[SDK Request] Rust SDK

[netthier]

Hello, I'd like to request you to consider adding an official SDK for the Rust language.
The openapi-generator supports Rust and generally generates sane code (including async support if the reqwest client is chosen).

[liamwh]

+1. I heard Andres Aguiar mention on the 25th of October last year that a Rust SDK was on the way, but we're almost in April 2024 and still no signs. I want to use OpenFGA with Rust. So I have 2 questions:

1. Is there a recommended way forward whilst there still isn't an SDK available to use OpenFGA with Rust? Can I generate a gRPC client from a protobuf or something?
2. Is there a timeline for when the Rust SDK will be delivered? An official SDK helps sell the solution to stakeholders.

Love your work guys,

Liam

[netthier]

I'm currently successfully using OpenFGA via a tonic_build-generated client.

[liamwh]

I'm currently successfully using OpenFGA via a tonic_build-generated client.

That's awesome! Do you have a repo I could reference by any chance?

Though for the maintainers, of course it would still be better to have first-party support.

[netthier]

I don't have it uploaded publicly, and I'm unsure how to properly package that kind of library, but it's not too difficult to set up.
I cloned https://github.com/openfga/api and ran buf export . --output=../proto to generate a directory containing the protobuf definitions of OpenFGA and its dependencies.
I then created a Rust library with the newly created proto directory next to src, with this build.rs:

use prost_wkt_build::{FileDescriptorSet, Message};
use std::{env, io::Result, path::PathBuf};

fn main() -> Result<()> {
    let out = PathBuf::from(env::var("OUT_DIR").unwrap());
    let descriptor_file = out.join("descriptors.bin");
    tonic_build::configure()
        .build_server(false)
        .build_client(true)
        .type_attribute(".", "#[derive(serde::Serialize,serde::Deserialize)]")
        .extern_path(".google.protobuf.Timestamp", "::prost_wkt_types::Timestamp")
        .extern_path(".google.protobuf.Struct", "::prost_wkt_types::Struct")
        .extern_path(".google.protobuf.Value", "::prost_wkt_types::Value")
        .file_descriptor_set_path(&descriptor_file)
        .compile(
            &[
                "proto/openfga/v1/authzmodel.proto",
                "proto/openfga/v1/errors_ignore.proto",
                "proto/openfga/v1/openapi.proto",
                "proto/openfga/v1/openfga.proto",
                "proto/openfga/v1/openfga_service.proto",
            ],
            &["proto/"],
        )
        .unwrap();

    let descriptor_bytes = std::fs::read(descriptor_file).unwrap();
    let descriptor = FileDescriptorSet::decode(&descriptor_bytes[..]).unwrap();
    prost_wkt_build::add_serde(out, descriptor);

    Ok(())
}

and this src/lib.rs:

pub use prost_types;
pub use tonic;

include!(concat!(env!("OUT_DIR"), "/openfga.v1.rs"));

[liamwh]

Thanks for this! Would you mind sending me a gist including the cargo.toml also? I believe I've repeated your instructions but get plenty the following compilation errors:

error[E0277]: the trait bound `Assertions: serde::de::Deserialize<'_>` is not satisfied
    --> /home/liam/.cargo-target/debug/build/openfga-rs-4c66487b7d4aec1f/out/openfga.v1.rs:1900:102
     |
1900 | ...ost_wkt :: typetag ; # [typetag :: serde (name = "type.googleapis.com/openfga.v1.Assertions")] impl :: prost_wkt :: MessageSe...
     |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `serde::de::Deserialize
<'_>` is not implemented for `Assertions`
     |
     = help: the following other types implement trait `serde::de::Deserialize<'de>`:
               bool
               char
               isize
               i8
               i16
               i32
               i64
               i128
             and 144 others
note: required by a bound in `erased_serde::de::deserialize`
    --> /home/liam/.cargo/registry/src/index.crates.io-6f17d22bba15001f/erased-serde-0.4.4/src/de.rs:42:8
     |
40   | pub fn deserialize<'de, T>(deserializer: &mut dyn Deserializer<'de>) -> Result<T, Error>
     |        ----------- required by a bound in this function
41   | where
42   |     T: serde::Deserialize<'de>,
     |        ^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `deserialize`
     = note: this error originates in the attribute macro `typetag::serde` (in Nightly builds, run with -Z macro-backtrace for more info)

For more information about this error, try `rustc --explain E0277`.
error: could not compile `openfga-rs` (lib) due to 152 previous errors

[rhamzeh]

Thanks for knowledge sharing @netthier!

@liamwh for the record, we have the Rust SDK on our roadmap, but it's not anytime soon. We have some work to do to streamline the SDK Generator to bring in more consistency, and make generating and supporting newer SDKs even easier. We're making some headway there, but the bulk of the work in the generator is planned over the next 6 months, after which new SDKs will be unblocked and hopefully will be much easier to contribute and maintain.

[netthier]

@liamwh
Ah sorry, I dropped .type_attribute(".", "#[derive(serde::Serialize,serde::Deserialize)]") from the build configuration because I thought it was specific to my use case. Adding that should derive those traits on the OpenFGA types appropriately.
And for reference, my Cargo.toml contains the following deps (though I'm not sure if all of them are necessary for this, esp the last two non-build deps):

[dependencies]
tonic = "0.10"
prost = "0.12"
prost-types = "0.12"
prost-wkt = "0.5"
prost-wkt-types = "0.5"
serde = { version = "1", features = ["derive"] }
schemars = { version = "0.8", features = ["chrono"] }
chrono = { version = "0.4", features = ["serde"] }

[build-dependencies]
tonic-build = "0.10"
prost-wkt-build = "0.5"

EDIT: Just noticed the build.rs literally contains prost_wkt_build::add_serde at the end. This would explain the dependency on serde lol. I bet if you remove that line you can also remove the type attributes.

[liamwh]

Thanks @netthier! With this I was able to set up a public repo:

Repo: https://github.com/liamwh/openfga-rs/
Docs.rs: https://docs.rs/openfga-rs/latest/openfga_rs/

In my spare time I'll try using this and add docs to the README. Do you have any examples or pointers to help me get started? Or feel free to open a PR if you please!