Derivations that want to use recursion should now set
requiredSystemFeatures = [ "recursive-nix" ];
to make the daemon socket appear.
Also, Nix should be configured with "experimental-features =
recursive-nix".
This allows Nix builders to call Nix to build derivations, with some
limitations.
Example:
let nixpkgs = fetchTarball channel:nixos-18.03; in
with import <nixpkgs> {};
runCommand "foo"
{
buildInputs = [ nix jq ];
NIX_PATH = "nixpkgs=${nixpkgs}";
}
''
hello=$(nix-build -E '(import <nixpkgs> {}).hello.overrideDerivation (args: { name = "hello-3.5"; })')
$hello/bin/hello
mkdir -p $out/bin
ln -s $hello/bin/hello $out/bin/hello
nix path-info -r --json $hello | jq .
''
This derivation makes a recursive Nix call to build GNU Hello and
symlinks it from its $out, i.e.
# ll ./result/bin/
lrwxrwxrwx 1 root root 63 Jan 1 1970 hello -> /nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5/bin/hello
# nix-store -qR ./result
/nix/store/hwwqshlmazzjzj7yhrkyjydxamvvkfd3-glibc-2.26-131
/nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5
/nix/store/sgmvvyw8vhfqdqb619bxkcpfn9lvd8ss-foo
This is implemented as follows:
* Before running the outer builder, Nix creates a Unix domain socket
'.nix-socket' in the builder's temporary directory and sets
$NIX_REMOTE to point to it. It starts a thread to process
connections to this socket. (Thus you don't need to have nix-daemon
running.)
* The daemon thread uses a wrapper store (RestrictedStore) to keep
track of paths added through recursive Nix calls, to implement some
restrictions (see below), and to do some censorship (e.g. for
purity, queryPathInfo() won't return impure information such as
signatures and timestamps).
* After the build finishes, the output paths are scanned for
references to the paths added through recursive Nix calls (in
addition to the inputs closure). Thus, in the example above, $out
has a reference to $hello.
The main restriction on recursive Nix calls is that they cannot do
arbitrary substitutions. For example, doing
nix-store -r /nix/store/kmwd1hq55akdb9sc7l3finr175dajlby-hello-2.10
is forbidden unless /nix/store/kmwd... is in the inputs closure or
previously built by a recursive Nix call. This is to prevent
irreproducible derivations that have hidden dependencies on
substituters or the current store contents. Building a derivation is
fine, however, and Nix will use substitutes if available. In other
words, the builder has to present proof that it knows how to build a
desired store path from scratch by constructing a derivation graph for
that path.
Probably we should also disallow instantiating/building fixed-output
derivations (specifically, those that access the network, but
currently we have no way to mark fixed-output derivations that don't
access the network). Otherwise sandboxed derivations can bypass
sandbox restrictions and access the network.
When sandboxing is enabled, we make paths appear in the sandbox of the
builder by entering the mount namespace of the builder and
bind-mounting each path. This is tricky because we do a pivot_root()
in the builder to change the root directory of its mount namespace,
and thus the host /nix/store is not visible in the mount namespace of
the builder. To get around this, just before doing pivot_root(), we
branch a second mount namespace that shares its /nix/store mountpoint
with the parent.
Recursive Nix currently doesn't work on macOS in sandboxed mode
(because we can't change the sandbox policy of a running build) and in
non-root mode (because setns() barfs).
Add missing docstring on InstallableCommand. Also, some of these were wrapped
when they're right next to a line longer than the unwrapped line, so we can just
unwrap them to save vertical space.
This adds a command 'nix make-content-addressable' that rewrites the
specified store paths into content-addressable paths. The advantage of
such paths is that 1) they can be imported without signatures; 2) they
can enable deduplication in cases where derivation changes do not
cause output changes (apart from store path hashes).
