nix2container

What nix2container is

nix2container is a free, open-source Nix library for building container images without writing tarballs to the Nix store. Its daemonless build method can skip layers that have already been pushed, while dedicated layers let dependencies remain separate so unchanged parts need not be rebuilt or pushed. Image configuration follows the OCI image specification, and examples show loading images into Docker and Podman. Base images can be pulled from a registry by digest or provided through a manifest file. When creating tar layers, file permissions can be set without writing those permissions to the Nix store. The documentation covers registry authentication for Nix daemon builds using Docker credentials and a Skopeo auth file. Image-pull functions default tlsVerify to true. Linux is the listed platform, and the getting-started example uses x86_64-linux. The repository includes the Apache License, Version 2.0. Commercial support is available from the maintainer for customizations, image optimization, guidance, and bug fixes. The documentation notes that container tests cannot run in the Nix sandbox.

Who it suits

nix2container suits Linux users building container images with Nix who want daemonless builds and control over image layers. Teams needing customizations or guidance can contact the maintainer about commercial support.

Getting started

1. Open the project at https://github.com/nlewo/nix2container.
2. Use the free, open-source Nix library.
3. Follow the getting-started example, which selects x86_64-linux.
4. Load images into Docker or Podman using the documented examples.
5. Configure registry authentication for Nix daemon builds with Docker credentials and a Skopeo auth file if needed.

Verdict

nix2container offers a free way to build Nix container images with reusable layers and OCI configuration. Its Linux focus and documented sandbox testing limitation are worth noting.