[#1768] Add healthcheck method to the Tree service

Signed-off-by: Anton Nikiforov <an.nikiforov@yadro.com>

CHANGELOG.md

@@ -17,6 +17,7 @@ Changelog for NeoFS Node
 - `--timeout` flag in `neofs-cli` subcommands (#1837)
 - `container nodes` command to output list of nodes for container, grouped by replica (#1704)
 - Configuration flag to ignore shard in `neofs-node` (#1840)
+- Add new RPC `TreeService.Healthcheck`
 
 ### Changed
 - Allow to evacuate shard data with `EvacuateShard` control RPC (#1800)

pkg/services/tree/service.go

@@ -558,3 +558,7 @@ func (s *Service) getContainerInfo(cid cidSDK.ID, pub []byte) ([]netmapSDK.NodeI
 	}
 	return cntNodes, -1, len(cntNodes), nil
 }
+
+func (s *Service) Healthcheck(context.Context, *HealthcheckRequest) (*HealthcheckResponse, error) {
+	return new(HealthcheckResponse), nil
+}

pkg/services/tree/service.proto

@@ -47,6 +47,8 @@ service TreeService {
   rpc Apply (ApplyRequest) returns (ApplyResponse);
   // GetOpLog returns a stream of logged operations starting from some height.
   rpc GetOpLog(GetOpLogRequest) returns (stream GetOpLogResponse);
+  // Healthcheck is a dummy rpc to check service availability
+  rpc Healthcheck(HealthcheckRequest) returns (HealthcheckResponse);
 }
 
 message AddRequest {
@@ -328,3 +330,23 @@ message GetOpLogResponse {
   // Response signature.
   Signature signature = 2;
 };
+
+message HealthcheckResponse {
+  message Body {
+  }
+
+  // Response body.
+  Body body = 1;
+  // Response signature.
+  Signature signature = 2;
+};
+
+message HealthcheckRequest {
+  message Body {
+  }
+
+  // Request body.
+  Body body = 1;
+  // Request signature.
+  Signature signature = 2;
+}