You can now include files via the "builders" option, using the syntax
"@<filename>". Having only one option makes it easier to override
builders completely.
For backward compatibility, the default is "@/etc/nix/machines", or
"@<filename>" for each file name in NIX_REMOTE_SYSTEMS.
This makes it slightly more manageable to see at a glance what in a
build's sandbox profile is unique to the build and what is standard. Also
a first step to factoring more of our Darwin logic into scheme functions
that will allow us a bit more flexibility. And of course less of that
nasty codegen in C++! 😀
This speeds up commands like "nix cat-store". For example:
$ time nix cat-store --store https://cache.nixos.org?local-nar-cache=/tmp/nar-cache /nix/store/i60yncmq6w9dyv37zd2k454g0fkl3arl-systemd-234/etc/udev/udev.conf
real 0m4.336s
$ time nix cat-store --store https://cache.nixos.org?local-nar-cache=/tmp/nar-cache /nix/store/i60yncmq6w9dyv37zd2k454g0fkl3arl-systemd-234/etc/udev/udev.conf
real 0m0.045s
The primary motivation is to allow hydra-server to serve files from S3
binary caches. Previously Hydra had a hack to do "nix-store -r
<path>", but that fetches the entire closure so is prohibitively
expensive.
There is no garbage collection of the NAR cache yet. Also, the entire
NAR is read when accessing a single member file. We could generate the
NAR listing to provide random access.
Note: the NAR cache is indexed by the store path hash, not the content
hash, so NAR caches should not be shared between binary caches, unless
you're sure that all your builds are binary-reproducible.
Probably as a result of a bad merge in
4b8f1b0ec0, we had both a
BinaryCacheStoreAccessor and a
RemoteFSAccessor. BinaryCacheStore::getFSAccessor() returned the
latter, but BinaryCacheStore::addToStore() checked for the
former. This probably caused hydra-queue-runner to download paths that
it just uploaded.
This check spuriously fails for e.g. git@github.com:NixOS/nixpkgs.git,
and even for ssh://git@github.com/NixOS/nixpkgs.git, and is made
redundant by the checks git itself will do when fetching the repo. We
instead pass a -- before passing the URI to git to avoid injection.
I needed this to test ACL/xattr removal in
canonicalisePathMetaData(). Might also be useful if you need to build
old Nixpkgs that doesn't have the required patches to remove
setuid/setgid creation.
The worker threads could exit prematurely if they finished processing
all items while the main thread was still adding items. In particular,
this caused hanging nix-store --serve processes in the build farm.
Also, process items from the main thread.
It was getting too much like whac-a-mole listing all the retriable error
conditions, so we now retry by default and list the cases where retrying
is almost certainly hopeless.
I find the error message 'nix-env --set-flag priority NUMBER PKGNAME'
not as helpful as it could be :
- doesn't share the current priorities
- doesn't say that the command must be run on the already installed
PKGNAME (which is confusing the first time)
- the doc needs careful reading:
"If there are multiple derivations matching a name in args that have the same name (e.g., gcc-3.3.6 and gcc-4.1.1), then the derivation with the highest priority is used."
if one stops reading there, he is screwed. Salvation comes with reading "A derivation can define a priority by declaring the meta.priority attribute. This attribute should be a number, with a higher value denoting a lower priority. The default priority is 0."
To sum it up, lower number wins. I tried to convey this idea in the
message too.
This is a hack to make hydra-queue-runner free its temproots
periodically, thereby ensuring that garbage collection of the
corresponding paths is not blocked until the queue runner is
restarted.
It would be better if temproots could be released earlier than at
process exit. I started working on a RAII object returned by functions
like addToStore() that releases temproots. However, this would be a
pretty massive change so I gave up on it for now.
For example,
$ nix-store -q --roots /nix/store/7phd2sav7068nivgvmj2vpm3v47fd27l-patchelf-0.8pre845_0315148
{temp:1}
denotes that the path is only being kept alive by a temporary root
(i.e. /nix/var/nix/temproots/). Similarly,
$ nix-store --gc --print-roots
...
