[#552] Add sdnotify package

To avoid using third-party dependencies.

Signed-off-by: Ekaterina Lebedeva <ekaterina.lebedeva@yadro.com>

cmd/frostfs-node/control.go

@@ -10,8 +10,8 @@ import (
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/control"
 	controlSvc "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/control/server"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/tree"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util/sdnotify"
 	cid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
-	sysdnotify "github.com/iguanesolutions/go-systemd/v5/notify"
 	"go.uber.org/zap"
 	"google.golang.org/grpc"
 )
@@ -109,14 +109,13 @@ func (c *cfg) HealthStatus() control.HealthStatus {
 	return control.HealthStatus(c.healthStatus.Load())
 }
 
-func (c *cfg) notifySystemd(st control.HealthStatus) string {
+func (c *cfg) notifySystemd(st control.HealthStatus) {
 	status := fmt.Sprintf("%v, %v", st.Number(), st)
-	err := sysdnotify.Status(status)
+	err := sdnotify.Status(status)
 	if err == nil {
 		c.log.Info(fmt.Sprintf("reported STATUS=\"%v\" to systemd", status))
 	}
 	if err != nil {
 		c.log.Error(logs.FailedToReportStatusToSystemd, zap.String("error", err.Error()))
 	}
-	return fmt.Sprintf("%v, %v", st, control.HealthStatus_name[int32(st)])
 }

go.mod

@@ -16,7 +16,6 @@ require (
 	github.com/flynn-archive/go-shlex v0.0.0-20150515145356-3f9db97f8568
 	github.com/google/uuid v1.4.0
 	github.com/hashicorp/golang-lru/v2 v2.0.7
-	github.com/iguanesolutions/go-systemd/v5 v5.1.1
 	github.com/klauspost/compress v1.17.4
 	github.com/mitchellh/go-homedir v1.1.0
 	github.com/mr-tron/base58 v1.2.0

pkg/util/sdnotify/sdnotify.go

@@ -0,0 +1,59 @@
+package sdnotify
+
+import (
+	"fmt"
+	"net"
+	"os"
+	"strings"
+)
+
+const (
+	ReadyEnabled     = "READY=1"
+	StoppingEnabled  = "STOPPING=1"
+	ReloadingEnabled = "RELOADING=1"
+)
+
+var socket *net.UnixAddr
+
+// Initializes socket with provided name of
+// environment variable.
+func InitSocket() error {
+	notifySocket := os.Getenv("NOTIFY_SOCKET")
+	if notifySocket == "" {
+		return fmt.Errorf("\"NOTIFY_SOCKET\" environment variable is not present")
+	}
+	socket = &net.UnixAddr{
+		Name: notifySocket,
+		Net:  "unixgram",
+	}
+	return nil
+}
+
+// FlagAndStatus sends systemd a combination of a
+// well-known status and STATUS=%s{status}, separated by newline.
+func FlagAndStatus(status string) error {
+	status += "\nSTATUS=" + strings.TrimSuffix(status, "=1")
+	return Send(status)
+}
+
+// Status sends systemd notify STATUS=%s{status}.
+func Status(status string) error {
+	return Send(fmt.Sprintf("STATUS=%s", status))
+}
+
+// Send state through the notify socket if any.
+// If the notify socket was not detected, it returns an error.
+func Send(state string) error {
+	if socket == nil {
+		return fmt.Errorf("socket is not initialized")
+	}
+	conn, err := net.DialUnix(socket.Net, nil, socket)
+	if err != nil {
+		return fmt.Errorf("can't open unix socket: %v", err)
+	}
+	defer conn.Close()
+	if _, err = conn.Write([]byte(state)); err != nil {
+		return fmt.Errorf("can't write into the unix socket: %v", err)
+	}
+	return nil
+}