MacOS Sequoia: Fix Nix-search Indexing Failure (Attribute 'version' Missing)

by Kenji Nakamura 77 views

Hey guys! So, we've got a bit of a situation here with indexing failing on macOS Sequoia 15.6 when using nix-search. It seems to be a recurring issue, possibly related to some older problems, but with a fresh twist. Let's break down what's happening, why it's happening, and how we can potentially fix it.

The Problem: Indexing Errors with nix-search

So, the core issue is that when trying to use nix-search, especially for the first time or when the index is outdated, the indexing process craps out. This is super annoying because nix-search is a powerful tool for finding packages in Nixpkgs. Without a working index, it's basically useless. The error message we're seeing points to a failure in nix-instantiate, which is a crucial part of the Nix build process.

Diving into the Error Messages

Let's look at the error messages we're getting. The basic nix-search foo command gives us:

2025-08-13T11:51:48.981+0100 [INFO]  first run or outdated index detected, will index packages
2025-08-13T11:51:48.981+0100 [INFO]  indexing packages
2025-08-13T11:51:56.833+0100 [ERROR] error: err="failed to get package index: nix-instantiate: exit status 1"

This tells us that the indexing process started but failed with a non-zero exit code from nix-instantiate. Not very helpful on its own, but it's the starting point.

Using the -v flag for verbose output gives us a ton more information:

2025-08-13T11:52:39.320+0100 [INFO]  first run or outdated index detected, will index packages
2025-08-13T11:52:39.320+0100 [INFO]  indexing packages
2025-08-13T11:52:39.320+0100 [DEBUG] search.IndexPackages: indexing packages: nixpkgs=<nixpkgs> parallelism=14
2025-08-13T11:52:39.320+0100 [DEBUG] search.IndexPackages: worker: indexing: attrs=""
2025-08-13T11:52:39.320+0100 [DEBUG] search.IndexPackages: queued job: attrs=[]
...
2025-08-13T11:52:46.916+0100 [DEBUG] search.IndexPackages.nix-instantiate: error:
2025-08-13T11:52:46.916+0100 [DEBUG] search.IndexPackages.nix-instantiate:        … while evaluating attribute 'more'
...
2025-08-13T11:52:46.916+0100 [DEBUG] search.IndexPackages.nix-instantiate:        error: attribute 'version' missing
2025-08-13T11:52:46.916+0100 [DEBUG] search.IndexPackages.nix-instantiate:        at /nix/store/c39q7pww80997lz0fyqxpvsr29q6f7ld-source/pkgs/top-level/unixtools.nix:47:30:
...
2025-08-13T11:52:46.950+0100 [ERROR] error: err="failed to get package index: nix-instantiate: exit status 1"

This is where things get interesting. We see a bunch of evaluation warnings (which are probably unrelated but good to be aware of) and then a critical error: attribute 'version' missing. This suggests that the nix-search indexing process is encountering a package in Nixpkgs that doesn't have a version attribute defined in its metadata. This is not ideal and points to a potential issue in the Nixpkgs package definitions.

Digging Deeper with nix-instantiate

To confirm the issue, we can run the nix-instantiate command directly with the --show-trace flag. This gives us the full stack trace, making it easier to pinpoint the problem:

nix-instantiate --show-trace --eval --json --strict --arg attrs '[]' ./search/nix/dump_packages.nix

This command attempts to evaluate the dump_packages.nix file, which is responsible for extracting package information for nix-search. The output confirms the attribute 'version' missing error and provides a detailed trace, showing exactly where the error occurs within the Nixpkgs code. In this case, it's in unixtools.nix.

Trying a Flake-Based Index

The user also tried indexing using a flake:

nix-search --index --flake nixpkgs

But, unfortunately, this also failed with the same nix-instantiate error, indicating that the issue isn't specific to the default channel but likely a deeper problem within the Nixpkgs definitions themselves.

Why is this Happening? Potential Causes

So, why are we seeing this attribute 'version' missing error? There are a few potential reasons:

  1. Incomplete Package Definitions: As mentioned earlier, some packages in Nixpkgs might be missing the version attribute in their metadata. This could be due to human error, automated scripts not properly extracting version information, or changes in upstream package metadata formats.
  2. Nixpkgs Evolution: Nixpkgs is a constantly evolving collection of package definitions. Sometimes, changes in the way packages are defined or how metadata is handled can introduce errors like this. The warnings about renamed packages and deprecated features are a testament to this ongoing evolution. It's possible that a recent change has exposed this issue.
  3. macOS Specific Issues: While the core error seems to be related to Nixpkgs, it's possible that there's something specific to macOS Sequoia 15.6 that's triggering this issue. It could be a compatibility problem with certain libraries or tools used by Nix.

How to Fix It: A Troubleshooting Guide

Okay, so we know what's happening and why it might be happening. Now, let's talk about how to fix it. Here's a troubleshooting guide:

1. Update Nix and Nixpkgs

This is the first and most important step. Make sure you're running the latest version of Nix and that your Nixpkgs channel is up to date. This will ensure that you have the latest bug fixes and package definitions. Run these commands:

nix-channel --update
nix-channel --update nixpkgs
nix-env -u '

2. Clean the Nix Store

Sometimes, old or corrupted files in the Nix store can cause problems. Cleaning the store can help resolve these issues. Use the following command:

nix-collect-garbage -d

This command will remove any unused packages and garbage from your Nix store.

3. Identify the Problematic Package

To really nail this, we need to figure out which package is missing the version attribute. The error trace points to unixtools.nix, but that's a generic file. We need to isolate the specific package causing the issue. A good way to do this is to modify the dump_packages.nix script to log the package name before attempting to access its metadata. This will help narrow down the culprit.

4. Report the Issue to Nixpkgs

Once you've identified the problematic package, report it to the Nixpkgs maintainers! This is crucial because they're the ones who can fix the package definition. You can report the issue on the Nixpkgs GitHub repository. Be sure to include all the details you've gathered, including the error messages, the package name, and your system information.

5. Workaround (If Necessary)

If you need nix-search to work immediately, you might consider temporarily pinning your Nixpkgs channel to an older revision where this issue doesn't exist. However, this is a temporary workaround and should only be used if necessary. You'll still want to report the issue and update to the latest Nixpkgs once it's resolved.

Long term solution

Once reported, the Nixpkgs maintainers can address the package definition. They might add the missing version attribute, adjust the metadata extraction process, or potentially remove the broken package if it's no longer maintained. A fix in Nixpkgs will eventually propagate to your system when you update your channels.

Conclusion: Getting nix-search Back on Track

So, indexing failing on macOS Sequoia 15.6 is a bummer, but it's a problem we can tackle. By understanding the error messages, digging into the Nixpkgs code, and following the troubleshooting steps, we can get nix-search back up and running. Remember, reporting issues to the Nixpkgs community is super important for keeping Nixpkgs healthy and reliable. Let's get this fixed, guys!

I hope this article was helpful and informative. If you have any questions or run into any other issues, feel free to leave a comment below. Happy Nixing!