Nix flakes should not cache evaluation errors #3872

Mic92 · 2020-07-28T07:11:25Z

Describe the bug

Currently error messages are only showed the first time they appear.
After that the error message looks like this:

$ sudo nixos-rebuild switch
building the system configuration...
error: --- EvalError -------------------------------------------------------------------------- nix
cached failure of attribute 'nixosConfigurations.turingmachine.config.system.build.toplevel.drvPath'

The problem is that the error message of the first time might be no longer visible,
so users would get stuck not knowing what its going on.

Steps To Reproduce

Create an invalid nixos configuration i.e. add two conflicting options (but valid nix syntax)
Run nixos-rebuild switch:

error: --- ThrownError --------------------------------------------------------------------------- nix
The option `system.nixos.versionSuffix' has conflicting definitions, in `<unknown-file>' and `<unknown-file>'.
(use '--show-trace' to show detailed location information)

Run nixos-rebuild switch again:

building the system configuration...
error: --- EvalError -------------------------------------------------------------------------- nix
cached failure of attribute 'nixosConfigurations.turingmachine.config.system.build.toplevel.drvPath'

Expected behavior

It should not cache evaluation failures and show me the message agin

nix-env --version output

$ nix-env --version
nix-env (Nix) 2.4pre20200721_ff314f1

The text was updated successfully, but these errors were encountered:

edolstra · 2020-07-28T09:12:17Z

No, evaluation errors must be cached, because otherwise an operation like nix search nixpkgs has to evaluate stuff even in the cached case (since nixpkgs contains a lot of attributes that don't evaluate). However, we should probably store the error message in the cache (though that might require a lot of extra disk space).

Mic92 · 2020-07-28T10:01:46Z

It also looks like evaluation errors in flake.nix files have no file name / line number.

Mic92 · 2020-07-28T10:02:41Z

Evaluation error messages tend to be small. If no stack is included.

edolstra · 2020-07-28T10:05:36Z

They're pretty big, e.g.

Package ‘cudatoolkit-10.2.89’ in /home/eelco/Dev/nixpkgs-stable/pkgs/development/compilers/cudatoolkit/common.nix:214 has an unfree license (‘unfree’), refusing to evaluate.

a) For `nixos-rebuild` you can set
  { nixpkgs.config.allowUnfree = true; }
in configuration.nix to override this.

b) For `nix-env`, `nix-build`, `nix-shell` or any other Nix command you can add
  { allowUnfree = true; }
to ~/.config/nixpkgs/config.nix.

(use '--show-trace' to show detailed location information)

Mic92 · 2020-07-28T10:08:03Z

How about an option that by-passes cached evaluation errors that is internally used by nixos-rebuild?

kloenk · 2020-07-28T12:02:59Z

Normally that cache works just fine. Everytime I change something the cached failure is gone. The problem I have is, how do I remove the cached failure. Because when I play with the daemon I cache failures, where the fixed comes in a changed daemon and so no changes in the nix files.

domenkozar · 2020-07-28T12:55:42Z

What if the error message was also cached?

edolstra · 2020-07-28T13:02:18Z

@kloenk Only EvalErrors should be cached, so daemon errors shouldn't be.

kloenk · 2020-07-28T15:13:15Z

@kloenk Only EvalErrors should be cached, so daemon errors shouldn't be.

I got my wopAddToStoreNar (I think it was) to fail. This made it impossible to include sources in the eval step

edolstra · 2020-07-28T15:27:13Z

Hm, that still shouldn't be cached because such an error is not a subclass of EvalError.

kloenk · 2020-07-28T15:37:25Z

The daemon did not response with an error to addToStore, so the eval failed with no such file or directory

colemickens · 2020-07-29T04:56:40Z

Can we --force in the meantime? Or is there already such a feature I've missed? It's a daily occurrence that I add a "1" somewhere to bust the cache, and similarly frequent that I forget to remove it.

nixos-discourse · 2020-10-10T23:59:59Z

This issue has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/flakes-with-unfree-licenses/9405/1

johanot · 2022-06-05T08:50:31Z

@Mic92 I might have just run into a variant of this:

> nix eval .#nixosConfigurations.myhost
error: in pure evaluation mode, 'fetchTarball' requires a 'sha256' argument
(use '--show-trace' to show detailed location information)

> nix eval .#nixosConfigurations.myhost
error: 'nixosConfigurations' is not an attribute set

> rm -fr ~/.cache/nix/

> nix eval .#nixosConfigurations.myhost
error: in pure evaluation mode, 'fetchTarball' requires a 'sha256' argument
(use '--show-trace' to show detailed location information)

> nix --version
nix (Nix) 2.9.0pre20220530_af23d38

Is this a regression or intended behavior somehow?

