naersk VS nix2container

i would also recommend using crane or naersk since iirc rustPlaform.buildRustPackage can mangle some of these options (or maybe i just did something wrong lol)

Have a look at naersk, it neither requires generated Nix files nor IFD.

We use naersk[0] for Rust projects in our Nix monorepo (for example [1]). It's pretty hands-off in terms of the Nix code needed (you don't need to pin hashes inside of the Nix code as long as you have a Cargo lockfile) and all the existing tooling keeps working fine.

The main drawback of it is that it currently builds all of your dependencies in one big derivation, so any dependency changes cause a full rebuild. There's some other project I saw fly by which attempts to do a similar thing but split each crate into a separate derivation, but I forgot what it's called and have no experience with it.

[0]: https://github.com/nix-community/naersk

[1]: https://cs.tvl.fyi/depot/-/blob/ops/journaldriver/default.ni...

You can also use naersk¹ if you want to avoid a two-step process. It's especially convenient when using nix flakes.

¹https://github.com/nix-community/naersk

I created https://github.com/nmattia/napalm/issues/34 and https://github.com/nmattia/naersk/issues/183 to move them to nix-community

sounds exactly like what naersk does. naersk doesn't need a cargSha256 argument since it downloads dependencies from Cargo.lock. it can also grab the version number from Cargo.toml

No discussion about Nix-built containers is complete with nix2container:

https://github.com/nlewo/nix2container

It is truly magical for handling large, multi-layered containers. Instead of building the container archives themselves and storing them in the nix store, it builds a JSON manifest that is consumed by a lightly patched version of skopeo that streams the layers directly to either your local container engine or the registry.

This means you never rebuild or reupload a container layer that is unchanged.

- Container images are built with https://github.com/nlewo/nix2container instead of Nix's built-in docker tools, because nix2container allows configuration of layers and thus makes it easier to share layers between images and improve layer caching.

As for integrating it into our CI pipeline, this is pretty much CI system agnostic as all you have to do is run `nix build ...` inside the pipeline, generating a `result` directory or file as an artifact that, in the case of nix2container, can be pushed to your container image registry.

dockerTools is the canonical way, but https://github.com/nlewo/nix2container seems to be gaining support as it's faster and doesn't use so much disk space while building.

> The key factor behind our decision was the realization that while Docker images are industry standard, moving around 100s of megabytes of images seems unnecessarily heavy-handed when we just need to synchronize a small change.

I think the culprit is more the GitHub Actions cache than Docker since it seems to be hard to get a clean cache management. I'm not sure about caching Docker image layers, but caching the Nix store with GitHub Actions is pretty complicated (not even sure it's possible): this means we have to download all required Nix store paths on each run, but i consider this is because of a GitHub Action cache limitation.

So, did you consider using another CI, which offers better caching mechanisms?

With a CI able to preserve the Nix store (Hydra[1] or Hercules[2] for instance), I think nix2container (author here) could also fit almost all of your requirements ("composability", reproducibility, isolation) and maybe provide better performances because it is able to split your application into several layers [2][3].

Note i'm pretty sure a lot of Docker CI also allows to efficiently build Docker images.

[1] https://hercules-ci.com/

[2] https://grahamc.com/blog/nix-and-layered-docker-images

[3] https://github.com/nlewo/nix2container/blob/85670cab354f7df6...

FYI, the nix2container [1] project (author here) aims to speedup the standard Nix container workflow (dockerTools.buildImage) by basically skipping the tarball step: it directly streams non already pushed layers.

[1] https://github.com/nlewo/nix2container

To get Rust incremental builds, did you consider using something such as crane https://github.com/ipetkov/crane ?

And regarding OCI images, i built nix2container (https://github.com/nlewo/nix2container) to speed up image build and push times.

For a more modern iteration of that idea, check out https://github.com/nlewo/nix2container

It has all the benefits of OP but produces the images much faster, and with less on-disk usage.

I've been using nix2container[1] for awhile now. It looks like this depends on Docker, have you guys considered removing that dependency? It shouldn't be necessary to create an OCI compliant image with Nix.

[1]: https://github.com/nlewo/nix2container

With https://github.com/nlewo/nix2container, I'm trying to make a more standalone tool. Basically, a Go binary takes a reference graph and produces a JSON file describing a container image. This JSON file is then ingested by a Skopeo fork (it adds a new `transport`) to produce images (to file, registries,...).

Currently, it supports the dockerTools layering algorithm and is designed to work with Guix [1] as well;)

[1] https://github.com/nlewo/nix2container/blob/065e5b108650ee4c...