Reflection service - using dynamic file descriptor sets

[dado0583]

I've added tonic_reflection 0.6 to my Cargo.toml and added the reflection service, but it looks like I need to load the file descriptor set from the tonic_build output. I don't have that to hand.

Some context:

• I have a multi language implementation of models and client code in one repo (here)
• The auto-generated code gets deployed as a crate called ledger-models here.

I am now writing code in a private repo (broker-service), and need to add the reflection service:

    let service = tonic_reflection::server::Builder::configure()
        .register_encoded_file_descriptor_set(proto::FILE_DESCRIPTOR_SET)
        .build()
        .unwrap();

I don't currently build the file descriptor set via include_file_descriptor_set. Do I "have" to do that, and ship with my ledger-models crate?

I'd prefer to do it dynamically if possible from the Rust-generated files. E.g. the service rust file or request rust file.

Any pointers as to whether I must ship the file descriptor set from the tonic_build, or is there a way to do this dynamically?

Thanks in advance for any help!

[LucioFranco]

I think you want to use https://docs.rs/tonic-build/latest/tonic_build/struct.Builder.html#method.file_descriptor_set_path in the repo that contains the protobuf files and embed the fds into that code. I think you can use include_bytes cuz iirc its not actual rust code. This will then ship it with that code and it should be either writable to disk or passable to the reflection code.

[dado0583]

The challenge I had with that is the ledger models crate defines service definitions for about 8 services.

Multiple codebases import that crate so they know what to implement and how to communicate to other services. But they may expose only one service definition.

Using tonic_reflection it by default exposes all the service definitions so for now I copied the code and added a filter functionality.

Or put in pseudo code:

• service A project imports ledger-models
• service A loads the file descriptor from there
• it pushes it into the reflection service (modified version)
• reflection service exposes only a subset of services via reflection (modified version)

I'm going to see if I can filter the file descriptor set before loading the bytes into the reflection service but this modified version works fine.