines the maximum number of jobs that Nix will try to + build in parallel. The default is `1`. The special value `auto` + causes Nix to use the number of CPUs in your system. `0` is useful + when using remote builders to prevent any local builds (except for + `preferLocalBuild` derivation attribute which executes locally + regardless). It can be overridden using the `--max-jobs` (`-j`) + command line switch. + )", {"build-max-jobs"}}; - Setting<unsigned int> buildCores{this, getDefaultCores(), "cores", - "Number of CPU cores to utilize in parallel within a build, " - "i.e. by passing this number to Make via '-j'. 0 means that the " - "number of actual CPU cores on the local host ought to be " - "auto-detected.", {"build-cores"}}; + Setting<unsigned int> buildCores{ + this, getDefaultCores(), "cores", + R"( + Sets the value of the `NIX_BUILD_CORES` environment variable in the + invocation of builders. Builders can use this variable at their + discretion to control the maximum amount of parallelism. For + instance, in Nixpkgs, if the derivation attribute + `enableParallelBuilding` is set to `true`, the builder passes the + `-jN` flag to GNU Make. It can be overridden using the `--cores` + command line switch and defaults to `1`. The value `0` means that + the builder should use all available CPU cores in the system. + )", + {"build-cores"}}; /* Read-only mode. Don't copy stuff to the store, don't change the database. */ bool readOnlyMode = false; - Setting<std::string> thisSystem{this, SYSTEM, "system", - "The canonical Nix system name."}; - - Setting<time_t> maxSilentTime{this, 0, "max-silent-time", - "The maximum time in seconds that a builer can go without " - "producing any output on stdout/stderr before it is killed. " - "0 means infinity.", + Setting<std::string> thisSystem{ + this, SYSTEM, "system", + R"( + This option specifies the canonical Nix system name of the current + installation, such as `i686-linux` or `x86_64-darwin`. Nix can only + build derivations whose `system` attribute equals the value + specified here. In general, it never makes sense to modify this + value from its default, since you can use it to ‘lie’ about the + platform you are building on (e.g., perform a Mac OS build on a + Linux machine; the result would obviously be wrong). It only makes + sense if the Nix binaries can run on multiple platforms, e.g., + ‘universal binaries’ that run on `x86_64-linux` and `i686-linux`. + + It defaults to the canonical Nix system name detected by `configure` + at build time. + )"}; + + Setting<time_t> maxSilentTime{ + this, 0, "max-silent-time", + R"( + This option defines the maximum number of seconds that a builder can + go without producing any data on standard output or standard error. + This is useful (for instance in an automated build system) to catch + builds that are stuck in an infinite loop, or to catch remote builds + that are hanging due to network problems. It can be overridden using + the `--max-silent-time` command line switch. + + The value `0` means that there is no timeout. This is also the + default. + )", {"build-max-silent-time"}}; - Setting<time_t> buildTimeout{this, 0, "timeout", - "The maximum duration in seconds that a builder can run. " - "0 means infinity.", {"build-timeout"}}; + Setting<time_t> buildTimeout{ + this, 0, "timeout", + R"( + This option defines the maximum number of seconds that a builder can + run. This is useful (for instance in an automated build system) to + catch builds that are stuck in an infinite loop but keep writing to + their standard output or standard error. It can be overridden using + the `--timeout` command line switch. + + The value `0` means that there is no timeout. This is also the + default. + )", + {"build-timeout"}}; PathSetting buildHook{this, true, nixLibexecDir + "/nix/build-remote", "build-hook", "The path of the helper program that executes builds to remote machines."}; - Setting<std::string> builders{this, "@" + nixConfDir + "/machines", "builders", - "A semicolon-separated list of build machines, in the format of nix.machines."}; - - Setting<bool> buildersUseSubstitutes{this, false, "builders-use-substitutes", - "Whether build machines should use their own substitutes for obtaining " - "build dependencies if possible, rather than waiting for this host to " - "upload them."}; + Setting<std::string> builders{ + this, "@" + nixConfDir + "/machines", "builders", + "A semicolon-separated list of build machines, in the format of `nix.machines`."