health: expose client for (#471)

tonic-health/build.rs

@@ -1,7 +1,7 @@
 fn main() -> Result<(), Box<dyn std::error::Error>> {
     tonic_build::configure()
         .build_server(true)
-        .build_client(false)
+        .build_client(true)
         .format(false)
         .compile(&["proto/health.proto"], &["proto/"])?;
 

tonic-health/proto/health.proto

@@ -1,23 +1,63 @@
+// Copyright 2015 The gRPC Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// The canonical version of this proto can be found at
+// https://github.com/grpc/grpc-proto/blob/master/grpc/health/v1/health.proto
+
 syntax = "proto3";
 
 package grpc.health.v1;
 
+option csharp_namespace = "Grpc.Health.V1";
+option go_package = "google.golang.org/grpc/health/grpc_health_v1";
+option java_multiple_files = true;
+option java_outer_classname = "HealthProto";
+option java_package = "io.grpc.health.v1";
+
 message HealthCheckRequest {
-    string service = 1;
+  string service = 1;
 }
 
 message HealthCheckResponse {
-    enum ServingStatus {
-        UNKNOWN = 0;
-        SERVING = 1;
-        NOT_SERVING = 2;
-        SERVICE_UNKNOWN = 3;  // Used only by the Watch method.
-    }
-    ServingStatus status = 1;
+  enum ServingStatus {
+    UNKNOWN = 0;
+    SERVING = 1;
+    NOT_SERVING = 2;
+    SERVICE_UNKNOWN = 3;  // Used only by the Watch method.
+  }
+  ServingStatus status = 1;
 }
 
 service Health {
-    rpc Check(HealthCheckRequest) returns (HealthCheckResponse);
+  // If the requested service is unknown, the call will fail with status
+  // NOT_FOUND.
+  rpc Check(HealthCheckRequest) returns (HealthCheckResponse);
 
-    rpc Watch(HealthCheckRequest) returns (stream HealthCheckResponse);
+  // Performs a watch for the serving status of the requested service.
+  // The server will immediately send back a message indicating the current
+  // serving status.  It will then subsequently send a new message whenever
+  // the service's serving status changes.
+  //
+  // If the requested service is unknown when the call is received, the
+  // server will send a message setting the serving status to
+  // SERVICE_UNKNOWN but will *not* terminate the call.  If at some
+  // future point, the serving status of the service becomes known, the
+  // server will send a new message with the service's serving status.
+  //
+  // If the call terminates with status UNIMPLEMENTED, then clients
+  // should assume this method is not supported and should not retry the
+  // call.  If the call terminates with any other status (including OK),
+  // clients should retry the call with appropriate exponential backoff.
+  rpc Watch(HealthCheckRequest) returns (stream HealthCheckResponse);
 }

tonic-health/src/lib.rs

@@ -22,8 +22,10 @@
 
 use std::fmt::{Display, Formatter};
 
-mod proto {
+/// These are the generated types from our health check proto file.
+pub mod proto {
     #![allow(unreachable_pub)]
+    #![allow(missing_docs)]
     tonic::include_proto!("grpc.health.v1");
 }