feat(otlp): Re-export tonic crate

opentelemetry-otlp/allowed-external-types.toml

@@ -16,6 +16,9 @@ allowed_external_types = [
     "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};
+    }
+}