}; + + Setting<bool> buildersUseSubstitutes{ + this, false, "builders-use-substitutes", + R"( + If set to `true`, Nix will instruct remote build machines to use + their own binary substitutes if available. In practical terms, this + means that remote hosts will fetch as many build dependencies as + possible from their own substitutes (e.g, from `cache.nixos.org`), + instead of waiting for this host to upload them all. This can + drastically reduce build times if the network connection between + this computer and the remote build host is slow. + )"}; Setting<off_t> reservedSize{this, 8 * 1024 * 1024, "gc-reserved-space", "Amount of reserved disk space for the garbage collector."}; - Setting<bool> fsyncMetadata{this, true, "fsync-metadata", - "Whether SQLite should use fsync()."}; + Setting<bool> fsyncMetadata{ + this, true, "fsync-metadata", + R"( + If set to `true`, changes to the Nix store metadata (in + `/nix/var/nix/db`) are synchronously flushed to disk. This improves + robustness in case of system crashes, but reduces performance. The + default is `true`. + )"}; Setting<bool> useSQLiteWAL{this, !isWSL1(), "use-sqlite-wal", "Whether SQLite should use WAL mode."}; Setting<bool> syncBeforeRegistering{this, false, "sync-before-registering", - "Whether to call sync() before registering a path as valid."}; - - Setting<bool> useSubstitutes{this, true, "substitute", - "Whether to use substitutes.", + "Whether to call `sync()` before registering a path as valid."}; + + Setting<bool> useSubstitutes{ + this, true, "substitute", + R"( + If set to `true` (default), Nix will use binary substitutes if + available. This option can be disabled to force building from + source. + )", {"build-use-substitutes"}}; - Setting<std::string> buildUsersGroup{this, "", "build-users-group", - "The Unix group that contains the build users."}; + Setting<std::string> buildUsersGroup{ + this, "", "build-users-group", + R"( + This options specifies the Unix group containing the Nix build user + accounts. In multi-user Nix installations, builds should not be + performed by the Nix account since that would allow users to + arbitrarily modify the Nix store and database by supplying specially + crafted builders; and they cannot be performed by the calling user + since that would allow him/her to influence the build result. + + Therefore, if this option is non-empty and specifies a valid group, + builds will be performed under the user accounts that are a member + of the group specified here (as listed in `/etc/group`). Those user + accounts should not be used for any other purpose\! + + Nix will never run two builds under the same user account at the + same time. This is to prevent an obvious security hole: a malicious + user writing a Nix expression that modifies the build result of a + legitimate Nix expression being built by another user. Therefore it + is good to have as many Nix build user accounts as you can spare. + (Remember: uids are cheap.) + + The build users should have permission to create files in the Nix + store, but not delete them. Therefore, `/nix/store` should be owned + by the Nix account, its group should be the group specified here, + and its mode should be `1775`. + + If the build users group is empty, builds will be performed under + the uid of the Nix process (that is, the uid of the caller if + `NIX_REMOTE` is empty, the uid under which the Nix daemon runs if + `NIX_REMOTE` is `daemon`). Obviously, this should not be used in + multi-user settings with untrusted users. + )"}; Setting<bool> impersonateLinux26{this, false, "impersonate-linux-26", "Whether to impersonate a Linux 2.6 machine on newer kernels.", {"build-impersonate-linux-26"}}; - Setting<bool> keepLog{this, true, "keep-build-log", - "Whether to store build logs.", + Setting<bool> keepLog{ + this, true, "keep-build-log", + R"( + If set to `true` (the default), Nix will write the build log of a + derivation (i.e. the standard output and error of its builder) to + the directory `/nix/var/log/nix/drvs`. The build log can be + retrieved using the command `nix-store -l path`. + )", {"build-keep-log"}}; - Setting<bool> compressLog{this, true, "compress-build-log", - "Whether to compress logs.", + Setting<bool> compressLog{ + this, true, "compress-build-log", + R"( + If set to `true` (the default), build logs written to + `/nix/var/log/nix/drvs` will be compressed on the fly using bzip2. + Otherwise, they will not be compressed. + )", {"build-compress-log"}}; - Setting<unsigned long> maxLogSize{this, 0, "max-build-log-size", - "Maximum number of bytes a builder can write to stdout/stderr " - "before being killed (0 means no limit).", + Setting<unsigned long> maxLogSize{ + this, 0, "max-build-log-size", + R"( + This option defines the maximum number of bytes that a builder can + write to its stdout/stderr. If the builder exceeds this limit, it’s + killed. A value of `0` (the default) means that there is no limit. + )", {"build-max-log-size"}}; /* When buildRepeat > 0 and verboseBuild == true, whether to print @@ -173,57 +293,156 @@ public: Setting<unsigned int> pollInterval{this, 5, "build-poll-interval", "How often (in seconds) to poll for locks."