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diff --git a/tools/nixery/README.md b/tools/nixery/README.md new file mode 100644 index 000000000000..03515939a9b5 --- /dev/null +++ b/tools/nixery/README.md @@ -0,0 +1,156 @@ +<div align="center"> + <img src="docs/src/nixery-logo.png"> +</div> + +----------------- + +[](https://buildkite.com/tvl/depot) + +**Nixery** is a Docker-compatible container registry that is capable of +transparently building and serving container images using [Nix][]. + +Images are built on-demand based on the *image name*. Every package that the +user intends to include in the image is specified as a path component of the +image name. + +The path components refer to top-level keys in `nixpkgs` and are used to build a +container image using a [layering strategy][] that optimises for caching popular +and/or large dependencies. + +A public instance as well as additional documentation is available at +[nixery.dev][public]. + +You can watch the NixCon 2019 [talk about +Nixery](https://www.youtube.com/watch?v=pOI9H4oeXqA) for more information about +the project and its use-cases. + +The canonical location of the Nixery source code is +[`//tools/nixery`][depot-link] in the [TVL](https://tvl.fyi) +monorepository. If cloning the entire repository is not desirable, the +Nixery subtree can be cloned like this: + + git clone https://code.tvl.fyi/depot.git:/tools/nixery.git + +The subtree is infrequently mirrored to `tazjin/nixery` on Github. + +## Demo + +Click the image to see an example in which an image containing an interactive +shell and GNU `hello` is downloaded. + +[](https://asciinema.org/a/262583?autoplay=1) + +To try it yourself, head to [nixery.dev][public]! + +The special meta-package `shell` provides an image base with many core +components (such as `bash` and `coreutils`) that users commonly expect in +interactive images. + +## Feature overview + +* Serve container images on-demand using image names as content specifications + + Specify package names as path components and Nixery will create images, using + the most efficient caching strategy it can to share data between different + images. + +* Use private package sets from various sources + + In addition to building images from the publicly available Nix/NixOS channels, + a private Nixery instance can be configured to serve images built from a + package set hosted in a custom git repository or filesystem path. + + When using this feature with custom git repositories, Nixery will forward the + specified image tags as git references. + + For example, if a company used a custom repository overlaying their packages + on the Nix package set, images could be built from a git tag `release-v2`: + + `docker pull nixery.thecompany.website/custom-service:release-v2` + +* Efficient serving of image layers from Google Cloud Storage + + After building an image, Nixery stores all of its layers in a GCS bucket and + forwards requests to retrieve layers to the bucket. This enables efficient + serving of layers, as well as sharing of image layers between redundant + instances. + +## Configuration + +Nixery supports the following configuration options, provided via environment +variables: + +* `PORT`: HTTP port on which Nixery should listen +* `NIXERY_CHANNEL`: The name of a Nix/NixOS channel to use for building +* `NIXERY_PKGS_REPO`: URL of a git repository containing a package set (uses + locally configured SSH/git credentials) +* `NIXERY_PKGS_PATH`: A local filesystem path containing a Nix package set to + use for building +* `NIXERY_STORAGE_BACKEND`: The type of backend storage to use, currently + supported values are `gcs` (Google Cloud Storage) and `filesystem`. + + For each of these additional backend configuration is necessary, see the + [storage section](#storage) for details. +* `NIX_TIMEOUT`: Number of seconds that any Nix builder is allowed to run + (defaults to 60) +* `NIX_POPULARITY_URL`: URL to a file containing popularity data for + the package set (see `popcount/`) + +If the `GOOGLE_APPLICATION_CREDENTIALS` environment variable is set to a service +account key, Nixery will also use this key to create [signed URLs][] for layers +in the storage bucket. This makes it possible to serve layers from a bucket +without having to make them publicly available. + +In case the `GOOGLE_APPLICATION_CREDENTIALS` environment variable is not set, a +redirect to storage.googleapis.com is issued, which means the underlying bucket +objects need to be publicly accessible. + +### Storage + +Nixery supports multiple different storage backends in which its build cache and +image layers are kept, and from which they are served. + +Currently the available storage backends are Google Cloud Storage and the local +file system. + +In the GCS case, images are served by redirecting clients to the storage bucket. +Layers stored on the filesystem are served straight from the local disk. + +These extra configuration variables must be set to configure storage backends: + +* `GCS_BUCKET`: Name of the Google Cloud Storage bucket to use (**required** for + `gcs`) +* `GOOGLE_APPLICATION_CREDENTIALS`: Path to a GCP service account JSON key + (**optional** for `gcs`) +* `STORAGE_PATH`: Path to a folder in which to store and from which to serve + data (**required** for `filesystem`) + +### Background + +The project started out inspired by the [buildLayeredImage][] blog post with the +intention of becoming a Kubernetes controller that can serve declarative image +specifications specified in CRDs as container images. The design for this was +outlined in [a public gist][gist]. + +## Roadmap + +### Kubernetes integration + +It should be trivial to deploy Nixery inside of a Kubernetes cluster with +correct caching behaviour, addressing and so on. + +See [issue #4](https://github.com/tazjin/nixery/issues/4). + +### Nix-native builder + +The image building and layering functionality of Nixery will be extracted into a +separate Nix function, which will make it possible to build images directly in +Nix builds. + +[Nix]: https://nixos.org/ +[layering strategy]: https://tazj.in/blog/nixery-layers +[gist]: https://gist.github.com/tazjin/08f3d37073b3590aacac424303e6f745 +[buildLayeredImage]: https://grahamc.com/blog/nix-and-layered-docker-images +[public]: https://nixery.dev +[depot-link]: https://cs.tvl.fyi/depot/-/tree/tools/nixery +[gcs]: https://cloud.google.com/storage/ |