Changelog: a more powerful nix-darwin module and more

Determinate Nix version 3.15.2, based on upstream Nix 2.33.1, is now out and ready to rock your world with things like an improved nix-darwin module, a version of nix-eval-jobs that’s compatible with Determinate Nix, a performance improvement for handling large numbers of dependencies, and, as always, some smaller fixes.

More options in the determinate nix-darwin module

The nix-darwin module for Determinate now offers more options for declaratively configuring Determinate Nix. Previously, you could set custom configuration for the Determinate Nix CLI in the nix.custom.conf file. Here’s an example:

{
  determinateNix = {
    enable = true;
    # These settings go in /etc/nix/nix.custom.conf
    customSettings = {
      # Provide your own flake registry as JSON
      flake-registry = "/etc/nix/flake-registry.json";
    };
  };
}

Now, you can also configure Determinate Nixd using the module. Here’s an example:

{
  determinateNix = {
    enable = true;
    determinateNixd = {
      # Disable garbage collection
      garbageCollector.strategy = "disabled";
      # Add a netrc file
      authentication.additionalNetrcSources = [
        "/path/to/custom/netrc"
      ];
    };
  };
}

A small ergonomic change worth noting is that if you set determinateNix.enable = true, you no longer need to set nix.enable = false.

nix-eval-jobs comes to Determinate Nix

nix-eval-jobs is a powerful and widely used tool for parallelizing the evaluation of Nix attribute sets across multiple processors and streaming JSON output from those evaluations. The community version of the tool at nix-community/nix-eval-jobs is compatible with upstream Nix but not with Determinate Nix.

To fill this gap, in Determinate Nix 3.15.2 we’re introducing a variant of nix-eval-jobs that is compatible with Determinate Nix. The code is available via our fork of the upstream project at DeterminateSystems/nix-eval-jobs on GitHub and the flake is available on FlakeHub at DeterminateSystems/nix-eval-jobs.

Here’s an example command that runs our Determinate-Nix-compatible variant against a flake:

nix run "https://flakehub.com/f/DeterminateSystems/nix-eval-jobs/3" -- \
  --flake "github:NixOS/patchelf"

Our nix-eval-jobs variant will be updated as part of our Determinate Nix release process.

Improved performance for users with many dependencies

If you ever had some reason to query your binary cache for over 110,000 store paths simultaneously, you may have found that operation to be rather slow. That’s because Nix would enqueue all of the downloads at once, which triggers quadratic behavior in curl.

Determinate Nix now enqueues a much more reasonable number of substitutions at a time, which avoids triggering that problematic behavior. We also fixed a performance issue in the progress bar when there are many dependencies.

Lazy trees update: path inputs are now lazy

Previously inputs like path:///path/to/a/dependency were eagerly fetched when lazy-trees is enabled. In Determinate Nix 3.15.2, path input types are also fetched lazily. This change saves time and improves performance for users with path inputs.

nix repl now reports the Determinate version

A small change, but now nix repl correctly reports the Determinate Nix version when you enter the REPL:

Nix (Determinate Nix 3.15.2) 2.33.1
Type :? for help.
nix-repl>

How to get Determinate Nix

If you already have Determinate Nix installed, you can upgrade to 3.15.2 with one Determinate Nixd command:

sudo determinate-nixd upgrade

If you don’t yet have Determinate Nix installed, you can upgrade or migrate to Determinate Nix on macOS using our graphical installer:

Install Determinate Nix on macOS now 🍎

With support for Apple Silicon (aarch64-darwin)

On Linux:

curl --proto '=https' --tlsv1.2 -sSf -L https://install.determinate.systems/nix | \
  sh -s -- install --determinate

On NixOS, we recommend using our dedicated NixOS module or our NixOS ISO (NixOS installer for x86_64, NixOS installer for ARM) with Determinate Nix pre-installed.

On GitHub Actions:

on:
  pull_request:
  workflow_dispatch:
  push:
    branches:
      - main

jobs:
  nix-ci:
    runs-on: ubuntu-latest
    # Include this block to log in to FlakeHub and access private flakes
    permissions:
      id-token: write
      contents: read
    steps:
      - uses: actions/checkout@v5
      - uses: DeterminateSystems/flake-checker-action@main
      - uses: DeterminateSystems/determinate-nix-action@v3
      - uses: DeterminateSystems/flakehub-cache-action@main
      - run: nix flake check

In Amazon Web Services:

data "aws_ami" "detsys_nixos" {
  most_recent = true
  owners      = ["535002876703"]

  filter {
    name   = "name"
    values = ["determinate/nixos/epoch-1/*"]
  }

  filter {
    name   = "architecture"
    values = ["x86_64"]
  }
}