}; - Setting<bool> checkRootReachability{this, false, "gc-check-reachability", - "Whether to check if new GC roots can in fact be found by the " - "garbage collector."}; - - Setting<bool> gcKeepOutputs{this, false, "keep-outputs", - "Whether the garbage collector should keep outputs of live derivations.", + Setting<bool> gcKeepOutputs{ + this, false, "keep-outputs", + R"( + If `true`, the garbage collector will keep the outputs of + non-garbage derivations. If `false` (default), outputs will be + deleted unless they are GC roots themselves (or reachable from other + roots). + + In general, outputs must be registered as roots separately. However, + even if the output of a derivation is registered as a root, the + collector will still delete store paths that are used only at build + time (e.g., the C compiler, or source tarballs downloaded from the + network). To prevent it from doing so, set this option to `true`. + )", {"gc-keep-outputs"}}; - Setting<bool> gcKeepDerivations{this, true, "keep-derivations", - "Whether the garbage collector should keep derivers of live paths.", + Setting<bool> gcKeepDerivations{ + this, true, "keep-derivations", + R"( + If `true` (default), the garbage collector will keep the derivations + from which non-garbage store paths were built. If `false`, they will + be deleted unless explicitly registered as a root (or reachable from + other roots). + + Keeping derivation around is useful for querying and traceability + (e.g., it allows you to ask with what dependencies or options a + store path was built), so by default this option is on. Turn it off + to save a bit of disk space (or a lot if `keep-outputs` is also + turned on). + )", {"gc-keep-derivations"}}; - Setting<bool> autoOptimiseStore{this, false, "auto-optimise-store", - "Whether to automatically replace files with identical contents with hard links."}; - - Setting<bool> envKeepDerivations{this, false, "keep-env-derivations", - "Whether to add derivations as a dependency of user environments " - "(to prevent them from being GCed).", + Setting<bool> autoOptimiseStore{ + this, false, "auto-optimise-store", + R"( + If set to `true`, Nix automatically detects files in the store + that have identical contents, and replaces them with hard links to + a single copy. This saves disk space. If set to `false` (the + default), you can still run `nix-store --optimise` to get rid of + duplicate files. + )"}; + + Setting<bool> envKeepDerivations{ + this, false, "keep-env-derivations", + R"( + If `false` (default), derivations are not stored in Nix user + environments. That is, the derivations of any build-time-only + dependencies may be garbage-collected. + + If `true`, when you add a Nix derivation to a user environment, the + path of the derivation is stored in the user environment. Thus, the + derivation will not be garbage-collected until the user environment + generation is deleted (`nix-env --delete-generations`). To prevent + build-time-only dependencies from being collected, you should also + turn on `keep-outputs`. + + The difference between this option and `keep-derivations` is that + this one is “sticky”: it applies to any user environment created + while this option was enabled, while `keep-derivations` only applies + at the moment the garbage collector is run. + )", {"env-keep-derivations"}}; /* Whether to lock the Nix client and worker to the same CPU. */ bool lockCPU; - Setting<SandboxMode> sandboxMode{this, + Setting<SandboxMode> sandboxMode{ + this, #if __linux__ smEnabled #else smDisabled #endif , "sandbox", - "Whether to enable sandboxed builds. Can be \"true\", \"false\" or \"relaxed\".", + R"( + If set to `true`, builds will be performed in a *sandboxed + environment*, i.e., they’re isolated from the normal file system + hierarchy and will only see their dependencies in the Nix store, + the temporary build directory, private versions of `/proc`, + `/dev`, `/dev/shm` and `/dev/pts` (on Linux), and the paths + configured with the `sandbox-paths` option. This is useful to + prevent undeclared dependencies on files