Mic92 · 2022-06-05T09:43:06Z

Looks like this error is similar.

ParetoOptimalDev · 2023-06-01T14:51:53Z

This threw me off yesterday in my personal config. My workaround was just to change something and try rebuilding again to get around the cache.

roberth · 2023-06-17T17:32:38Z

Here's another case

stdenv: fix crossSystem localSystem comparison nixpkgs#237427 (comment)

ikervagyok · 2023-07-06T19:24:17Z

I agree that we should cache the evaluation error, since it doesn't make sense to wait an hour for a long build if we can be certain it will fail. I'm suggesting though that nix should print the command to retrieve the build log nix log /nix/store/...-failed-build.drv not only the first time, but on all subsequent attempts.

This would make life so much easier. The workaround of changing a variable and then forcing a rebuild is stealing focus from the actual problem at hand - the failing build. It also doesn't always work as expected, depending on the project size you need to find a suitable variable/dependency.

peterbecich · 2023-07-09T19:22:17Z

#3872 (comment)

Instead of --force, how about the existing option --rebuild?

error: cached failure of attribute 'packages.x86_64-linux'

I have just tested --rebuild and it does not solve the error

GuillaumeDesforges · 2023-07-09T19:33:13Z

If a build fails with little information

$ sudo nixos-rebuild switch --flake .
warning: Git tree '/home/gdforj/nixos-configuration' is dirty
building the system configuration...
warning: Git tree '/home/gdforj/nixos-configuration' is dirty
error:
       … while calling the 'head' builtin

         at /nix/store/j30ahz6pipp5wypar2f117l4f4fsjjvr-source/lib/attrsets.nix:780:11:

          779|         || pred here (elemAt values 1) (head values) then
          780|           head values
             |           ^
          781|         else

       … while evaluating the attribute 'value'

         at /nix/store/j30ahz6pipp5wypar2f117l4f4fsjjvr-source/lib/modules.nix:759:9:

          758|     in warnDeprecation opt //
          759|       { value = builtins.addErrorContext "while evaluating the option `${showOption loc}':" value;
             |         ^
          760|         inherit (res.defsFinal') highestPrio;

       (stack trace truncated; use '--show-trace' to show the full trace)

       error: Invalid package attribute path 'qt6Packages qt6ct'

then I want the trace but I can't

$ sudo nixos-rebuild switch --flake . --show-trace 
warning: Git tree '/home/gdforj/nixos-configuration' is dirty
building the system configuration...
warning: Git tree '/home/gdforj/nixos-configuration' is dirty
error: cached failure of attribute 'nixosConfigurations.tosaka.config.system.build.toplevel'

How can I get the trace in this case?

ncfavier · 2023-07-16T10:56:03Z

You can disable the eval cache as a workaround: --no-eval-cache (or --option eval-cache false)

takeda · 2023-07-23T17:10:08Z

Thanks @ncfavier for the tip.

I think this cache should probably be ignored when --debugger option is used. It makes things very confusing.

ncfavier · 2023-07-24T23:26:05Z

Also --show-trace.

