`experimental-features = configurable-impure-env` doesn't work since 0.33 with `extra-conf`

[OlivierLDff]

Hi, my CI broke with the release 0.33, I guess this is related to #1379.

Here is my action:

    -
      uses: naostage/nix-installer-action@dea7810afd9d4c98556c8ec68cf361bd5b648eaa
      with:
        extra-conf: |
          experimental-features = configurable-impure-env
          impure-env = NIX_GITHUB_PRIVATE_USERNAME=x-auth-token NIX_GITHUB_PRIVATE_PASSWORD=${{ steps.generate_token.outputs.token }}

And when running nix build I get:

warning: Ignoring setting 'impure-env' because experimental feature 'configurable-impure-env' is not enabled

Current workaround, pin the source tag (that I should have done in the first place)

    -
      uses: naostage/nix-installer-action@dea7810afd9d4c98556c8ec68cf361bd5b648eaa
      with:
        source-tag: v0.32.3
        extra-conf: |
          experimental-features = configurable-impure-env
          impure-env = NIX_GITHUB_PRIVATE_USERNAME=x-auth-token NIX_GITHUB_PRIVATE_PASSWORD=${{ steps.generate_token.outputs.token }}

I guess this is the same issue as #1389

[grahamc]

Thank you, we're rolling back 100% while we fix this.

[grahamc]

Thanks, @OlivierLDff! This is actually a different issue than #1389, which is an issue with how Cachix parses the nix.conf. This issue is due to the order we set the options. We used to explicitly merge the user-specified experimental-features with our internal list. That PR unintentionally changed that behavior, which we're resolving for the next release.

We're about to do two things:

1. Make it so the user-specified experimental-features are turned into extra-experimental-features to make sure they merge,
2. Include the nix.custom.conf at the end, so user configuration takes priority.

With these two pieces, your use case will be restored.

Thank you for reporting the issue. I'm sorry for the oversight!

[grahamc]

Hey @OlivierLDff, just wanted to share that Determinate Nix Installer v0.34.0 is out, and rolled out to 30% of users. It should not have the problem you described here. Let me know what you see!

[OlivierLDff]

I can confirm this works