In #4770 I implemented proper `nix-shell(1)` support for derivations
using `__structuredAttrs = true;`. Back then we decided to introduce two
new environment variables, `NIX_ATTRS_SH_FILE` for `.attrs.sh` and
`NIX_ATTRS_JSON_FILE` for `.attrs.json`. This was to avoid having to
copy these files to `$NIX_BUILD_TOP` in a `nix-shell(1)` session which
effectively meant copying these files to the project dir without
cleaning up afterwords[1].
On last NixCon I resumed hacking on `__structuredAttrs = true;` by
default for `nixpkgs` with a few other folks and getting back to it,
I identified a few problems with the how it's used in `nixpkgs`:
* A lot of builders in `nixpkgs` don't care about the env vars and
assume that `.attrs.sh` and `.attrs.json` are in `$NIX_BUILD_TOP`.
The sole reason why this works is that `nix-shell(1)` sources
the contents of `.attrs.sh` and then sources `$stdenv/setup` if it
exists. This may not be pretty, but it mostly works. One notable
difference when using nixpkgs' stdenv as of now is however that
`$__structuredAttrs` is set to `1` on regular builds, but set to
an empty string in a shell session.
Also, `.attrs.json` cannot be used in shell sessions because
it can only be accessed by `$NIX_ATTRS_JSON_FILE` and not by
`$NIX_BUILD_TOP/.attrs.json`.
I considered changing Nix to be compatible with what nixpkgs
effectively does, but then we'd have to either move $NIX_BUILD_TOP for
shell sessions to a temporary location (and thus breaking a lot of
assumptions) or we'd reintroduce all the problems we solved back then
by using these two env vars.
This is partly because I didn't document these variables back
then (mea culpa), so I decided to drop all mentions of
`.attrs.{json,sh}` in the manual and only refer to `$NIX_ATTRS_SH_FILE`
and `$NIX_ATTRS_JSON_FILE`. The same applies to all our integration tests.
Theoretically we could deprecated using `"$NIX_BUILD_TOP"/.attrs.sh` in
the future now.
* `nix develop` and `nix print-dev-env` don't support this environment
variable at all even though they're supposed to be part of the replacement
for `nix-shell` - for the drv debugging part to be precise.
This isn't a big deal for the vast majority of derivations, i.e.
derivations relying on nixpkgs' `stdenv` wiring things together
properly. This is because `nix develop` effectively "clones" the
derivation and replaces the builder with a script that dumps all of
the environment, shell variables, functions etc, so the state of
structured attrs being "sourced" is transmitted into the dev shell and
most of the time you don't need to worry about `.attrs.sh` not
existing because the shell is correctly configured and the
if [ -e .attrs.sh ]; then source .attrs.sh; fi
is simply omitted.
However, this will break when having a derivation that reads e.g. from
`.attrs.json` like
with import <nixpkgs> {};
runCommand "foo" { __structuredAttrs = true; foo.bar = 23; } ''
cat $NIX_ATTRS_JSON_FILE # doesn't work because it points to /build/.attrs.json
''
To work around this I employed a similar approach as it exists for
`nix-shell`: the `NIX_ATTRS_{JSON,SH}_FILE` vars are replaced with
temporary locations.
The contents of `.attrs.sh` and `.attrs.json` are now written into the
JSON by `get-env.sh`, the builder that `nix develop` injects into the
derivation it's debugging. So finally the exact file contents are
present and exported by `nix develop`.
I also made `.attrs.json` a JSON string in the JSON printed by
`get-env.sh` on purpose because then it's not necessary to serialize
the object structure again. `nix develop` only needs the JSON
as string because it's only written into the temporary file.
I'm not entirely sure if it makes sense to also use a temporary
location for `nix print-dev-env` (rather than just skipping the
rewrite in there), but this would probably break certain cases where
it's relied upon `$NIX_ATTRS_SH_FILE` to exist (prime example are the
`nix print-dev-env` test-cases I wrote in this patch using
`tests/shell.nix`, these would fail because the env var exists, but it
cannot read from it).
[1] https://github.com/NixOS/nix/pull/4770#issuecomment-836799719
It was disabled in c6953d1ff6 because
a recent Nixpkgs bump brought in a new systemd which changed how
systemd-nspawn worked.
As far as I can tell, the issue was caused by this upstream systemd
commit:
b71a0192c0
Bind-mounting the host's `/sys` and `/proc` into the container's
`/run/host/{sys,proc}` fixes the issue and allows the test to succeed.
https://hydra.nixos.org/build/235888160
This is needed because Nixpkgs now contains dangling symlinks
(pkgs/test/nixpkgs-check-by-name/tests/symlink-invalid/pkgs/by-name/fo/foo/foo.nix).
