Other: Single instance

internal/focus/client.go

@@ -6,7 +6,9 @@ import (
 	"net"
 	"time"
 
+	"github.com/Masterminds/semver/v3"
 	"github.com/ProtonMail/proton-bridge/v2/internal/focus/proto"
+	"github.com/sirupsen/logrus"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials/insecure"
 	"google.golang.org/protobuf/types/known/emptypb"
@@ -27,6 +29,12 @@ func TryRaise() bool {
 		return false
 	}
 
+	defer func() {
+		if err := cc.Close(); err != nil {
+			logrus.WithError(err).Warn("Failed to close focus connection")
+		}
+	}()
+
 	if _, err := proto.NewFocusClient(cc).Raise(ctx, &emptypb.Empty{}); err != nil {
 		return false
 	}
@@ -37,3 +45,37 @@ func TryRaise() bool {
 
 	return true
 }
+
+// TryRaise tries to raise the application by dialing the focus service.
+// It returns true if the service is running and the application was told to raise.
+func TryVersion() (*semver.Version, bool) {
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+	defer cancel()
+
+	cc, err := grpc.DialContext(
+		ctx,
+		net.JoinHostPort(Host, fmt.Sprint(Port)),
+		grpc.WithTransportCredentials(insecure.NewCredentials()),
+	)
+	if err != nil {
+		return nil, false
+	}
+
+	defer func() {
+		if err := cc.Close(); err != nil {
+			logrus.WithError(err).Warn("Failed to close focus connection")
+		}
+	}()
+
+	raw, err := proto.NewFocusClient(cc).Version(ctx, &emptypb.Empty{})
+	if err != nil {
+		return nil, false
+	}
+
+	version, err := semver.NewVersion(raw.GetVersion())
+	if err != nil {
+		return nil, false
+	}
+
+	return version, true
+}