in directories such as + `/usr/bin`. In addition, on Linux, builds run in private PID, + mount, network, IPC and UTS namespaces to isolate them from other + processes in the system (except that fixed-output derivations do + not run in private network namespace to ensure they can access the + network). + + Currently, sandboxing only work on Linux and macOS. The use of a + sandbox requires that Nix is run as root (so you should use the + “build users” feature to perform the actual builds under different + users than root). + + If this option is set to `relaxed`, then fixed-output derivations + and derivations that have the `__noChroot` attribute set to `true` + do not run in sandboxes. + + The default is `true` on Linux and `false` on all other platforms. + )", {"build-use-chroot", "build-use-sandbox"}}; - Setting<PathSet> sandboxPaths{this, {}, "sandbox-paths", - "The paths to make available inside the build sandbox.", + Setting<PathSet> sandboxPaths{ + this, {}, "sandbox-paths", + R"( + A list of paths bind-mounted into Nix sandbox environments. You can + use the syntax `target=source` to mount a path in a different + location in the sandbox; for instance, `/bin=/nix-bin` will mount + the path `/nix-bin` as `/bin` inside the sandbox. If *source* is + followed by `?`, then it is not an error if *source* does not exist; + for example, `/dev/nvidiactl?` specifies that `/dev/nvidiactl` will + only be mounted in the sandbox if it exists in the host filesystem. + + Depending on how Nix was built, the default value for this option + may be empty or provide `/bin/sh` as a bind-mount of `bash`. + )", {"build-chroot-dirs", "build-sandbox-paths"}}; Setting<bool> sandboxFallback{this, true, "sandbox-fallback", "Whether to disable sandboxing when the kernel doesn't allow it."}; - Setting<PathSet> extraSandboxPaths{this, {}, "extra-sandbox-paths", - "Additional paths to make available inside the build sandbox.", + Setting<PathSet> extraSandboxPaths{ + this, {}, "extra-sandbox-paths", + R"( + A list of additional paths appended to `sandbox-paths`. Useful if + you want to extend its default value. + )", {"build-extra-chroot-dirs", "build-extra-sandbox-paths"}}; - Setting<size_t> buildRepeat{this, 0, "repeat", - "The number of times to repeat a build in order to verify determinism.", + Setting<size_t> buildRepeat{ + this, 0, "repeat", + R"( + How many times to repeat builds to check whether they are + deterministic. The default value is 0. If the value is non-zero, + every build is repeated the specified number of times. If the + contents of any of the runs differs from the previous ones and + `enforce-determinism` is true, the build is rejected and the + resulting store paths are not registered as “valid” in Nix’s + database. + )", {"build-repeat"}}; #if __linux__ - Setting<std::string> sandboxShmSize{this, "50%", "sandbox-dev-shm-size", - "The size of /dev/shm in the build sandbox."}; + Setting<std::string> sandboxShmSize{ + this, "50%", "sandbox-dev-shm-size", + R"( + This option determines the maximum size of the `tmpfs` filesystem + mounted on `/dev/shm` in Linux sandboxes. For the format, see the + description of the `size` option of `tmpfs` in mount8. The default + is `50%`. + )"}; Setting<Path> sandboxBuildDir{this, "/build", "sandbox-build-dir", "The build directory inside the sandbox."}; @@ -237,121 +456,411 @@ public: "Whether to log Darwin sandbox access violations to the system log."}; #endif - Setting<bool> runDiffHook{this, false, "run-diff-hook", - "Whether to run the program specified by the diff-hook setting " - "repeated builds produce a different result. Typically used to " - "plug in diffoscope."}; + Setting<bool> runDiffHook{ + this, false, "run-diff-hook", + R"( + If true, enable the execution of the `diff-hook` program. - PathSetting diffHook{this, true, "", "diff-hook", - "A program that prints out the differences between the two paths " - "specified on its command line."}; + When using the Nix daemon, `run-diff-hook` must be set in the + `nix.conf` configuration file, and cannot be passed at the command + line. + )"}; - Setting<bool> enforceDeterminism{this, true, "enforce-determinism", - "Whether to fail if repeated builds produce different output."