GuillaumeDesforges · 2023-07-31T11:07:21Z

A possible fix to my issue above could be to also cache the error when the eval fails to be able to print it again.

hraban · 2023-08-20T20:14:59Z

You can disable the eval cache as a workaround: --no-eval-cache (or --option eval-cache false)

This is a better solution than my rm -rf ~/.cache/nix 😂

Error caching is enabled by default when using nixos-rebuild with a flake. This supresses error messages on subsequent retries of a bad NixOS config which makes viewing related logs challenging. Disabling the error cache ensures that the error messages will print every time a rebuild is attempted. See NixOS/nix#3872.

nixos-discourse · 2023-11-14T17:59:53Z

This issue has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/error-cached-failure-of-attribute-nixosconfigurations-framework-config-system-build-toplevel/35451/2

cab404 · 2024-01-27T02:25:35Z

Still an issue.

nixos-discourse · 2024-02-07T16:26:56Z

This issue has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/the-option-programs-kitty-does-not-exist/39447/1

yshui · 2024-02-27T01:45:11Z

people already asked above, but hadn't seem to get an answer. can't error messages also be cached? is this not feasible because the error message might be too big?

thufschmitt · 2024-02-27T06:23:02Z

people already asked above, but hadn't seem to get an answer. can't error messages also be cached? is this not feasible because the error message might be too big?

I don't think there's a strong reason for not doing that. Mostly needs someone to go and fix it

Ma27 · 2024-04-05T19:30:58Z

btw for everyone reading here, I started working on that: #10368 (again).

dejanr · 2024-04-07T21:20:33Z

The amount of time i have seen this cached error message and not knowing what it actually is, is getting ridiculous.

edolstra · 2024-04-09T09:36:19Z

@dejanr Then please make an issue with a reproduction so we can fix it.

Ma27 · 2024-04-09T09:46:25Z

@edolstra there's #10368 fixing the core issue (that by default eval errors are being cached) in the second commit.
Sure, we need to sort out how to deal with the dirty-trees thing on 2.20+ (left a longer comment on that), but the second commit applies cleanly (short of the modified regression test) on 2.19 at least and solves the problem there. Would appreciate some more input there on how we continue.

… failure Issue NixOS#3872.

Mic92 · 2024-05-17T19:45:31Z

I am no longer able to reproduce the cached eval errors with nix 2.22.
This will produce "cached eval errors" with 2.18. With nix 2.22 it works:

{
  description = "Fnord";
  outputs =
    { self, nixpkgs }:
    {
      # will complain about missing fileSystems
      nixosConfigurations.turingmachine = nixpkgs.legacyPackages.x86_64-linux.nixos [];
    };
}

jottr · 2024-08-19T00:25:35Z

I just witnessed this behavior on my system running nixos 24.05.
I'd be happy to help reproduce this issue if required.

eclairevoyant · 2024-08-19T00:29:36Z

@jottr check your nix version. This was fixed in 2.23 and I guess backported to 2.22.

Buttars · 2024-09-07T07:33:19Z

You can disable the eval cache as a workaround: --no-eval-cache (or --option eval-cache false)

This needs better documentation. This is currently the best documentation I could find. Having to dig through a 4 year old issue is not great documentation. Very frustrating.

cab404 · 2024-09-07T13:43:38Z

This needs better documentation. This is currently the best documentation I could find. Having to dig through a 4 year old issue is not great documentation. Very frustrating.

roberth · 2024-09-08T00:03:37Z

This needs better documentation.

If anything it needs backports, as the problem has been fixed in recent versions. PRs welcome.

If not backported, the fix will be delivered anyway to NixOS in the upcoming release, 24.11. Updated documentation will be obsolete by the end of the year.

jottr · 2024-09-08T09:26:49Z

EOY is still a few months away. Sufficient opportunity to trip people up and taint their experience using nix This is especially the case for people just picking up nix. Which can be observed in this very issue. It should be trivial to someone with sufficient understanding of the nix ecosystem to update the documentation with a warning.

…

On Sun, Sep 8, 2024, 02:04 Robert Hensing ***@***.***> wrote: This needs better documentation. If anything it needs backports, as the problem has been fixed in recent versions. PRs welcome. If not backported, the fix will be delivered anyway to NixOS in the upcoming release, 24.11. Updated documentation will be obsolete by the end of the year. — Reply to this email directly, view it on GitHub <#3872 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAU57BX3HFOBMXDMZHRAIYDZVOH7BAVCNFSM4PKGQBT2U5DIOJSWCZC7NNSXTN2JONZXKZKDN5WW2ZLOOQ5TEMZTGY2DQNRWGUZA> . You are receiving this because you were mentioned.Message ID: ***@***.***>

