GRPC.Stub generated in gprc_server only project

[Steven0351]

Describe the bug
the protoc plugin for grpc_server generates a GRPC.Stub. GRPC.Stub is in grpc, which means I need to either delete the code after generation, or depend on grpc as well.

To Reproduce
Create a simple proto definition:

// test.proto

syntax = "proto3";

package myapp.test;

message SubmitRequest {
  string id = 1;
}

message SubmitResponse {
  string message = 1;
}

service TestServer {
  rpc Submit (SubmitRequest) returns (SubmitResponse) {}
}

run the generator: protoc --elixir_out=plugins=grpc:./ test.proto

observe the output:

defmodule Myapp.Test.SubmitRequest do
  @moduledoc false

  use Protobuf,
    full_name: "myapp.test.SubmitRequest",
    protoc_gen_elixir_version: "0.16.0",
    syntax: :proto3

  field :id, 1, type: :string
end

defmodule Myapp.Test.SubmitResponse do
  @moduledoc false

  use Protobuf,
    full_name: "myapp.test.SubmitResponse",
    protoc_gen_elixir_version: "0.16.0",
    syntax: :proto3

  field :message, 1, type: :string
end

defmodule Myapp.Test.TestServer.Service do
  @moduledoc false

  use GRPC.Service, name: "myapp.test.TestServer", protoc_gen_elixir_version: "0.16.0"

  rpc :Submit, Myapp.Test.SubmitRequest, Myapp.Test.SubmitResponse
end

defmodule Myapp.Test.TestServer.Stub do
  @moduledoc false

  use GRPC.Stub, service: Myapp.Test.TestServer.Service
end

Expected behavior
I would expect that server-only projects would not have client code generated. Otherwise, I would expect that grpc_server would depend on grpc if this behavior is intended.

Versions:

• OS: NixOS 26.05
• Erlang: OTP 28
• Elixir: 1.19.5
• mix.lock(grpc, gun, cowboy, cowlib):

