History

Florian Klink c4ee942b1c feat(tvix/store/protos): rename Get to Read, add Stat method Stat exposes metadata about a given blob, such as more granular chunking, baos. It implicitly allows checking for existence too, as asking this for a non-existing Blob will return a Status::not_found grpc error. The previous version returned a Status::not_found error on the Get request too, but there was no chance to prevent the server from starting to stream (except sending an immediate cancellation). Being able to check whether something exists in a BlobStore helps to prevent from uploading in first place. The granular chunking bits are an optional optimization - if the BlobStore implements no more granular chunking, the Stat response can simply contain a single chunk. Read returns a stream of BlobChunk, which is just a stream of bytes - not necessarily using the chunking that's returned in the reply of a Stat() call. It can be used to read blobs or chunks. Change-Id: I4b6030ef184ace5484c84ca273b49d710433731d Reviewed-on: https://cl.tvl.fyi/c/depot/+/7652 Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI		2022-12-28 13:55:18 +00:00
..
docs	docs(tvix/store): add README, document services and store model	2022-12-26 11:38:52 +00:00
protos	feat(tvix/store/protos): rename Get to Read, add Stat method	2022-12-28 13:55:18 +00:00
src	feat(tvix/store): implement Directory::validate()	2022-12-28 10:58:50 +00:00
build.rs	feat(tvix/store): use tonic-build for protos	2022-12-26 11:38:52 +00:00
Cargo.toml	feat(tvix/store): implement Directory::validate()	2022-12-28 10:58:50 +00:00
default.nix	feat(tvix/proto): add rpc_directory.proto	2022-12-22 14:35:32 +00:00
README.md	docs(tvix/store): add README, document services and store model	2022-12-26 11:38:52 +00:00

README.md

//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 (handled by //tvix/nar-bridge).

More Information

Check the protos/ subfolder 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 &
$ evans --host localhost --port 8000 -r repl
  ______
 |  ____|
 | |__    __   __   __ _   _ __    ___
 |  __|   \ \ / /  / _. | | '_ \  / __|
 | |____   \ V /  | (_| | | | | | \__ \
 |______|   \_/    \__,_| |_| |_| |___/

 more expressive universal gRPC client


tvix.store.v1@localhost:8000> service BlobService

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

tvix.store.v1.BlobService@localhost:8000> call Get --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.