{memory:9} -> /nix/store/094gpjn9f15ip17wzxhma4r51nvsj17p-curl-7.53.1
shows that curl is being used by some process.
This command shows why a package has another package in its runtime
closure. For example, to see why VLC has libdrm.dev in its closure:
$ nix why-depends nixpkgs.vlc nixpkgs.libdrm.dev
/nix/store/g901z9pcj0n5yy5n6ykxk3qm4ina1d6z-vlc-2.2.5.1:
lib/libvlccore.so.8.0.0: …nfig:/nix/store/405lmx6jl8lp0ad1vrr6j498chrqhz8g-libdrm-2.4.75-d…
/nix/store/s3nm7kd8hlcg0facn2q1ff2n7wrwdi2l-mesa-noglu-17.0.7-dev:
nix-support/propagated-native-build-inputs: …-dev /nix/store/405lmx6jl8lp0ad1vrr6j498chrqhz8g-libdrm-2.4.75-d…
Thus, VLC's lib/libvlccore.so.8.0.0 as well as mesa-noglu's
nix-support/propagated-native-build-inputs cause the dependency.
In particular, process() won't return as long as there are active
items. This prevents work item lambdas from referring to stack frames
that no longer exist.
Since we may use a dedicated file descriptor in the future, this
allows us to change it. So builders can do
if [[ -n $NIX_LOG_FD ]]; then
echo "@nix { message... }" >&$NIX_LOG_FD
fi
Nix can now automatically run the garbage collector during builds or
while adding paths to the store. The option "min-free = <bytes>"
specifies that Nix should run the garbage collector whenever free
space in the Nix store drops below <bytes>. It will then delete
garbage until "max-free" bytes are available.
Garbage collection during builds is asynchronous; running builds are
not paused and new builds are not blocked. However, there also is a
synchronous GC run prior to the first build/substitution.
Currently, no old GC roots are deleted (as in "nix-collect-garbage
-d").
Since file locks are per-process rather than per-file-descriptor, the
garbage collector would always acquire a lock on its own temproots
file and conclude that it's stale.
Without this, substitute info is fetched sequentially, which is
superslow. In the old UI (e.g. nix-build), we call printMissing(),
which calls queryMissing(), thereby preheating the binary cache
cache. But the new UI doesn't do that.
In particular, drop the "build-" and "gc-" prefixes which are
pointless. So now you can say
nix build --no-sandbox
instead of
nix build --no-build-use-sandbox
This is useful for testing commands in isolation.
For example,
$ nix run nixpkgs.geeqie -i -k DISPLAY -k XAUTHORITY -c geeqie
runs geeqie in an empty environment, except for $DISPLAY and
$XAUTHORITY.
E.g.
nix run nixpkgs.hello -c hello --greeting Hallo
Note that unlike "nix-shell --command", no quoting of arguments is
necessary.
"-c" (short for "--command") cannot be combined with "--" because they
both consume all remaining arguments. But since installables shouldn't
start with a dash, this is unlikely to cause problems.
Running "nix run" with a diverted store, e.g.
$ nix run --store local?root=/tmp/nix nixpkgs.hello
stopped working when Nix became multithreaded, because
unshare(CLONE_NEWUSER) doesn't work in multithreaded processes. The
obvious solution is to terminate all other threads first, but 1) there
is no way to terminate Boehm GC marker threads; and 2) it appears that
the kernel has a race where unshare(CLONE_NEWUSER) will still fail for
some indeterminate amount of time after joining other threads.
So instead, "nix run" will now exec() a single-threaded helper ("nix
__run_in_chroot") that performs the actual unshare()/chroot()/exec().
Now that we use threads in lots of places, it's possible for
TunnelLogger::log() to be called asynchronously from other threads
than the main loop. So we need to ensure that STDERR_NEXT messages
don't clobber other messages.