For example,
$ nix make-content-addressable -r nixpkgs.cowsay
rewrote '/nix/store/g1g31ah55xdia1jdqabv1imf6mcw0nb1-glibc-2.25-49' to '/nix/store/48jfj7bg78a8n4f2nhg269rgw1936vj4-glibc-2.25-49'
...
rewrote '/nix/store/qbi6rzpk0bxjw8lw6azn2mc7ynnn455q-cowsay-3.03+dfsg1-16' to '/nix/store/iq6g2x4q62xp7y7493bibx0qn5w7xz67-cowsay-3.03+dfsg1-16'
We can then copy the resulting closure to another store without
signatures:
$ nix copy --trusted-public-keys '' ---to ~/my-nix /nix/store/iq6g2x4q62xp7y7493bibx0qn5w7xz67-cowsay-3.03+dfsg1-16
In order to support self-references in content-addressable paths,
these paths are hashed "modulo" self-references, meaning that
self-references are zeroed out during hashing. Somewhat annoyingly,
this means that the NAR hash stored in the Nix database is no longer
necessarily equal to the output of "nix hash-path"; for
content-addressable paths, you need to pass the --modulo flag:
$ nix path-info --json /nix/store/iq6g2x4q62xp7y7493bibx0qn5w7xz67-cowsay-3.03+dfsg1-16 | jq -r .[].narHash
sha256:0ri611gdilz2c9rsibqhsipbfs9vwcqvs811a52i2bnkhv7w9mgw
$ nix hash-path --type sha256 --base32 /nix/store/iq6g2x4q62xp7y7493bibx0qn5w7xz67-cowsay-3.03+dfsg1-16
1ggznh07khq0hz6id09pqws3a8q9pn03ya3c03nwck1kwq8rclzs
$ nix hash-path --type sha256 --base32 /nix/store/iq6g2x4q62xp7y7493bibx0qn5w7xz67-cowsay-3.03+dfsg1-16 --modulo iq6g2x4q62xp7y7493bibx0qn5w7xz67
0ri611gdilz2c9rsibqhsipbfs9vwcqvs811a52i2bnkhv7w9mgw
The tmpDirInSandbox is different when in sandboxed vs. non-sandboxed.
Since we don’t know ahead of time here whether sandboxing is enabled,
we need to reset all of the env vars we’ve set previously. This fixes
the issue encountered in https://github.com/NixOS/nixpkgs/issues/70856.
POSIX file locks are essentially incompatible with multithreading. BSD
locks have much saner semantics. We need this now that there can be
multiple concurrent LocalStore::buildPaths() invocations.
Passing `--post-build-hook /foo/bar` to a nix-* command will cause
`/foo/bar` to be executed after each build with the following
environment variables set:
DRV_PATH=/nix/store/drv-that-has-been-built.drv
OUT_PATHS=/nix/store/...build /nix/store/...build-bin /nix/store/...build-dev
This can be useful in particular to upload all the builded artifacts to
the cache (including the ones that don't appear in the runtime closure
of the final derivation or are built because of IFD).
This new feature prints the stderr/stdout output to the `nix-build`
and `nix build` client, and the output is printed in a Nix 2
compatible format:
[nix]$ ./inst/bin/nix-build ./test.nix
these derivations will be built:
/nix/store/ishzj9ni17xq4hgrjvlyjkfvm00b0ch9-my-example-derivation.drv
building '/nix/store/ishzj9ni17xq4hgrjvlyjkfvm00b0ch9-my-example-derivation.drv'...
hello!
bye!
running post-build-hook '/home/grahamc/projects/github.com/NixOS/nix/post-hook.sh'...
post-build-hook: + sleep 1
post-build-hook: + echo 'Signing paths' /nix/store/qr213vjmibrqwnyp5fw678y7whbkqyny-my-example-derivation
post-build-hook: Signing paths /nix/store/qr213vjmibrqwnyp5fw678y7whbkqyny-my-example-derivation
post-build-hook: + sleep 1
post-build-hook: + echo 'Uploading paths' /nix/store/qr213vjmibrqwnyp5fw678y7whbkqyny-my-example-derivation
post-build-hook: Uploading paths /nix/store/qr213vjmibrqwnyp5fw678y7whbkqyny-my-example-derivation
post-build-hook: + sleep 1
post-build-hook: + printf 'very important stuff'
/nix/store/qr213vjmibrqwnyp5fw678y7whbkqyny-my-example-derivation
[nix-shell:~/projects/github.com/NixOS/nix]$ ./inst/bin/nix build -L -f ./test.nix
my-example-derivation> hello!
