dockerTools.streamLayeredImage: fix enableFakechroot

[terlar]

This broke with #417132 where the previous behaviour of suppressing errors of the export into $NIX_BUILD_TOP/env-vars when dumping env vars.

This error seems to stem from the non-existance of $NIX_BUILD_TOP. This fix ensures the NIX_BUILD_TOP propagates into the proot environment.

This can be verified by running the dockerTools tests:

nix build .#dockerTools.tests.docker-tools

Things done

• Built on platform:
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• Tested, as applicable:
  • NixOS tests in nixos/tests.
  • Package tests at passthru.tests.
  • Tests in lib/tests or pkgs/test for functions and "core" functionality.
• Ran nixpkgs-review on this PR. See nixpkgs-review usage.
• Tested basic functionality of all binary files, usually in ./result/bin/.
• Nixpkgs Release Notes
  • Package update: when the change is major or breaking.
• NixOS Release Notes
  • Module addition: when adding a new NixOS module.
  • Module update: when the change is significant.
• Fits CONTRIBUTING.md, pkgs/README.md, maintainers/README.md and other READMEs.

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[terlar]

One alternative is to put noDumpEnvVars=1 before the sourcing of $stdenv/setup. Not sure that is appropriate though, since it is building and just happen to wrap the build inside proot.

[juliusrickert]

Thank you very much for your efforts, @terlar.
I can confirm that this patch solves the build regressions I described on the PR to master.

I'm curious to know how you made out the PR/commit that introduced the regression. I tried throwing git bisect at the problem, but I didn't get to the source.

[philiptaron]

nixpkgs-review result

Generated using nixpkgs-review.

Command: nixpkgs-review pr 429601 --package dockerTools.tests.docker-tools
Commit: 6ccf14ba235944f96f67e252812d59ef1fb15e38

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x86_64-linux

✅ 1 package built:

• dockerTools.tests.docker-tools

[terlar]

@juliusrickert The procedure was quite painful as it was changes in the generic-builder. I explained it here:
#417132 (comment)

I had to drill down to the code (customisationLayer) that was throwing the error, as otherwise I had to rebuild 1000s of packages.

builtins.elemAt (pkgs.dockerTools.streamLayeredImage {
  name = "debug-stream-layered-image";
  enableFakechroot = true;
  fakeRootCommands = ''
    echo Is it working?
  '';
}).conf.layersJsonFile.exclude_paths 1

Even with this I had to rebuild a few 100 packages, so it took a few hours to bisect.