RewritingSink can handle being fed input where a reference crosses a
chunk boundary. we don't need to load the whole source into memory, and
in fact *not* loading the whole source lets nix build FODs that do not
fit into memory (eg fetchurl'ing data files larger than system memory).
Once a derivation goal has been completed, we check whether or not
this goal was meant to be repeated to check its output.
An early return branch was preventing the worker to reach that repeat
code branch, hence breaking the --check command (#2619).
It seems like this early return branch is an artifact of a passed
refactoring. As far as I can tell, buildDone's main branch also
cleanup the tmp directory before returning.
By default, Nix sets the "cores" setting to the number of CPUs which are
physically present on the machine. If cgroups are used to limit the CPU
and memory consumption of a large Nix build, the OOM killer may be
invoked.
For example, consider a GitLab CI pipeline which builds a large software
package. The GitLab runner spawns a container whose CPU is limited to 4
cores and whose memory is limited to 16 GiB. If the underlying machine
has 64 cores, Nix will invoke the build with -j64. In many cases, that
level of parallelism will invoke the OOM killer and the build will
completely fail.
This change sets the default value of "cores" to be
ceil(cpu_quota / cpu_period), with a fallback to
std:🧵:hardware_concurrency() if cgroups v2 is not detected.
The workaround for "Some distros patch Linux" mentioned in
local-derivation-goal.cc will not help in the `--option
sandbox-fallback false` case. To provide the user more helpful
guidance on how to get the sandbox working, let's check to see if the
`/proc` node created by the aforementioned patch is present and
configured in a way that will cause us problems. If so, give the user
a suggestion for how to troubleshoot the problem.
local-derivation-goal.cc contains a comment stating that "Some distros
patch Linux to not allow unprivileged user namespaces." Let's give a
pointer to a common version of this patch for those who want more
details about this failure mode.
This commit causes nix to `warn()` if sandbox setup has failed and
`/proc/self/ns/user` does not exist. This is usually a sign that the
kernel was compiled without `CONFIG_USER_NS=y`, which is required for
sandboxing.
This commit uses `warn()` to notify the user if sandbox setup fails
with errno==EPERM and /proc/sys/user/max_user_namespaces is missing or
zero, since that is at least part of the reason why sandbox setup
failed.
Note that `echo -n 0 > /proc/sys/user/max_user_namespaces` or
equivalent at boot time has been the recommended mitigation for
several Linux LPE vulnerabilities over the past few years. Many users
have applied this mitigation and then forgotten that they have done
so.
The failure modes for nix's sandboxing setup are pretty complicated.
When nix is unable to set up the sandbox, let's provide more detail
about what went wrong. Specifically:
* Make sure the error message includes the word "sandbox" so the user
knows that the failure was related to sandboxing.
* If `--option sandbox-fallback false` was provided, and removing it
would have allowed further attempts to make progress, let the user
know.
Specifically, if we're not root and the daemon socket does not exist,
then we use ~/.local/share/nix/root as a chroot store. This enables
non-root users to download nix-static and have it work out of the box,
e.g.
ubuntu@ip-10-13-1-146:~$ ~/nix run nixpkgs#hello
warning: '/nix' does not exists, so Nix will use '/home/ubuntu/.local/share/nix/root' as a chroot store
Hello, world!
With this, Nix will write a copy of the sandbox shell to /bin/sh in
the sandbox rather than bind-mounting it from the host filesystem.
This makes /bin/sh work out of the box with nix-static, i.e. you no
longer get
/nix/store/qa36xhc5gpf42l3z1a8m1lysi40l9p7s-bootstrap-stage4-stdenv-linux/setup: ./configure: /bin/sh: bad interpreter: No such file or directory
This allows changes to nix-cache-info to be picked up by existing
clients. Previously, the only way for this to happen would be for
clients to delete binary-cache-v6.sqlite, which is quite awkward for
users.
On the other hand, updates to nix-cache-info should be pretty rare,
hence the choice of a fairly long TTL. Configurability is probably not
useful enough to warrant implementing it.
The manpage for `getgrouplist` says:
> If the number of groups of which user is a member is less than or
> equal to *ngroups, then the value *ngroups is returned.
>
> If the user is a member of more than *ngroups groups, then
> getgrouplist() returns -1. In this case, the value returned in
> *ngroups can be used to resize the buffer passed to a further
> call getgrouplist().
In our original code, however, we allocated a list of size `10` and, if
`getgrouplist` returned `-1` threw an exception. In practice, this
caused the code to fail for any user belonging to more than 10 groups.
While unusual for single-user systems, large companies commonly have a
huge number of POSIX groups users belong to, causing this issue to crop
up and make multi-user Nix unusable in such settings.
The fix is relatively simple, when `getgrouplist` fails, it stores the
real number of GIDs in `ngroups`, so we must resize our list and retry.
Only then, if it errors once more, we can raise an exception.
This should be backported to, at least, 2.9.x.
Bring back the possibility to copy CA paths with no reference (like the
outputs of FO derivations or stuff imported at eval time) between stores
that have a different prefix.