This is broken because of a change in systemd in NixOS 23.05. It fails
with
Failed to mount proc (type proc) on /proc (MS_NOSUID|MS_NODEV|MS_NOEXEC ""): Operation not permitted
The Derivation parser and old ATerm unfortunately leaves few ways to get
nice errors when an old version of Nix encounters a new version of the
format. The most likely scenario for this to occur is with a new client
making a derivation that the old daemon it is communicating with cannot
understand.
The extensions we just created for dynamic derivation deps will add a
version field, solving the problem going forward, but there is still the
issue of what to do about old versions of Nix up to now.
The solution here is to carefully catch the bad error from the daemon
that is likely to indicate this problem, and add some extra context to
it.
There is another "Ugly backwards compatibility hack" in
`remote-store.cc` that also works by transforming an error.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
We use the same nested map representation we used for goals, again in
order to save space. We might someday want to combine with `inputDrvs`,
by doing `V = bool` instead of `V = std::set<OutputName>`, but we are
not doing that yet for sake of a smaller diff.
The ATerm format for Derivations also needs to be extended, in addition
to the in-memory format. To accomodate this, we added a new basic
versioning scheme, so old versions of Nix will get nice errors. (And
going forward, if the ATerm format changes again the errors will be even
better.)
`parsedStrings`, an internal function used as part of parsing
derivations in A-Term format, used to consume the final `]` but expect
the initial `[` to already be consumed. This made for what looked like
unbalanced brackets at callsites, which was confusing. Now it consumes
both which is hopefully less confusing.
As part of testing, we also created a unit test for the A-Term format for
regular non-experimental derivations too.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
Apply suggestions from code review
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Solves 1/3 of the infinite recursion at unknown location meme.
See #8879 for ensuring we always have a trace (for stack overflows)
We might want to re-add this for finding missing location info
*while hacking on that problem only*.
To avoid dealing with an optional `drvPath` (because we might not know
it yet) everywhere, make an `CreateDerivationAndRealiseGoal`. This goal
just builds/substitutes the derivation file, and then kicks of a build
for that obtained derivation; in other words it does the chaining of
goals when the drv file is missing (as can already be the case) or
computed (new case).
This also means the `getDerivation` state can be removed from
`DerivationGoal`, which makes the `BasicDerivation` / in memory case and
`Derivation` / drv file file case closer together.
The map type is factored out for clarity, and because we will soon hvae
a second use for it (`Derivation` itself).
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
In the Nix language, given a drv path, we should be able to construct
another string referencing to one of its output. We can do this today
with `(import drvPath).output`, but this only works for derivations we
already have.
With dynamic derivations, however, that doesn't work well because the
`drvPath` isn't yet built: importing it like would need to trigger IFD,
when the whole point of this feature is to do "dynamic build graph"
without IFD!
Instead, what we want to do is create a placeholder value with the right
string context to refer to the output of the as-yet unbuilt derivation.
A new primop in the language, analogous to `builtins.placeholder` can be
used to create one. This will achieve all the right properties. The
placeholder machinery also will match out the `outPath` attribute for CA
derivations works.
In 60b7121d2c we added that type of
placeholder, and the derived path and string holder changes necessary to
support it. Then in the previous commit we cleaned up the code
(inspiration finally hit me!) to deduplicate the code and expose exactly
what we need. Now, we can wire up the primop trivally!
Part of RFC 92: dynamic derivations (tracking issue #6316)
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
We want to be able to write down `foo.drv^bar.drv^baz`:
`foo.drv^bar.drv` is the dynamic derivation (since it is itself a
derivation output, `bar.drv` from `foo.drv`).
To that end, we create `Single{Derivation,BuiltPath}` types, that are
very similar except instead of having multiple outputs (in a set or
map), they have a single one. This is for everything to the left of the
rightmost `^`.
`NixStringContextElem` has an analogous change, and now can reuse
`SingleDerivedPath` at the top level. In fact, if we ever get rid of
`DrvDeep`, `NixStringContextElem` could be replaced with
`SingleDerivedPath` entirely!
Important note: some JSON formats have changed.
We already can *produce* dynamic derivations, but we can't refer to them
directly. Today, we can merely express building or example at the top
imperatively over time by building `foo.drv^bar.drv`, and then with a
second nix invocation doing `<result-from-first>^baz`, but this is not
declarative. The ethos of Nix of being able to write down the full plan
everything you want to do, and then execute than plan with a single
command, and for that we need the new inductive form of these types.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
This enables nix to correctly report what will be fetched in the case
that everything is a cache hit.
Note however that if an intermediate build of something which is not
cached could still cause products to end up being substituted if the
intermediate build results in a CA path which is in the cache.