}; + PathSetting diffHook{ + this, true, "", "diff-hook", + R"( + Absolute path to an executable capable of diffing build + results. The hook is executed if `run-diff-hook` is true, and the + output of a build is known to not be the same. This program is not + executed to determine if two results are the same. - Setting<Strings> trustedPublicKeys{this, - {"cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY="}, - "trusted-public-keys", - "Trusted public keys for secure substitution.", - {"binary-cache-public-keys"}}; + The diff hook is executed by the same user and group who ran the + build. However, the diff hook does not have write access to the + store path just built. + + The diff hook program receives three parameters: + + 1. A path to the previous build's results + + 2. A path to the current build's results - Setting<Strings> secretKeyFiles{this, {}, "secret-key-files", - "Secret keys with which to sign local builds."}; + 3. The path to the build's derivation - Setting<unsigned int> tarballTtl{this, 60 * 60, "tarball-ttl", - "How long downloaded files are considered up-to-date."}; + 4. The path to the build's scratch directory. This directory will + exist only if the build was run with `--keep-failed`. - Setting<bool> requireSigs{this, true, "require-sigs", - "Whether to check that any non-content-addressed path added to the " - "Nix store has a valid signature (that is, one signed using a key " - "listed in 'trusted-public-keys'."}; + The stderr and stdout output from the diff hook will not be + displayed to the user. Instead, it will print to the nix-daemon's + log. - Setting<StringSet> extraPlatforms{this, + When using the Nix daemon, `diff-hook` must be set in the `nix.conf` + configuration file, and cannot be passed at the command line. + )"}; + + Setting<bool> enforceDeterminism{ + this, true, "enforce-determinism", + "Whether to fail if repeated builds produce different output. See `repeat`."}; + + Setting<Strings> trustedPublicKeys{ + this, + {"cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY="}, + "trusted-public-keys", + R"( + A whitespace-separated list of public keys. When paths are copied + from another Nix store (such as a binary cache), they must be + signed with one of these keys. For example: + `cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= + hydra.nixos.org-1:CNHJZBh9K4tP3EKF6FkkgeVYsS3ohTl+oS0Qa8bezVs=`. + )", + {"binary-cache-public-keys"}}; + + Setting<Strings> secretKeyFiles{ + this, {}, "secret-key-files", + R"( + A whitespace-separated list of files containing secret (private) + keys. These are used to sign locally-built paths. They can be + generated using `nix-store --generate-binary-cache-key`. The + corresponding public key can be distributed to other users, who + can add it to `trusted-public-keys` in their `nix.conf`. + )"}; + + Setting<unsigned int> tarballTtl{ + this, 60 * 60, "tarball-ttl", + R"( + The number of seconds a downloaded tarball is considered fresh. If + the cached tarball is stale, Nix will check whether it is still up + to date using the ETag header. Nix will download a new version if + the ETag header is unsupported, or the cached ETag doesn't match. + + Setting the TTL to `0` forces Nix to always check if the tarball is + up to date. + + Nix caches tarballs in `$XDG_CACHE_HOME/nix/tarballs`. + + Files fetched via `NIX_PATH`, `fetchGit`, `fetchMercurial`, + `fetchTarball`, and `fetchurl` respect this TTL. + )"}; + + Setting<bool> requireSigs{ + this, true, "require-sigs", + R"( + If set to `true` (the default), any non-content-addressed path added + or copied to the Nix store (e.g. when substituting from a binary + cache) must have a valid signature, that is, be signed using one of + the keys listed in `trusted-public-keys` or `secret-key-files`. Set + to `false` to disable signature checking. + )"}; + + Setting<StringSet> extraPlatforms{ + this, std::string{SYSTEM} == "x86_64-linux" && !isWSL1() ? StringSet{"i686-linux"} : StringSet{}, "extra-platforms", - "Additional platforms that can be built on the local system. " - "These may be supported natively (e.g. armv7 on some aarch64 CPUs " - "or using hacks like qemu-user."}; - - Setting<StringSet> systemFeatures{this, getDefaultSystemFeatures(), + R"( + Platforms other than the native one which this machine is capable of + building for. This can be useful for supporting additional + architectures on compatible machines: i686-linux can be built on + x86\_64-linux machines (and the default for this setting reflects + this); armv7 is backwards-compatible with armv6 and armv5tel; some + aarch64 machines can also natively run 32-bit ARM code; and + qemu-user may be used to support non-native platforms (though this + may be slow and buggy). Most values for this are not enabled by + default because build systems will often misdetect the target + platform and generate incompatible code, so you may wish to + cross-check the results of using this option against proper + natively-built versions of your derivations. + )"}; + + Setting<StringSet> systemFeatures{ + this, getDefaultSystemFeatures(), "system-features", - "Optional features that this system implements (like \"kvm\")."