Remove the option of using grpcio for gRPC

Author: djc

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/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"]