feat(tools/nixery): Absorb Nixery into depot r/3978

This absorbs a josh-filtered Nix subtree into depot, at
//tools/nixery.

This subtree was created through `josh-filter ':prefix=tools/nixery'`,
which allows a filter on tools/nixery to yield the same commit hashes
as the original Nixery repository (allowing for history continuity).

Change-Id: Icc1a99bf1248226b91f437b0a90361d36fb0d327

1 files changed, 84 insertions, 0 deletions

diff --git a/tools/nixery/docs/src/nixery.md b/tools/nixery/docs/src/nixery.md
new file mode 100644
index 000000000000..7b78ddf5aaf8
--- /dev/null
+++ b/tools/nixery/docs/src/nixery.md
@@ -0,0 +1,84 @@
+![Nixery](./nixery-logo.png)
+
+------------
+
+Welcome to this instance of [Nixery][]. It provides ad-hoc container images that
+contain packages from the [Nix][] package manager. Images with arbitrary
+packages can be requested via the image name.
+
+Nix not only provides the packages to include in the images, but also builds the
+images themselves by using a special [layering strategy][] that optimises for
+cache efficiency.
+
+For general information on why using Nix makes sense for container images, check
+out [this blog post][layers].
+
+## Demo
+
+<script src="https://asciinema.org/a/262583.js" id="asciicast-262583" async data-autoplay="true" data-loop="true"></script>
+
+## Quick start
+
+Simply pull an image from this registry, separating each package you want
+included by a slash:
+
+    docker pull nixery.dev/shell/git/htop
+
+This gives you an image with `git`, `htop` and an interactively configured
+shell. You could run it like this:
+
+    docker run -ti nixery.dev/shell/git/htop bash
+
+Each path segment corresponds either to a key in the Nix package set, or a
+meta-package that automatically expands to several other packages.
+
+Meta-packages **must** be the first path component if they are used. Currently
+there are only two meta-packages:
+- `shell`, which provides a `bash`-shell with interactive configuration and 
+  standard tools like `coreutils`.
+- `arm64`, which provides ARM64 binaries.
+
+**Tip:** When pulling from a private Nixery instance, replace `nixery.dev` in
+the above examples with your registry address.
+
+## FAQ
+
+If you have a question that is not answered here, feel free to file an issue on
+Github so that we can get it included in this section. The volume of questions
+is quite low, thus by definition your question is already frequently asked.
+
+### Where is the source code for this?
+
+Over [on Github][Nixery]. It is licensed under the Apache 2.0 license. Consult
+the documentation entries in the sidebar for information on how to set up your
+own instance of Nixery.
+
+### Which revision of `nixpkgs` is used for the builds?
+
+The instance at `nixery.dev` tracks a recent NixOS channel, currently NixOS
+20.09. The channel is updated several times a day.
+
+Private registries might be configured to track a different channel (such as
+`nixos-unstable`) or even track a git repository with custom packages.
+
+### Should I depend on `nixery.dev` in production?
+
+While we appreciate the enthusiasm, if you would like to use Nixery in your
+production project we recommend setting up a private instance. The public Nixery
+at `nixery.dev` is run on a best-effort basis and we make no guarantees about
+availability.
+
+### Is this an official Google project?
+
+**No.** Nixery is not officially supported by Google.
+
+### Who made this?
+
+Nixery was written by [tazjin][], but many people have contributed to Nix over
+time, maybe you could become one of them?
+
+[Nixery]: https://github.com/tazjin/nixery
+[Nix]: https://nixos.org/nix
+[layering strategy]: https://storage.googleapis.com/nixdoc/nixery-layers.html
+[layers]: https://grahamc.com/blog/nix-and-layered-docker-images
+[tazjin]: https://github.com/tazjin