}; + R"( + A set of system “features” supported by this machine, e.g. `kvm`. + Derivations can express a dependency on such features through the + derivation attribute `requiredSystemFeatures`. For example, the + attribute + + requiredSystemFeatures = [ "kvm" ]; + + ensures that the derivation can only be built on a machine with the + `kvm` feature. - Setting<Strings> substituters{this, + This setting by default includes `kvm` if `/dev/kvm` is accessible, + and the pseudo-features `nixos-test`, `benchmark` and `big-parallel` + that are used in Nixpkgs to route builds to specific machines. + )"}; + + Setting<Strings> substituters{ + this, nixStore == "/nix/store" ? Strings{"https://cache.nixos.org/"} : Strings(), "substituters", - "The URIs of substituters (such as https://cache.nixos.org/).", + R"( + A list of URLs of substituters, separated by whitespace. The default + is `https://cache.nixos.org`. + )", {"binary-caches"}}; // FIXME: provide a way to add to option values. - Setting<Strings> extraSubstituters{this, {}, "extra-substituters", - "Additional URIs of substituters.", + Setting<Strings> extraSubstituters{ + this, {}, "extra-substituters", + R"( + Additional binary caches appended to those specified in + `substituters`. When used by unprivileged users, untrusted + substituters (i.e. those not listed in `trusted-substituters`) are + silently ignored. + )", {"extra-binary-caches"}}; - Setting<StringSet> trustedSubstituters{this, {}, "trusted-substituters", - "Disabled substituters that may be enabled via the substituters option by untrusted users.", + Setting<StringSet> trustedSubstituters{ + this, {}, "trusted-substituters", + R"( + A list of URLs of substituters, separated by whitespace. These are + not used by default, but can be enabled by users of the Nix daemon + by specifying `--option substituters urls` on the command + line. Unprivileged users are only allowed to pass a subset of the + URLs listed in `substituters` and `trusted-substituters`. + )", {"trusted-binary-caches"}}; - Setting<Strings> trustedUsers{this, {"root"}, "trusted-users", - "Which users or groups are trusted to ask the daemon to do unsafe things."}; - - Setting<unsigned int> ttlNegativeNarInfoCache{this, 3600, "narinfo-cache-negative-ttl", - "The TTL in seconds for negative lookups in the disk cache i.e binary cache lookups that " - "return an invalid path result"}; - - Setting<unsigned int> ttlPositiveNarInfoCache{this, 30 * 24 * 3600, "narinfo-cache-positive-ttl", - "The TTL in seconds for positive lookups in the disk cache i.e binary cache lookups that " - "return a valid path result."}; + Setting<Strings> trustedUsers{ + this, {"root"}, "trusted-users", + R"( + A list of names of users (separated by whitespace) that have + additional rights when connecting to the Nix daemon, such as the + ability to specify additional binary caches, or to import unsigned + NARs. You can also specify groups by prefixing them with `@`; for + instance, `@wheel` means all users in the `wheel` group. The default + is `root`. + + > **Warning** + > + > Adding a user to `trusted-users` is essentially equivalent to + > giving that user root access to the system. For example, the user + > can set `sandbox-paths` and thereby obtain read access to + > directories that are otherwise inacessible to them. + )"}; + + Setting<unsigned int> ttlNegativeNarInfoCache{ + this, 3600, "narinfo-cache-negative-ttl", + R"( + The TTL in seconds for negative lookups. If a store path is queried + from a substituter but was not found, there will be a negative + lookup cached in the local disk cache database for the specified + duration. + )"}; + + Setting<unsigned int> ttlPositiveNarInfoCache{ + this, 30 * 24 * 3600, "narinfo-cache-positive-ttl", + R"( + The TTL in seconds for positive lookups. If a store path is queried + from a substituter, the result of the query will be cached in the + local disk cache database including some of the NAR metadata. The + default TTL is a month, setting a shorter TTL for positive lookups + can be useful for binary caches that have frequent garbage + collection, in which case having a more frequent cache invalidation + would prevent trying to pull the path again and failing with a hash + mismatch if the build isn't reproducible. + )"}; /* ?Who we trust to use the daemon in safe ways */ - Setting<Strings> allowedUsers{this, {"*"}, "allowed-users", - "Which users or groups are allowed to connect to the daemon."