[#306] Define and compile proto files for private node service

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

Makefile

@@ -66,7 +66,7 @@ protoc:
 	@for f in `find . -type f -name '*.proto' -not -path './vendor/*'`; do \
 		echo "⇒ Processing $$f "; \
 		protoc \
-			--proto_path=.:./vendor:./vendor/github.com/nspcc-dev/neofs-api-go:/usr/local/include \
+			--proto_path=.:./vendor:./vendor/github.com/nspcc-dev/neofs-api-go:/usr/local/include:./pkg/services/private \
 			--gofast_out=plugins=grpc,paths=source_relative:. $$f; \
 	done
 	rm -rf vendor

go.mod

@@ -5,6 +5,7 @@ go 1.14
 require (
 	code.cloudfoundry.org/bytefmt v0.0.0-20200131002437-cf55d5288a48
 	github.com/alecthomas/participle v0.6.0
+	github.com/golang/protobuf v1.4.3
 	github.com/google/uuid v1.1.1
 	github.com/hashicorp/golang-lru v0.5.4
 	github.com/klauspost/compress v1.11.3

pkg/services/private/service.proto

@@ -0,0 +1,41 @@
+syntax = "proto3";
+
+package private;
+
+import "types.proto";
+
+option go_package = "github.com/nspcc-dev/neofs-node/pkg/services/private";
+
+// `PrivateService` provides an interface for internal work with the storage node.
+service PrivateService {
+    // Performs health check of the storage node.
+    rpc HealthCheck (HealthCheckRequest) returns (HealthCheckResponse);
+}
+
+// Health check request.
+message HealthCheckRequest {
+    // Health check request body.
+    message Body {
+    }
+
+    // Body of health check request message.
+    Body body = 1;
+
+    // Body signature.
+    Signature signature = 2;
+}
+
+// Health check request.
+message HealthCheckResponse {
+    // Health check response body
+    message Body {
+        // Health status of storage node.
+        HealthStatus status = 1;
+    }
+
+    // Body of health check response message.
+    Body body = 1;
+
+    // Body signature.
+    Signature signature = 2;
+}

pkg/services/private/types.proto

@@ -0,0 +1,26 @@
+syntax = "proto3";
+
+package private;
+
+option go_package = "github.com/nspcc-dev/neofs-node/pkg/services/private";
+
+// Signature of some message.
+message Signature {
+    // Public key used for signing.
+    bytes key = 1 [json_name = "key"];
+
+    // Binary signature.
+    bytes sign = 2 [json_name = "signature"];
+}
+
+// Health status of the storage node.
+enum HealthStatus {
+    // Undefined status, default value.
+    STATUS_UNDEFINED = 0;
+
+    // Node is online.
+    ONLINE = 1;
+
+    // Node is offline.
+    OFFLINE = 2;
+}