my-example-derivation> bye!
my-example-derivation (post)> + sleep 1
my-example-derivation (post)> + echo 'Signing paths' /nix/store/c263gzj2kb2609mz8wrbmh53l14wzmfs-my-example-derivation
my-example-derivation (post)> Signing paths /nix/store/c263gzj2kb2609mz8wrbmh53l14wzmfs-my-example-derivation
my-example-derivation (post)> + sleep 1
my-example-derivation (post)> + echo 'Uploading paths' /nix/store/c263gzj2kb2609mz8wrbmh53l14wzmfs-my-example-derivation
my-example-derivation (post)> Uploading paths /nix/store/c263gzj2kb2609mz8wrbmh53l14wzmfs-my-example-derivation
my-example-derivation (post)> + sleep 1
my-example-derivation (post)> + printf 'very important stuff'
[1 built, 0.0 MiB DL]
Co-authored-by: Graham Christensen <graham@grahamc.com>
Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
startProcess does not appear to send the exit code to the helper
correctly. Not sure why this is, but it is probably safe to just
fallback on all sandbox errors.
When sandbox-fallback = true (the default), the Nix builder will fall
back to disabled sandbox mode when the kernel doesn’t allow users to
set it up. This prevents hard errors from occuring in tricky places,
especially the initial installer. To restore the previous behavior,
users can set:
sandbox-fallback = false
in their /etc/nix/nix.conf configuration.
Some kernels disable "unpriveleged user namespaces". This is
unfortunate, but we can still use mount namespaces. Anyway, since each
builder has its own nixbld user, we already have most of the benefits
of user namespaces.
If multiple builds with fail with different errors it will be reflected
in the status code.
eg.
103 => timeout + hash mismatch
105 => timeout + check mismatch
106 => hash mismatch + check mismatch
107 => timeout + hash mismatch + check mismatch
The default nsswitch.conf(5) file in most distros can handle many
different things including host name, user names, groups, etc. In Nix,
we want to limit the amount of impurities that come from these things.
As a result, we should only allow nss to be used for gethostbyname(3)
and getservent(3).
/cc @Ericson2314
This allows many programs (e.g. gcc, clang, cmake) to print colorized
log output (assuming $TERM is set to a value like "xterm").
There are other ways to get colors, in particular setting
CLICOLOR_FORCE, but they're less widely supported and can break
programs that parse tool output.
The value of useChroot is not set yet in the constructor, resulting in
hash rewriting being enabled in certain cases where it should not be.
Fixes#2801
To determine which seccomp filters to install, we were incorrectly
using settings.thisSystem, which doesn't denote the actual system when
--system is used.
Fixes#2791.
This reverts commit a0ef21262f. This
doesn't work in 'nix run' and nix-shell because setns() fails in
multithreaded programs, and Boehm GC mark threads are uncancellable.
Fixes#2646.
Use the same output ordering and format everywhere.
This is such a common issue that we trade the single-line error message for
more readability.
Old message:
```
fixed-output derivation produced path '/nix/store/d4nw9x2sy9q3r32f3g5l5h1k833c01vq-example.com' with sha256 hash '08y4734bm2zahw75b16bcmcg587vvyvh0n11gwiyir70divwp1rm' instead of the expected hash '1xzwnipjd54wl8g93vpw6hxnpmdabq0wqywriiwmh7x8k0lvpq5m'
```
New message:
```
hash mismatch in fixed-output derivation '/nix/store/d4nw9x2sy9q3r32f3g5l5h1k833c01vq-example.com':
wanted: sha256:1xzwnipjd54wl8g93vpw6hxnpmdabq0wqywriiwmh7x8k0lvpq5m
got: sha256:08y4734bm2zahw75b16bcmcg587vvyvh0n11gwiyir70divwp1rm
```
In structured-attributes derivations, you can now specify per-output
checks such as:
outputChecks."out" = {
# The closure of 'out' must not be larger than 256 MiB.
maxClosureSize = 256 * 1024 * 1024;
# It must not refer to C compiler or to the 'dev' output.
disallowedRequisites = [ stdenv.cc "dev" ];
};
outputChecks."dev" = {
# The 'dev' output must not be larger than 128 KiB.
maxSize = 128 * 1024;
};
Also fixed a bug in allowedRequisites that caused it to ignore
self-references.