}; + Setting<Strings> allowedUsers{ + this, {"*"}, "allowed-users", + R"( + A list of names of users (separated by whitespace) that are allowed + to connect to the Nix daemon. As with the `trusted-users` option, + you can specify groups by prefixing them with `@`. Also, you can + allow all users by specifying `*`. The default is `*`. + + Note that trusted users are always allowed to connect. + )"}; Setting<bool> printMissing{this, true, "print-missing", "Whether to print what paths need to be built or downloaded."}; - Setting<std::string> preBuildHook{this, "", - "pre-build-hook", - "A program to run just before a build to set derivation-specific build settings."}; + Setting<std::string> preBuildHook{ + this, "", "pre-build-hook", + R"( + If set, the path to a program that can set extra derivation-specific + settings for this system. This is used for settings that can't be + captured by the derivation model itself and are too variable between + different versions of the same system to be hard-coded into nix. + + The hook is passed the derivation path and, if sandboxes are + enabled, the sandbox directory. It can then modify the sandbox and + send a series of commands to modify various settings to stdout. The + currently recognized commands are: + + - `extra-sandbox-paths` + Pass a list of files and directories to be included in the + sandbox for this build. One entry per line, terminated by an + empty line. Entries have the same format as `sandbox-paths`. + )"}; + + Setting<std::string> postBuildHook{ + this, "", "post-build-hook", + R"( + Optional. The path to a program to execute after each build. + + This option is only settable in the global `nix.conf`, or on the + command line by trusted users. + + When using the nix-daemon, the daemon executes the hook as `root`. + If the nix-daemon is not involved, the hook runs as the user + executing the nix-build. + + - The hook executes after an evaluation-time build. + + - The hook does not execute on substituted paths. + + - The hook's output always goes to the user's terminal. + + - If the hook fails, the build succeeds but no further builds + execute. - Setting<std::string> postBuildHook{this, "", "post-build-hook", - "A program to run just after each successful build."}; + - The hook executes synchronously, and blocks other builds from + progressing while it runs. - Setting<std::string> netrcFile{this, fmt("%s/%s", nixConfDir, "netrc"), "netrc-file", - "Path to the netrc file used to obtain usernames/passwords for downloads."}; + The program executes with no arguments. The program's environment + contains the following environment variables: + + - `DRV_PATH` + The derivation for the built paths. + + Example: + `/nix/store/5nihn1a7pa8b25l9zafqaqibznlvvp3f-bash-4.4-p23.drv` + + - `OUT_PATHS` + Output paths of the built derivation, separated by a space + character. + + Example: + `/nix/store/zf5lbh336mnzf1nlswdn11g4n2m8zh3g-bash-4.4-p23-dev + /nix/store/rjxwxwv1fpn9wa2x5ssk5phzwlcv4mna-bash-4.4-p23-doc + /nix/store/6bqvbzjkcp9695dq0dpl5y43nvy37pq1-bash-4.4-p23-info + /nix/store/r7fng3kk3vlpdlh2idnrbn37vh4imlj2-bash-4.4-p23-man + /nix/store/xfghy8ixrhz3kyy6p724iv3cxji088dx-bash-4.4-p23`. + )"}; + + Setting<std::string> netrcFile{ + this, fmt("%s/%s", nixConfDir, "netrc"), "netrc-file", + R"( + If set to an absolute path to a `netrc` file, Nix will use the HTTP + authentication credentials in this file when trying to download from + a remote host through HTTP or HTTPS. Defaults to + `$NIX_CONF_DIR/netrc`. + + The `netrc` file consists of a list of accounts in the following + format: + + machine my-machine + login my-username + password my-password + + For the exact syntax, see [the `curl` + documentation](https://ec.haxx.se/usingcurl-netrc.html). + + > **Note** + > + > This must be an absolute path, and `~` is not resolved. For + > example, `~/.netrc` won't resolve to your home directory's + > `.netrc`. + )"}; /* Path to the SSL CA file used */ Path caFile; #if __linux__ - Setting<bool> filterSyscalls{this, true, "filter-syscalls", - "Whether to prevent certain dangerous system calls, such as " - "creation of setuid/setgid files or adding ACLs or extended " - "attributes. Only disable this if you're aware of the " - "security implications."}; - - Setting<bool> allowNewPrivileges{this, false, "allow-new-privileges", - "Whether builders can acquire new privileges by calling programs with " - "setuid/setgid bits or with file capabilities."