[#306] private: Define and use HealthChecker interface to get the status

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

pkg/services/private/server/healthcheck.go

@@ -23,8 +23,7 @@ func (s *Server) HealthCheck(_ context.Context, req *private.HealthCheckRequest)
 	body := new(private.HealthCheckResponse_Body)
 	resp.SetBody(body)
 
-	// FIXME: calculate the status
-	body.SetStatus(private.HealthStatus_ONLINE)
+	body.SetStatus(s.healthChecker.HealthStatus())
 
 	// sign the response
 	if err := SignMessage(s.key, resp); err != nil {

pkg/services/private/server/server.go

@@ -2,6 +2,8 @@ package private
 
 import (
 	"crypto/ecdsa"
+
+	"github.com/nspcc-dev/neofs-node/pkg/services/private"
 )
 
 // Server is an entity that serves
@@ -10,6 +12,16 @@ type Server struct {
 	*cfg
 }
 
+// HealthChecker is component interface for calculating
+// the current health status of a node.
+type HealthChecker interface {
+	// Must calculate and return current node health status.
+	//
+	// If status can not be calculated for any reason,
+	// private.HealthStatus_STATUS_UNDEFINED should be returned.
+	HealthStatus() private.HealthStatus
+}
+
 // Option of the Server's constructor.
 type Option func(*cfg)
 
@@ -17,6 +29,8 @@ type cfg struct {
 	key *ecdsa.PrivateKey
 
 	allowedKeys [][]byte
+
+	healthChecker HealthChecker
 }
 
 func defaultCfg() *cfg {
@@ -51,3 +65,11 @@ func WithAllowedKeys(keys [][]byte) Option {
 		c.allowedKeys = append(c.allowedKeys, keys...)
 	}
 }
+
+// WithHealthChecker returns option to set component
+// to calculate node health status.
+func WithHealthChecker(hc HealthChecker) Option {
+	return func(c *cfg) {
+		c.healthChecker = hc
+	}
+}