Remove the option of using grpcio for gRPC (#1534)

Author: djc

.github/workflows/ci.yml

@@ -70,7 +70,7 @@ jobs:
   non-default-examples:
     strategy:
       matrix:
-        example: [opentelemetry-otlp/examples/external-otlp-grpcio-async-std, opentelemetry-otlp/examples/basic-otlp]
+        example: [opentelemetry-otlp/examples/basic-otlp]
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v1

Cargo.toml

@@ -17,7 +17,6 @@ members = [
     "opentelemetry-zipkin",
     "opentelemetry-otlp/examples/basic-otlp",
     "opentelemetry-otlp/examples/basic-otlp-http",
-    "opentelemetry-otlp/examples/external-otlp-grpcio-async-std",
     "opentelemetry-otlp/tests/integration_test",
     "examples/metrics-basic",
     "examples/metrics-advanced",
@@ -43,7 +42,6 @@ env_logger = "0.10"
 futures-core = "0.3"
 futures-executor = "0.3"
 futures-util = "0.3"
-grpcio = "0.12"
 hyper = "0.14"
 http = "0.2"
 isahc = "1.4"

opentelemetry-otlp/CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## vNext
 
+- Remove support for grpcio transport (#1534)
+
 ## v0.14.0
 
 ### Added

opentelemetry-otlp/Cargo.toml

@@ -28,7 +28,6 @@ rustdoc-args = ["--cfg", "docsrs"]
 [dependencies]
 async-trait = { workspace = true }
 futures-core = { workspace = true }
-grpcio = { workspace = true, optional = true }
 opentelemetry = { version = "0.21", default-features = false, path = "../opentelemetry" }
 opentelemetry_sdk = { version = "0.21", default-features = false, path = "../opentelemetry-sdk" }
 opentelemetry-http = { version = "0.10", path = "../opentelemetry-http", optional = true }
@@ -71,11 +70,6 @@ gzip-tonic = ["tonic/gzip"]
 tls = ["tonic/tls"]
 tls-roots = ["tls", "tonic/tls-roots"]
 
-# grpc using grpcio
-grpc-sys = ["grpcio", "opentelemetry-proto/gen-grpcio"]
-openssl = ["grpcio/openssl"]
-openssl-vendored = ["grpcio/openssl-vendored"]
-
 # http binary
 http-proto = ["prost", "opentelemetry-http", "opentelemetry-proto/gen-tonic-messages", "http", "trace", "metrics"]
 reqwest-blocking-client = ["reqwest/blocking", "opentelemetry-http/reqwest"]

opentelemetry-otlp/README.md

@@ -46,7 +46,6 @@ use opentelemetry::trace::Tracer;
 
 fn main() -> Result<(), Box<dyn std::error::Error + Send + Sync + 'static>> {
     // use tonic as grpc layer here.
-    // If you want to use grpcio. enable `grpc-sys` feature and use with_grpcio function here.
     let tracer = opentelemetry_otlp::new_pipeline()
       .tracing()
       .with_exporter(opentelemetry_otlp::new_exporter().tonic())
@@ -71,7 +70,7 @@ automatically.
 ```toml
 [dependencies]
 opentelemetry_sdk = { version = "*", features = ["async-std"] }
-opentelemetry-otlp = { version = "*", features = ["grpc-sys"] }
+opentelemetry-otlp = { version = "*", features = ["grpc-tonic"] }
 ```
 
 ```rust
@@ -84,26 +83,11 @@ let tracer = opentelemetry_otlp::new_pipeline()
 
 ## Kitchen Sink Full Configuration
 
-[Example](https://docs.rs/opentelemetry-otlp/latest/opentelemetry_otlp/#kitchen-sink-full-configuration) 
+[Example](https://docs.rs/opentelemetry-otlp/latest/opentelemetry_otlp/#kitchen-sink-full-configuration)
 showing how to override all configuration options.
 
-Generally there are two parts of configuration. One is metrics config 
+Generally there are two parts of configuration. One is metrics config
 or tracing config. Users can config it via [`OtlpTracePipeline`]
 or [`OtlpMetricPipeline`]. The other is exporting configuration.
 Users can set those configurations using [`OtlpExporterPipeline`] based
 on the choice of exporters.
-
-# Grpc libraries comparison
-
-Multiple gRPC transport layers are available. [`tonic`](https://crates.io/crates/tonic) is the default gRPC transport
-layer and is enabled by default. [`grpcio`](https://crates.io/crates/grpcio) is optional.
-
-| gRPC transport layer | [hyperium/tonic](https://github.com/hyperium/tonic) | [tikv/grpc-rs](https://github.com/tikv/grpc-rs) |
-|---|---|---|
-| Feature | --features=default | --features=grpc-sys |
-| gRPC library | [`tonic`](https://crates.io/crates/tonic) | [`grpcio`](https://crates.io/crates/grpcio) |
-| Transport | [hyperium/hyper](https://github.com/hyperium/hyper) (Rust) | [grpc/grpc](https://github.com/grpc/grpc) (C++ binding) |
-| TLS support | yes | yes |
-| TLS library | rustls | OpenSSL |
-| TLS optional | yes | yes |
-| Supported .proto generator | [`prost`](https://crates.io/crates/prost) | [`prost`](https://crates.io/crates/prost), [`protobuf`](https://crates.io/crates/protobuf) |