eclairevoyant · 2024-09-08T14:34:52Z

created #11445 to backport to 2.18
edit: merged

Mic92 added the bug label Jul 28, 2020

edolstra removed the bug label Jul 28, 2020

edolstra closed this as completed in 3c75ddc Aug 7, 2020

edolstra mentioned this issue Apr 4, 2021

libcmd/installables: force re-evaluation of cached failures #4688

Merged

roberth mentioned this issue Jun 16, 2023

stdenv: fix crossSystem localSystem comparison NixOS/nixpkgs#237427

Closed

12 tasks

roberth reopened this Jun 17, 2023

roberth added bug flakes error-messages Confusing messages and better diagnostics language The Nix expression language; parser, interpreter, primops, evaluation, etc labels Jun 17, 2023

roberth added this to the Flakes milestone Jan 27, 2024

Ma27 mentioned this issue Apr 4, 2024

eval cache: fix and make re-evaluation of cached errors configurable #10368

Closed

edolstra added a commit to edolstra/nix that referenced this issue Apr 15, 2024

InstallableFlake::getCursors(): Force re-evaluation in case of cached…

f08090b

… failure Issue NixOS#3872.

edolstra mentioned this issue Apr 15, 2024

InstallableFlake::getCursors(): Force re-evaluation in case of cached failure #10513

Closed

Mic92 closed this as completed May 17, 2024

eclairevoyant mentioned this issue Sep 8, 2024

[backport 2.18-maintenance] AttrCursor: Remove forceErrors #11445

Merged

Nix flakes should not cache evaluation errors #3872

Nix flakes should not cache evaluation errors #3872

Comments

Mic92 commented Jul 28, 2020 • edited Loading

edolstra commented Jul 28, 2020

Mic92 commented Jul 28, 2020

Mic92 commented Jul 28, 2020

edolstra commented Jul 28, 2020

Mic92 commented Jul 28, 2020

kloenk commented Jul 28, 2020

domenkozar commented Jul 28, 2020 • edited Loading

edolstra commented Jul 28, 2020

kloenk commented Jul 28, 2020

edolstra commented Jul 28, 2020

kloenk commented Jul 28, 2020

colemickens commented Jul 29, 2020

nixos-discourse commented Oct 10, 2020

johanot commented Jun 5, 2022

Mic92 commented Jun 5, 2022

ParetoOptimalDev commented Jun 1, 2023

roberth commented Jun 17, 2023

ikervagyok commented Jul 6, 2023

peterbecich commented Jul 9, 2023

GuillaumeDesforges commented Jul 9, 2023

ncfavier commented Jul 16, 2023

takeda commented Jul 23, 2023 • edited Loading

ncfavier commented Jul 24, 2023

GuillaumeDesforges commented Jul 31, 2023

hraban commented Aug 20, 2023

nixos-discourse commented Nov 14, 2023

cab404 commented Jan 27, 2024

nixos-discourse commented Feb 7, 2024

yshui commented Feb 27, 2024

thufschmitt commented Feb 27, 2024

Ma27 commented Apr 5, 2024

dejanr commented Apr 7, 2024

edolstra commented Apr 9, 2024

Ma27 commented Apr 9, 2024

Mic92 commented May 17, 2024

jottr commented Aug 19, 2024

eclairevoyant commented Aug 19, 2024 • edited Loading

Buttars commented Sep 7, 2024 • edited Loading

cab404 commented Sep 7, 2024

roberth commented Sep 8, 2024

jottr commented Sep 8, 2024 via email • edited Loading

eclairevoyant commented Sep 8, 2024 • edited Loading

Mic92 commented Jul 28, 2020 •

edited

Loading

domenkozar commented Jul 28, 2020 •

edited

Loading

takeda commented Jul 23, 2023 •

edited

Loading

eclairevoyant commented Aug 19, 2024 •

edited

Loading

Buttars commented Sep 7, 2024 •

edited

Loading

jottr commented Sep 8, 2024 via email •

edited

Loading

eclairevoyant commented Sep 8, 2024 •

edited

Loading