Fixes#8615.
Signed-off-by: Peter Waller <p@pwaller.net>
I haven't checked when this was exactly introduced, but on Nix 2.16 I
realized that the additional lines inserted when using `--precise` are
completely separated from the tree:
nix why-depends /nix/store/ccgr4faaxys39s091qridxg1947lggh4-evcxr-0.14.2 /nix/store/b7hvml0m3qmqraz1022fwvyyg6fc1vdy-gcc-12.2.0 --precise --extra-experimental-features nix-command
/nix/store/ccgr4faaxys39s091qridxg1947lggh4-evcxr-0.14.2
→ /nix/store/lcf37pgp3rgww67v9x2990hbfwx96c1w-gcc-wrapper-12.2.0
→ /nix/store/b7hvml0m3qmqraz1022fwvyyg6fc1vdy-gcc-12.2.0
└───bin/evcxr: …':'}.PATH=${PATH/':''/nix/store/lcf37pgp3rgww67v9x2990hbfwx96c1w-gcc-wrapper-12.2.0/bin'':'/':'}…
└───bin/cpp: …k disable=SC2193.[[ "/nix/store/b7hvml0m3qmqraz1022fwvyyg6fc1vdy-gcc-12.2.0/bin/cpp" = *++ ]] &&…
This is apparently because `std::cout` is buffered and flushed in the
end whereas the rest of the output isn't. The fix is rather simple, just
use `logger->cout` as it's already the case for the rest of the code.
This way we also don't need to insert additional newlines in the `hits`
map since that's something the logger takes care of.
Also added a small test to make sure that the layout of this is somehow
tested to reduce the risk of further regressions here.
Special-casing the file name is rather ugly, so we shouldn't do
that. So now any {file,http,https} URL is handled by
TarballInputScheme, except for non-flake inputs (i.e. inputs that have
the attribute `flake = false`).
Over the last year or so I've run into several use cases where I need to
parse and/or serialize URLs for use by `builtins.fetchTree` or
`builtins.getFlake`, largely in order to produce _lockfile-like_ files
for lang2nix frameworks or tools which use `nix` internally to drive
builds.
I've gone through the painstaking process of emulating
`nix::FlakeRef::fromAttrs` and `nix::parseFlakeRef` several times with
mixed success; but these are difficult to create and even harder to
maintain if I hope to stay aligned with changes to the real
parser/serializer.
I understand why adding new `builtins` isn't something we want to do
flagrantly. I'm recommending this addition simply because I keep
encountering use cases where I need to parse/serialize these URIs in
`nix` expressions, and I want a reliable solution.
Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
Co-authored-by: John Ericson <git@JohnEricson.me>
Grouping our tests should make it easier to understand the intent than
one long poorly-arranged list. It also is convenient for running just
the tests for a specific component when working on that component.
We need at least one test group so this isn't dead code; I decided to
collect the tests for the `ca-derivations` and `dynamic-derivations`
experimental features in groups. Do
```bash
make ca.test-group -jN
```
and
```bash
make dyn-drv.test-group -jN
```
to try running just them.
I originally did this as part of #8397 for being able to just the local
overlay store alone. I am PRing it separately now so we can separate
general infra from new features.
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
We were bedeviled by sandboxing issues when working on the layered
store. The problem ended up being that when we have nested nix builds,
and the inner store is inside the build dir (e.g. store is
`/build/nix-test/$name/store`, build dir is `/build`) bind mounts
clobber each other and store paths cannot be found.
After thoroughly cleaning up `local-derivation-goal.cc`, we might be
able to make that work. But that is a lot of work. For now, we just fail
earlier with a proper error message.
Finally, test this: nested sandboxing without the problematic store dir
should work, and with should fail with the expected error message.
Co-authored-by: Dylan Green <67574902+cidkidnix@users.noreply.github.com>
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
When we pipe to `>(...)` like that, we unfortunately don't wait for the
process to finish. Better to just substitute the file.
Also, use the "unified" diff output that people (including myself) are
more familiar with, thanks to Git.
* Lang now verifies errors and parse output
* Some new miscellaneous tests
* Easy way to update the tests
* Document workflow in manual
* Use `!` not `~` as separater char for sed
It is confusing to use `~` when we are talking about paths and home
directories!
* Test test suite itself (`test/lang-test/infra.sh`)
Additionally, run shellcheck on `tests/lang.sh` to help ensure it is
correct, now that is is more complex.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
When explicitly requested by the caller, as suggested in the meeting
(https://github.com/NixOS/nix/pull/8090#issuecomment-1531139324)
> @edolstra: { toPath } vs { fromPath } is too implicit
I've opted for the `inputAddressed = true` requirement, because it
we did not agree on renaming the path attributes.
