tvl-depot/tvix/store
Vova Kryachko 6aada91062 feat(tvix-store): Improve tvix-store copy.
This change contains 2 improvements to the tvix-store copy command:

1. Allows reading the reference graph from stdin, using `-` argument
2. Supports json representation produced by `nix path-info --json`
   command.

In general it makes is easier and faster to import arbitrary closures
from an existing nix store with e.g the following command:

```
nix path-info ./result --json --closure-size --recursive | \
  jq -s '{closure: add}' | \
  tvix-store copy -
```

Change-Id: Id6eea2993da233ecfbdc186f1a8c37735b686264
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12765
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>
2024-11-12 16:43:21 +00:00
..
protos feat(tvix): drop usage of sparseTree in favor of lib.sourceByRegex 2024-08-19 16:56:19 +00:00
src feat(tvix-store): Improve tvix-store copy. 2024-11-12 16:43:21 +00:00
build.rs chore(tvix): bump crate dependencies 2024-10-12 12:13:55 +00:00
Cargo.toml refactor(tvix/[ca]store): rename store composition feature flags 2024-11-11 18:46:33 +00:00
default.nix refactor(tvix/[ca]store): rename store composition feature flags 2024-11-11 18:46:33 +00:00
README.md fix(tvix/store): rename Read method in Readme 2023-09-26 15:24:32 +00:00

//tvix/store

This contains the code hosting the tvix-store.

For the local store, Nix realizes files on the filesystem in /nix/store (and maintains some metadata in a SQLite database). For "remote stores", it communicates this metadata in NAR (Nix ARchive) and NARInfo format.

Compared to the Nix model, tvix-store stores data on a much more granular level than that, which provides more deduplication possibilities, and more granular copying.

However, enough information is preserved to still be able to render NAR and NARInfo when needed.

More Information

The store consists out of two different gRPC services, tvix.castore.v1 for the low-level content-addressed bits, and tvix.store.v1 for the Nix and StorePath-specific bits.

Check the protos/ subfolder both here and in castore for the definition of the exact RPC methods and messages.

Interacting with the GRPC service manually

The shell environment in //tvix provides evans, which is an interactive REPL-based gPRC client.

You can use it to connect to a tvix-store and call the various RPC methods.

$ cargo run -- daemon &
$ evans --host localhost --port 8000 -r repl
  ______
 |  ____|
 | |__    __   __   __ _   _ __    ___
 |  __|   \ \ / /  / _. | | '_ \  / __|
 | |____   \ V /  | (_| | | | | | \__ \
 |______|   \_/    \__,_| |_| |_| |___/

 more expressive universal gRPC client


localhost:8000> package tvix.castore.v1
tvix.castore.v1@localhost:8000> service BlobService

tvix.castore.v1.BlobService@localhost:8000> call Put --bytes-from-file
data (TYPE_BYTES) => /run/current-system/system
{
  "digest": "KOM3/IHEx7YfInAnlJpAElYezq0Sxn9fRz7xuClwNfA="
}

tvix.castore.v1.BlobService@localhost:8000> call Read --bytes-as-base64
digest (TYPE_BYTES) => KOM3/IHEx7YfInAnlJpAElYezq0Sxn9fRz7xuClwNfA=
{
  "data": "eDg2XzY0LWxpbnV4"
}

$ echo eDg2XzY0LWxpbnV4 | base64 -d
x86_64-linux

Thanks to tvix-store providing gRPC Server Reflection (with reflection feature), you don't need to point evans to the .proto files.