%{
  "cowboy": {:hex, :cowboy, "2.16.1", "fa04080b602ff25c40a7700f2dc0152dbc1ba26b42093ae0fa9bb7a337d5a242", [:make, :rebar3], [{:cowlib, ">= 2.16.0 and < 3.0.0", [hex: :cowlib, repo: "hexpm", optional: false]}, {:ranch, ">= 1.8.0 and < 3.0.0", [hex: :ranch, repo: "hexpm", optional: false]}], "hexpm", "b8ea4dd317a043e3177ec840cfa3bcb47cfb41035d3abb24d954dc7d51def399"},
  "cowlib": {:hex, :cowlib, "2.17.1", "3e6053016d1ab245730f0af688755476dcedb1c25ed8fb5751f59a2bfdc0c9af", [:make, :rebar3], [], "hexpm", "ff08bd17e6dd931445b18af77315b9b5fe052407110964ad2588c686b57b5e3f"},
  "flow": {:hex, :flow, "1.2.4", "1dd58918287eb286656008777cb32714b5123d3855956f29aa141ebae456922d", [:mix], [{:gen_stage, "~> 1.0", [hex: :gen_stage, repo: "hexpm", optional: false]}], "hexpm", "874adde96368e71870f3510b91e35bc31652291858c86c0e75359cbdd35eb211"},
  "gen_stage": {:hex, :gen_stage, "1.3.2", "7c77e5d1e97de2c6c2f78f306f463bca64bf2f4c3cdd606affc0100b89743b7b", [:mix], [], "hexpm", "0ffae547fa777b3ed889a6b9e1e64566217413d018cabd825f786e843ffe63e7"},
  "googleapis": {:hex, :googleapis, "0.1.0", "13770f3f75f5b863fb9acf41633c7bc71bad788f3f553b66481a096d083ee20e", [:mix], [{:protobuf, "~> 0.12", [hex: :protobuf, repo: "hexpm", optional: false]}], "hexpm", "1989a7244fd17d3eb5f3de311a022b656c3736b39740db46506157c4604bd212"},
  "grpc_core": {:hex, :grpc_core, "1.0.1", "7484d6f016fa9956bac57a164473e651683bbb735a056c0e89db54d04c776266", [:mix], [{:googleapis, "~> 0.1.0", [hex: :googleapis, repo: "hexpm", optional: false]}, {:jason, ">= 0.0.0", [hex: :jason, repo: "hexpm", optional: false]}, {:protobuf, "~> 0.17", [hex: :protobuf, repo: "hexpm", optional: false]}, {:telemetry, "~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "caebb9c12bd963b1a7750ced1b95feebcec9a7b78f5c1ee8d6fab3f6ff288822"},
  "grpc_server": {:hex, :grpc_server, "1.0.1", "9ecdeee528c975d5c7704cf9671c46681d4a9fcb939da95cb0d4e977398ff5a2", [:mix], [{:cowboy, "~> 2.14", [hex: :cowboy, repo: "hexpm", optional: false]}, {:cowlib, "~> 2.14", [hex: :cowlib, repo: "hexpm", optional: false]}, {:flow, "~> 1.2", [hex: :flow, repo: "hexpm", optional: false]}, {:grpc_core, "~> 1.0.1", [hex: :grpc_core, repo: "hexpm", optional: false]}, {:protobuf, "~> 0.17", [hex: :protobuf, repo: "hexpm", optional: false]}], "hexpm", "6f1c61049264e2f51fdc408652b766b40ab642a3029888b53b6be087e89106cd"},
  "hpax": {:hex, :hpax, "1.0.3", "ed67ef51ad4df91e75cc6a1494f851850c0bd98ebc0be6e81b026e765ee535aa", [:mix], [], "hexpm", "8eab6e1cfa8d5918c2ce4ba43588e894af35dbd8e91e6e55c817bca5847df34a"},
  "jason": {:hex, :jason, "1.4.5", "2e3a008590b0b8d7388c20293e9dcc9cf3e5d642fd2a114e4cbbb52e595d940a", [:mix], [{:decimal, "~> 1.0 or ~> 2.0 or ~> 3.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm", "b0c823996102bcd0239b3c2444eb00409b72f6a140c1950bc8b457d836b30684"},
  "mint": {:hex, :mint, "1.9.0", "d6f534c2a3e98b2a8cc749b4796eb77e9e3af79a76f96e4c74035a827de0d318", [:mix], [{:castore, "~> 0.1.0 or ~> 1.0", [hex: :castore, repo: "hexpm", optional: true]}, {:hpax, "~> 0.1.1 or ~> 0.2.0 or ~> 1.0", [hex: :hpax, repo: "hexpm", optional: false]}], "hexpm", "007154c7d8c43916aed3c93afd1f11aebbaa9c5ff4b7ba55ebe0d17ee0296042"},
  "mint_web_socket": {:hex, :mint_web_socket, "1.0.5", "60354efeb49b1eccf95dfb75f55b08d692e211970fe735a5eb3188b328be2a90", [:mix], [{:mint, ">= 1.4.1 and < 2.0.0-0", [hex: :mint, repo: "hexpm", optional: false]}], "hexpm", "04b35663448fc758f3356cce4d6ac067ca418bbafe6972a3805df984b5f12e61"},
  "protobuf": {:hex, :protobuf, "0.17.0", "39e24e43c9648e148feba16ed51100b5b2028ea900b55460377b0476f6e10613", [:mix], [{:jason, "~> 1.2", [hex: :jason, repo: "hexpm", optional: true]}], "hexpm", "ca6c91f6f63e2c147b47f03eefd10b80538aa6fc55ff4b12b795efb786b0152f"},
  "ranch": {:hex, :ranch, "2.2.0", "25528f82bc8d7c6152c57666ca99ec716510fe0925cb188172f41ce93117b1b0", [:make, :rebar3], [], "hexpm", "fa0b99a1780c80218a4197a59ea8d3bdae32fbff7e88527d7d8a4787eff4f8e7"},
}

[sleipnir]

Hello @Steven0351, thanks for opening the issue. However, I believe this is related to the protobuf library, as it is responsible for generating the stubs.

[Steven0351]

Hello @Steven0351, thanks for opening the issue. However, I believe this is related to the protobuf library, as it is responsible for generating the stubs.

Is this not the template responsible? https://github.com/elixir-grpc/grpc/blob/master/grpc_server/priv/templates/service.ex.eex

[sleipnir]

Yes, the Stub—indeed.
But why do you say the server depends on the client? The fact that the Stub was generated doesn't mean there is a dependency between the hex packages. As far as I recall, there is no such dependency on the server side. I need to refresh my memory and take a closer look, but I think they are separate things.

[Steven0351]

Yes, the Stub—indeed. But why do you say the server depends on the client? The fact that the Stub was generated doesn't mean there is a dependency between the hex packages. As far as I recall, there is no such dependency on the server side. I need to refresh my memory and take a closer look, but I think they are separate things.

The code that is generated by the grpc plugin does not compile because GRPC.Stub is implemented in grpc, not grpc_server. So, after generating the code, I then have to go delete the stub.

[sleipnir]

Actually, I just checked and the protoc hooks is on the server. We would need to split this up or move it to the core. I'll look into it and get back to you once I better understand the impact of making changes here.