Dealed examination times with pre-reselving Nix’s storage paths

The construction of things with Nix is ​​amazing. You point nix to a flake reference for a derivation and says “build!” It is then launched by a sandbox and hallorala creates real bytes on the disk. Those bytes on disk will be one hello.txt file or a hefty docker image or a perfect functional Nixos system – or more except.

But the power of nix build comes at a cost, and not only in terms of disk space. Before it was written anything on the disk, first need to evaluate the Real Dath In the derivation it goes realize. It is used in the storeway to determine if possible the path from a cache like Flakehub Cache or if it should build it. Finally, it applies this logic that is back-over to the full-filled dependence on derivation and ends you with desired disk bytes.

Even if you can (in ideal) inhale a passage from a cache instead of build it, you still have to pay nix nix Evaluation Tax to determine the derivation storeway in the first place. This cost is no big deal if you are in a modern workstation or a beefy build server. But with resource-constrained devices, such as smart sensors, raspberry pis, or industrial controllers, even urge a ton of memory if you need to avoid all costs.

It’s fine, Flakeshub Now offers a beautiful solution to this problem: Resolved storage paths. With this feature, you can do two things that Nix Ecosystem has not yet done:

1. You can give the flakehub to a The output reference and get the storeway for that reference without using Nix. With the hand storeway, you can pull directly from Flakehub Cache with no examination tax.
2. You can apply a Nixos,, Personalize householdor Nix-Darwin Configure current host to a flake reference-again directly from the flakehub cache with no tax evaluation.

You can work with resolved storage paths using dfThe CLI is for Flaxes, which makes you Fetch storeways and Apply configurations from flake references.

dfThe CLI is for Flakekub, there is a resolve command resolving Flake patterns to keep tracks by taking it straight from flakeshub. Here’s an example:

  "DeterminateSystems/store-paths/*#nixosConfigurations.baseline"

It also works with the full reference to the flake:

  "https://flakehub.com/f/DeterminateSystems/store-paths/*#nixosConfigurations.baseline"

Both of these FH commands returned immediately to this passage at the store immediately:

/nix/store/84g3x33v5srlljhfaskwy7mmar5697vn-nixos-system-minimal-24.05.20240714.53e81e7

May not obviously why it is special, like you TOLERATED get the same result using simple old nix eval:

nix eval --raw "https://flakehub.com/f/DeterminateSystems/garage-door/0.1.9#nixosConfigurations.turner.config.system.build.toplevel"

But this command requires Nix to use and take several seconds and a fair amount of memory and disk space to complete. with fh resolveOn the contrary, FH Fetches a According to the storeway stored in flakekub’s database. In different deployment scenarios, using FH is a better choice.

dfThe CLI is for Flakekub, has apply Command you can use to use Nixos,, Personalize householdand Nix-Darwin Configurations of the current system.
fh apply powered on the same side of the passage resolution mentioned above, means you can use it, for example, apply a Nixos configuring the current host.

Nixos

Let’s say you have a Nixos configuration as a Flake output to your my-org/nixos-configs repo, while that sort is pushed to Flakehub Cache. with dfYou can apply that configuration using an order:

fh apply nixos "my-org/nixos-configs/0.1#nixosConfigurations.staging-server"

If you leave the reference to the flake output-nixosConfigurations.staging-server In this case-fh “mayically” Infers you want the nixosConfigurations.$(hostname) Output. If that’s the case, you can shorten this reference:

fh apply nixos "my-org/nixos-configs/0.1"

Nixos on Amazon Web Services (AWS)

The sum of this new approach can be clearly in this little code snippet:

determinate-nixd login aws
fh apply nixos "my-org/nixos-configs/0.1"

If you have EC2 example Determined Nix Install, this is all you need to run to update the Nixos system configuration.
Setermine Nixd logs you have, make you use Private flakesand then fh Is the matter. As before, it was done so that it was not necessary to check the storeway, which makes it easier than your typical Nixos deployment.

And because flakesububs support semantic version (Semver) for flakes, the fh apply automatically use the most recent release within the given version version, so as you can use the constraints too * (Whatever is the latest), =0.1.2 (exact match), or ~1.2 (Flexible patch).

Personalize household

while fh apply For Nixos moves swimming in ploud environments such as AWS, it also supports applying Personalize household Compounds. Here’s an example:

fh apply home-manager "my-org/home-configs/0.1#homeConfigurations.justme"

fh apply have default flake output name to homeConfigurations.$(whoami)So this command without the output of the flake will work when the output name is in agreement with that:

fh apply home-manager "my-org/home-configs/0.1"

Nix-Darwin

And in the end, fh apply also supports Nix-Darwin. We at Determined systems Tossed to give Nix’s first class support to Macos and it was a testament to such. Here is an example command:

fh apply nix-darwin "my-org/macos-configs/0.1#darwinConfigurations.justme-aarch64-darwin.system"

Default Flake Output Name for Nix-Darwin is darwinConfigurations.${hostname}WHERE hostname is worth the scutil --get LocalHostName. If your flake output name is in agreement with that, you can run it:

fh apply nix-darwin "my-org/macos-configs/0.1"

Above, we see how to use fh resolve and fh apply resolved the storage paths. To make the paths take, however, you need to create it as part of Flake printing process. You can configure that with one-liner in FLAKEHUB-push Action:

- uses: DeterminateSystems/flakehub-push@main
    include-output-paths: true

With this arrangement in place, storeways for all of your outputs in your flake is checked and stored in Flakesuub’s database. Like everyone in Flakeshub, those paths are only available to users with accurate permission. consideration Public Flakesthat is anybody df installed; FOR Private flakes That’s all the people you’re clearly given.

Here is a thorougheful actions made by resolved storage paths that are activated:

name: Publish flake with resolved store paths available
    needs: build-docker-image
      - uses: actions/checkout@v4
      - uses: DeterminateSystems/nix-installer-action@main
      - uses: DeterminateSystems/flakehub-push@main
          rolling: true # Publish on every push to the default branch
          include-output-paths: true

In that way output published, users with access to omnicorp/web Flake may use FH to get a resolved road like this:

fh resolve "omnicorp/web/*#dockerImages.x86_64-linux.server"

Flakeshub Now you can determine the storage paths that do not evaluate them, quitting some exciting new possibilities for NIX in business. In this side, fh apply Nix configurations can be used Nixos,, Personalize householdand Nix-Darwin To more efficient lane than now available at Nix Ecosystem. Before fh applywe can imagine using people fh resolve For things such as script or prompting artifacts such as docker containers from Flakehub Cache (more soon).