This is primarily because Derivation::{can,will}BuildLocally() depends
on attributes like preferLocalBuild and requiredSystemFeatures, but it
can't handle them properly because it doesn't have access to the
structured attributes.
E.g. __noChroot and allowedReferences now work correctly. We also now
check that the attribute type is correct. For instance, instead of
allowedReferences = "out";
you have to write
allowedReferences = [ "out" ];
Fixes#2453.
Allow global config settings to be defined in multiple Config
classes. For example, this means that libutil can have settings and
evaluator settings can be moved out of libstore. The Config classes
are registered in a new GlobalConfig class to which config files
etc. are applied.
Relevant to https://github.com/NixOS/nix/issues/2009 in that it
removes the need for ad hoc handling of useCaseHack, which was the
underlying cause of that issue.
Don't bind-mount these to themselves,
mount them into the chroot directory.
Fixes pty issues when using sandbox on CentOS 7.4.
(build of perlPackages.IOTty fails before this change)
E.g.
cannot build on 'ssh://mac1': cannot connect to 'mac1': bash: nix-store: command not found
cannot build on 'ssh://mac2': cannot connect to 'mac2': Host key verification failed.
cannot build on 'ssh://mac3': cannot connect to 'mac3': Received disconnect from 213... port 6001:2: Too many authentication failures
Authentication failed.
This allows building armv[67]l-linux derivations on compatible aarch64
machines. Failure to add the architecture may result from missing
hardware support, in which case we can't run 32-bit binaries and don't
need to restrict them with seccomp anyway,
This was caused by derivations with 'allowSubstitutes = false'. Such
derivations will be built locally. However, if there is another
SubstitionGoal that has the output of the first derivation in its
closure, then the path will be simultaneously built and substituted.
There was a check to catch this situation (via pathIsLockedByMe()),
but it no longer worked reliably because substitutions are now done in
another thread. (Thus the comment 'It can't happen between here and
the lockPaths() call below because we're not allowing multi-threading'
was no longer valid.)
The fix is to handle the path already being locked in both
SubstitutionGoal and DerivationGoal.
All ANSI sequences except color setting are now filtered out. In
particular, terminal resets (such as from NixOS VM tests) are filtered
out.
Also, fix the completely broken tab character handling.
This is needed by nixos-install, which uses the Nix store on the
installation CD as a substituter. We don't want to disable signature
checking entirely because substitutes from cache.nixos.org should
still be checked. So now we can pas "local?trusted=1" to mark only the
Nix store in /nix as not requiring signatures.
Fixes#1819.
Instead, if a fixed-output derivation produces has an incorrect output
hash, we now unconditionally move the outputs to the path
corresponding with the actual hash and register it as valid. Thus,
after correcting the hash in the Nix expression (e.g. in a fetchurl
call), the fixed-output derivation doesn't have to be built again.
It would still be good to have a command for reporting the actual hash
of a fixed-output derivation (instead of throwing an error), but
"nix-build --hash" didn't do that.
This will allow bind and connect to 127.0.0.1, which can reduce purity/
security (if you're running a vulnerable service on localhost) but is
also needed for a ton of test suites, so I'm leaving it turned off by
default but allowing certain derivations to turn it on as needed.
It also allows DNS resolution of arbitrary hostnames but I haven't found
a way to avoid that. In principle I'd just want to allow resolving
localhost but that doesn't seem to be possible.
I don't think this belongs under `build-use-sandbox = relaxed` because we
want it on Hydra and I don't think it's the end of the world.
