feat(otlp): Re-export tonic crate

.github/workflows/ci.yml

@@ -102,7 +102,7 @@ jobs:
         run: |
           cargo install [email protected]
           cd ${{ matrix.example }}
-          cargo check-external-types --config allowed-external-types.toml
+          cargo check-external-types --all-features --config allowed-external-types.toml
   msrv:
     strategy:
       matrix:

opentelemetry-otlp/allowed-external-types.toml

@@ -3,20 +3,16 @@
 # This is used with cargo-check-external-types to reduce the surface area of downstream crates from
 # the public API. Ideally this can have a few exceptions as possible.
 allowed_external_types = [
-    "opentelemetry::*",
     "opentelemetry_http::*",
     "opentelemetry_sdk::*",
-    # http is a pre 1.0 crate
-    "http::uri::InvalidUri",
-    "http::header::name::InvalidHeaderName",
-    "http::header::value::InvalidHeaderValue",
-    # prost is a pre 1.0 crate
-    "prost::error::EncodeError",
+    # serde
+    "serde::de::Deserialize",
+    "serde::ser::Serialize",
     # tonic is a pre 1.0 crate
-    "tonic::status::Code",
-    "tonic::status::Status",
     "tonic::metadata::map::MetadataMap",
+    "tonic::transport::channel::tls::ClientTlsConfig",
+    "tonic::transport::tls::Certificate",
+    "tonic::transport::tls::Identity",
     "tonic::transport::channel::Channel",
-    "tonic::transport::error::Error",
     "tonic::service::interceptor::Interceptor",
 ]

opentelemetry-otlp/src/lib.rs

@@ -450,3 +450,20 @@ pub enum Protocol {
 #[doc(hidden)]
 /// Placeholder type when no exporter pipeline has been configured in telemetry pipeline.
 pub struct NoExporterConfig(());
+
+/// Re-exported types from the `tonic` crate.
+#[cfg(feature = "grpc-tonic")]
+pub mod tonic_types {
+    /// Re-exported types from `tonic::metadata`.
+    pub mod metadata {
+        #[doc(no_inline)]
+        pub use tonic::metadata::MetadataMap;
+    }
+
+    /// Re-exported types from `tonic::transport`.
+    #[cfg(feature = "tls")]
+    pub mod transport {
+        #[doc(no_inline)]
+        pub use tonic::transport::{Certificate, ClientTlsConfig, Identity};
+    }
+}