}; + Setting<bool> filterSyscalls{ + this, true, "filter-syscalls", + R"( + Whether to prevent certain dangerous system calls, such as + creation of setuid/setgid files or adding ACLs or extended + attributes. Only disable this if you're aware of the + security implications. + )"}; + + Setting<bool> allowNewPrivileges{ + this, false, "allow-new-privileges", + R"( + (Linux-specific.) By default, builders on Linux cannot acquire new + privileges by calling setuid/setgid programs or programs that have + file capabilities. For example, programs such as `sudo` or `ping` + will fail. (Note that in sandbox builds, no such programs are + available unless you bind-mount them into the sandbox via the + `sandbox-paths` option.) You can allow the use of such programs by + enabling this option. This is impure and usually undesirable, but + may be useful in certain scenarios (e.g. to spin up containers or + set up userspace network interfaces in tests). + )"}; #endif - Setting<Strings> hashedMirrors{this, {}, "hashed-mirrors", - "A list of servers used by builtins.fetchurl to fetch files by hash."}; - - Setting<uint64_t> minFree{this, 0, "min-free", - "Automatically run the garbage collector when free disk space drops below the specified amount."}; - - Setting<uint64_t> maxFree{this, std::numeric_limits<uint64_t>::max(), "max-free", - "Stop deleting garbage when free disk space is above the specified amount."}; + Setting<Strings> hashedMirrors{ + this, {}, "hashed-mirrors", + R"( + A list of web servers used by `builtins.fetchurl` to obtain files by + hash. The default is `http://tarballs.nixos.org/`. Given a hash type + *ht* and a base-16 hash *h*, Nix will try to download the file from + *hashed-mirror*/*ht*/*h*. This allows files to be downloaded even if + they have disappeared from their original URI. For example, given + the default mirror `http://tarballs.nixos.org/`, when building the + derivation + + ```nix + builtins.fetchurl { + url = "https://example.org/foo-1.2.3.tar.xz"; + sha256 = "2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae"; + } + ``` + + Nix will attempt to download this file from + `http://tarballs.nixos.org/sha256/2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae` + first. If it is not available there, if will try the original URI. + )"}; + + Setting<uint64_t> minFree{ + this, 0, "min-free", + R"( + When free disk space in `/nix/store` drops below `min-free` during a + build, Nix performs a garbage-collection until `max-free` bytes are + available or there is no more garbage. A value of `0` (the default) + disables this feature. + )"}; + + Setting<uint64_t> maxFree{ + this, std::numeric_limits<uint64_t>::max(), "max-free", + R"( + When a garbage collection is triggered by the `min-free` option, it + stops as soon as `max-free` bytes are available. The default is + infinity (i.e. delete all garbage). + )"}; Setting<uint64_t> minFreeCheckInterval{this, 5, "min-free-check-interval", "Number of seconds between checking free disk space."}; - Setting<Paths> pluginFiles{this, {}, "plugin-files", - "Plugins to dynamically load at nix initialization time."}; + Setting<Paths> pluginFiles{ + this, {}, "plugin-files", + R"( + A list of plugin files to be loaded by Nix. Each of these files will + be dlopened by Nix, allowing them to affect execution through static + initialization. In particular, these plugins may construct static + instances of RegisterPrimOp to add new primops or constants to the + expression language, RegisterStoreImplementation to add new store + implementations, RegisterCommand to add new subcommands to the `nix` + command, and RegisterSetting to add new nix config settings. See the + constructors for those types for more details. + + Since these files are loaded into the same address space as Nix + itself, they must be DSOs compatible with the instance of Nix + running at the time (i.e. compiled against the same headers, not + linked to any incompatible libraries). They should not be linked to + any Nix libs directly, as those will be available already at load + time. + + If an entry in the list is a directory, all files in the directory + are loaded as plugins (non-recursively). + )"}; Setting<std::string> githubAccessToken{this, "", "github-access-token", - "GitHub access token to get access to GitHub data through the GitHub API for github:<..> flakes."}; + "GitHub access token to get access to GitHub data through the GitHub API for `github:<..>` flakes."}; Setting<Strings> experimentalFeatures{this, {}, "experimental-features", "Experimental Nix features to enable."}; |