Add tls example with rustls

tonic-examples/src/tls/client.rs

@@ -0,0 +1,28 @@
+pub mod pb {
+    include!(concat!(env!("OUT_DIR"), "/grpc.examples.echo.rs"));
+}
+
+use pb::{client::EchoClient, EchoRequest};
+use tonic::transport::{Certificate, Channel};
+
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let pem = tokio::fs::read("tonic-examples/data/tls/ca.pem").await?;
+    let ca = Certificate::from_pem(pem);
+
+    let channel = Channel::from_static("http://[::1]:50051")
+        .rustls_tls(ca, Some("example.com".into()))
+        .channel();
+
+    let mut client = EchoClient::new(channel);
+
+    let request = tonic::Request::new(EchoRequest {
+        message: "hello".into(),
+    });
+
+    let response = client.unary_echo(request).await?;
+
+    println!("RESPONSE={:?}", response);
+
+    Ok(())
+}