### Option `gc-keep-outputs' # # 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 = false ### Option `gc-keep-derivations' # # 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 safe a bit of disk space (or a lot if `gc-keep-outputs' is also # turned on). #gc-keep-derivations = true ### Option `env-keep-derivations' # # If `false' (default), derivations are not stored in Nix user # environments. That is, the derivation 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 `gc-keep-outputs'. # # The difference between this option and `gc-keep-derivations' is that # this one is `sticky': it applies to any user environment created # while this option was enabled, while `gc-keep-derivations' only # applies at the moment the garbage collector is run. #env-keep-derivations = false ### Option `build-max-jobs' # # This option defines the maximum number of jobs that Nix will try to # build in parallel. The default is 1. You should generally set it # to the number of CPUs in your system (e.g., 2 on a Athlon 64 X2). # It can be overriden using the `--max-jobs' / `-j' command line # switch. #build-max-jobs = 1 ### Option `build-cores' # # This option defines the number of CPU cores to utilize in parallel # within a build job, i.e. by passing an appropriate `-jN' flag to GNU # Make. The default is 1, meaning that parallel building within jobs # is disabled. Passing the special value `0' causes Nix to try and # auto-detect the number of available cores on the local host. This # setting can be overridden using the `--cores' command line switch. #build-cores = 1 ### Option `build-max-silent-time' # # 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 a 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 overriden using # the `--max-silent-time' command line switch. # # The value 0 means that there is no timeout. This is also the # default. # # Example: # build-max-silent-time = 600 # = 10 minutes #build-max-silent-time = 0 ### Option `build-users-group' # # 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', or the uid that owns the setuid nix-worker # program if $NIX_REMOTE is `slave'). Obviously, this should not be # used in multi-user settings with untrusted users. # # The default is empty. # # Example: # build-users-group = nix-builders #build-users-group = ### Option `build-use-chroot' # # If set to `true', builds will be performed in a chroot environment, # i.e., the build will be isolated from the normal file system # hierarchy and will only see the Nix store, the temporary build # directory, and the directories configured with the # `build-chroot-dirs' option (such as /proc and /dev). This is useful # to prevent undeclared dependencies on files in directories such as # /usr/bin. # # The use of a chroot requires that Nix is run as root (but you can # still use the "build users" feature to perform builds under # different users than root). Currently, chroot builds only work on # Linux because Nix uses "bind mounts" to make the Nix store and other # directories available inside the chroot. # # The default is `false'. # # Example: # build-use-chroot = true #build-use-chroot = false ### Option `build-chroot-dirs' # # When builds are performed in a chroot environment, Nix will mount # (using `mount --bind' on Linux) some directories from the normal # file system hierarchy inside the chroot. These are the Nix store, # the temporary build directory (usually /tmp/nix-<pid>-<number>) and # the directories listed here. The default is "/dev /dev/pts /proc". # Files in /dev (such as /dev/null) are needed by many builds, and # some files in /proc may also be needed occasionally. # # Example: # build-use-chroot = /dev /proc /bin #build-chroot-dirs = /dev /dev/pts /proc ### Option `build-cache-failure' # # If this option is enabled, Nix will do negative caching; that is, it # will remember failed builds, and won't attempt to try to build them # again if you ask for it. Negative caching is disabled by default # because Nix cannot distinguish between permanent build errors (e.g., # a syntax error in a source file) and transient build errors (e.g., a # full disk), as they both cause the builder to return a non-zero exit # code. You can clear the cache by doing `rm -f # /nix/var/nix/db/failed/*'. # # Example: # build-cache-failure = true #build-cache-failure = false