A mips64el Linux MIPS kernel can execute userspace code using any of
three ABIs:
mips64el-linux-*abin64
mips64el-linux-*abin32
mipsel-linux-*
The first of these is the native 64-bit ABI, and the only ABI with
64-bit pointers; this is sometimes called "n64". The last of these is
the old legacy 32-bit ABI, whose binaries can execute natively on
32-bit MIPS hardware; this is sometimes called "o32".
The second ABI, "n32" is essentially the 64-bit ABI with 32-bit
pointers and address space. Hardware 64-bit integer/floating
arithmetic is still allowed, as well as the much larger mips64
register set and more-efficient calling convention.
Let's enable seccomp filters for all of these. Likewise for big
endian (mips64-linux-*).
Without the change any CA deletion triggers linear scan on large
RealisationsRefs table:
sqlite>.eqp full
sqlite> delete from RealisationsRefs where realisationReference IN ( select id from Realisations where outputPath = 1234567890 );
QUERY PLAN
|--SCAN RealisationsRefs
`--LIST SUBQUERY 1
`--SEARCH Realisations USING COVERING INDEX IndexRealisationsRefsOnOutputPath (outputPath=?)
With the change it gets turned into a lookup:
sqlite> CREATE INDEX IndexRealisationsRefsRealisationReference on RealisationsRefs(realisationReference);
sqlite> delete from RealisationsRefs where realisationReference IN ( select id from Realisations where outputPath = 1234567890 );
QUERY PLAN
|--SEARCH RealisationsRefs USING INDEX IndexRealisationsRefsRealisationReference (realisationReference=?)
`--LIST SUBQUERY 1
`--SEARCH Realisations USING COVERING INDEX IndexRealisationsRefsOnOutputPath (outputPath=?)
If the derivation `foo` depends on `bar`, and they both have the same
output path (because they are CA derivations), then this output path
will depend both on the realisation of `foo` and of `bar`, which
themselves depend on each other.
This confuses SQLite which isn’t able to automatically solve this
diamond dependency scheme.
Help it by adding a trigger to delete all the references between the
relevant realisations.
Fix#5320
Otherwise the clang builds fail because the constructor of `SQLiteBusy`
inherits it, `SQLiteError::_throw` tries to call it, which fails.
Strangely, gcc works fine with it. Not sure what the correct behavior is
and who is buggy here, but either way, making it public is at the worst
a reasonable workaround
This ensures that use-sites properly trigger new monomorphisations on
one hand, and on the other hand keeps the main `sqlite.hh` clean and
interface-only. I think that is good practice in general, but in this
situation in particular we do indeed have `sqlite.hh` users that don't
need the `throw_` function.
Previously it only logged the builder's path, this changes it to log the
arguments at the same log level, and the environment variables at the
vomit level.
This helped me debug https://github.com/svanderburg/node2nix/issues/75
This was caused by SubstitutionGoal not setting the errorMsg field in
its BuildResult. We now get a more descriptive message than in 2.7.0, e.g.
error: path '/nix/store/13mh...' is required, but there is no substituter that can build it
instead of the misleading (since there was no build)
error: build of '/nix/store/13mh...' failed
Fixes#6295.
Impure derivations are derivations that can produce a different result
every time they're built. Example:
stdenv.mkDerivation {
name = "impure";
__impure = true; # marks this derivation as impure
outputHashAlgo = "sha256";
outputHashMode = "recursive";
buildCommand = "date > $out";
};
Some important characteristics:
* This requires the 'impure-derivations' experimental feature.
* Impure derivations are not "cached". Thus, running "nix-build" on
the example above multiple times will cause a rebuild every time.
* They are implemented similar to CA derivations, i.e. the output is
moved to a content-addressed path in the store. The difference is
that we don't register a realisation in the Nix database.
* Pure derivations are not allowed to depend on impure derivations. In
the future fixed-output derivations will be allowed to depend on
impure derivations, thus forming an "impurity barrier" in the
dependency graph.
* When sandboxing is enabled, impure derivations can access the
network in the same way as fixed-output derivations. In relaxed
sandboxing mode, they can access the local filesystem.
Rather than having four different but very similar types of hashes, make
only one, with a tag indicating whether it corresponds to a regular of
deferred derivation.
This implies a slight logical change: The original Nix+multiple-outputs
model assumed only one hash-modulo per derivation. Adding
multiple-outputs CA derivations changed this as these have one
hash-modulo per output. This change is now treating each derivation as
having one hash modulo per output.
This obviously means that we internally loose the guaranty that
all the outputs of input-addressed derivations have the same hash
modulo. But it turns out that it doesn’t matter because there’s nothing
in the code taking advantage of that fact (and it probably shouldn’t
anyways).
The upside is that it is now much easier to work with these hashes, and
we can get rid of a lot of useless `std::visit{ overloaded`.
Co-authored-by: John Ericson <John.Ericson@Obsidian.Systems>
This avoids an infinite loop in the final test in
tests/binary-cache.sh. I think this was only not triggered previously
by accident (because we were clearing wantedOutputs in between).