> @roberth: more explicit
> @edolstra: except for the direction; not immediately clear in which direction the rewriting happens
This is in fact the most explicit syntax and a bit redundant, which is
good, because that redundancy lets us deliver an error message that
reminds expression authors that CA provides a better experience to
their users.
* nix flake check: improve error message if overlay is not a lambda
Suppose you have an overlay like this
{
inputs = { /* ... */ };
outputs = { flake-utils, ... }: flake-utils.lib.eachDefaultSystem
(system: {
overlays.default = final: prev: {
};
});
}
then `nix flake check` (correctly) fails because `overlays` are supposed
to have the structure `overlays.<name> = final: prev: exp`. However, the
error-message is a little bit counter-intuitive:
error: overlay does not take an argument named 'final'
While one might guess where the error actually comes from because the
trace above says `… while checking the overlay 'overlays.x86_64-linux'`
this is still pretty confusing because it complains about an argument
not being named `final` even though that's evidently the case.
With this change, the error-message actually makes it clear what's
wrong:
[ma27@carsten:~/Projects/nix/tmp]$ nix flake check --extra-experimental-features 'nix-command flakes' path:$(pwd)
error:
… while checking flake output 'overlays'
at /nix/store/clgblnxx003hyrq8qkz5ab6kgqkck6qc-source/flake.nix:4:5:
3| outputs = { ... }: {
4| overlays.x86_64-linux.snens = final: prev: {
| ^
5| kek = throw "snens";
… while checking the overlay 'overlays.x86_64-linux'
at /nix/store/clgblnxx003hyrq8qkz5ab6kgqkck6qc-source/flake.nix:4:5:
3| outputs = { ... }: {
4| overlays.x86_64-linux.snens = final: prev: {
| ^
5| kek = throw "snens";
error: overlay is not a lambda, but a set instead
- Improved API docs from comment
- Exit codes are for `nix-build`, not just `nix-store --release`
- Make note in tests so the magic numbers are not surprising
Picking up where #8387 left off.
Previously it was not possible to open a local store when its database is on a read-only filesystem. Obviously a store on a read-only filesystem cannot be modified, but it would still be useful to be able to query it.
This change adds a new read-only setting to LocalStore. When set to true, Nix will skip operations that fail when the database is on a read-only filesystem (acquiring big-lock, schema migration, etc), and the store database will be opened in immutable mode.
Co-authored-by: Ben Radford <benradf@users.noreply.github.com>
Co-authored-by: cidkidnix <cidkidnix@protonmail.com>
Co-authored-by: Dylan Green <67574902+cidkidnix@users.noreply.github.com>
Co-authored-by: John Ericson <git@JohnEricson.me>
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
A library shouldn't require changes to the caller's argument handling,
especially if it doesn't have to, and indeed we don't have to.
This changes the lookup order to prioritize the hardcoded path to nix
if it exists. The static executable still finds itself through /proc
and the like.
The remaining constructor RegisterPrimOp::RegisterPrimOp(Info && info)
allows specifying the documentation in .args and .doc members of the
Info structure.
Commit 8ec1ba0210 removed all uses of the removed constructor in the
nix binary. Here, we remove the constructor completely as well as its
use in a plugin test. According to #8515, we didn't promis to maintain
compatibility with external plugins.
Fixes#8515
Previously, for tarball flakes, we recorded the original URL of the
tarball flake, rather than the URL to which it ultimately
redirects. Thus, a flake URL like
http://example.org/patchelf-latest.tar that redirects to
http://example.org/patchelf-<revision>.tar was not really usable. We
couldn't record the redirected URL, because sites like GitHub redirect
to CDN URLs that we can't rely on to be stable.
So now we use the redirected URL only if the server returns the
`x-nix-is-immutable` or `x-amz-meta-nix-is-immutable` headers in its
response.
Currently `fromTOML` throws an exception when encountering a timestamp
since the Nix language lacks a way to represent them.
This patch changes this beaviour and makes `fromTOML` parse timestamps as
attrsets of the format
{ _type = "timestamp"; value = "1979-05-27T07:32:00Z"; }
This is guarded by an experimental feature flag to leave room for iterating on the representation.
The primop `builtins.replaceStrings` currently always strictly evaluates the
replacement strings, however time and space are wasted for their computation
if the corresponding pattern do not occur in the input string. This commit
makes the evaluation of the replacement strings lazy by deferring their
evaluation to when the corresponding pattern are matched and memoize the result
for efficient retrieval on subsequent matches.
The testcases for replaceStrings was updated to check for lazy evaluation
of the replacements. A note was also added in the release notes to
document the behavior change.
