fix(proxy): use local SPDK client for engine lookup in v2 VolumeGet

The v2 proxy VolumeGet handler previously used req.Address (the
DirectToURL of the service object) to create an SPDK client for both
engine and EngineFrontend lookups. For v2 volumes, the manager passes
the EngineFrontend's IM address as req.Address so the proxy can observe
the frontend device state.

When engine and EngineFrontend are on different Instance Managers (e.g.
after fault recovery), this causes the handler to look up the engine on
the EF's IM where it does not exist, resulting in a permanent NotFound
error.

Fix this by separating the two lookups:
- Engine: always use the local SPDK service (the proxy runs on the
  engine's IM, so the engine is guaranteed to be local)
- EngineFrontend: use req.Address to reach the potentially remote EF IM

If the EF client connection fails, gracefully degrade to engine-only
info rather than failing the entire call.

Longhorn 13215

Signed-off-by: Derek Su <derek.su@suse.com>

Author: derekbit

pkg/proxy/proxy.go

@@ -60,7 +60,9 @@ type ProxyOps interface {
 }
 
 type V1DataEngineProxyOps struct{}
-type V2DataEngineProxyOps struct{}
+type V2DataEngineProxyOps struct {
+	spdkServiceAddress string
+}
 
 type Proxy struct {
 	rpc.UnimplementedProxyEngineServiceServer
@@ -77,7 +79,7 @@ func NewProxy(ctx context.Context, logsDir, diskServiceAddress, spdkServiceAddre
 
 	ops := map[rpc.DataEngine]ProxyOps{
 		rpc.DataEngine_DATA_ENGINE_V1: V1DataEngineProxyOps{},
-		rpc.DataEngine_DATA_ENGINE_V2: V2DataEngineProxyOps{},
+		rpc.DataEngine_DATA_ENGINE_V2: V2DataEngineProxyOps{spdkServiceAddress: spdkServiceAddress},
 	}
 
 	spdkLocalClient, err := spdkclient.NewSPDKClient(spdkServiceAddress)

pkg/proxy/volume.go

@@ -16,6 +16,7 @@ import (
 	lhns "github.com/longhorn/go-common-libs/ns"
 	lhtypes "github.com/longhorn/go-common-libs/types"
 	eclient "github.com/longhorn/longhorn-engine/pkg/controller/client"
+	spdkclient "github.com/longhorn/longhorn-spdk-engine/pkg/client"
 	rpc "github.com/longhorn/types/pkg/generated/imrpc"
 
 	"github.com/longhorn/longhorn-instance-manager/pkg/util"
@@ -77,22 +78,26 @@ func (ops V1DataEngineProxyOps) VolumeGet(ctx context.Context, req *rpc.ProxyEng
 }
 
 func (ops V2DataEngineProxyOps) VolumeGet(ctx context.Context, req *rpc.ProxyEngineRequest) (resp *rpc.EngineVolumeGetProxyResponse, err error) {
-	c, err := getSPDKClientFromAddress(req.Address)
+	// The engine is always local to this IM (proxy runs on engine IM).
+	// Use the local SPDK service for EngineGet so it works even when the
+	// EngineFrontend is on a remote node.
+	localClient, err := spdkclient.NewSPDKClient(ops.spdkServiceAddress)
 	if err != nil {
-		return nil, grpcstatus.Errorf(grpccodes.Internal, "failed to get SPDK client from engine address %v: %v", req.Address, err)
+		return nil, grpcstatus.Errorf(grpccodes.Internal, "failed to create local SPDK client for address %v: %v", ops.spdkServiceAddress, err)
 	}
 	defer func() {
-		if closeErr := c.Close(); closeErr != nil {
+		if closeErr := localClient.Close(); closeErr != nil {
 			logrus.WithFields(logrus.Fields{
 				"serviceURL":         req.Address,
-				"engineFrontendName": req.EngineFrontendName,
+				"spdkServiceAddress": ops.spdkServiceAddress,
+				"engineName":         req.EngineName,
 				"volumeName":         req.VolumeName,
 				"dataEngine":         req.DataEngine,
-			}).WithError(closeErr).Warn("Failed to close SPDK client")
+			}).WithError(closeErr).Warn("Failed to close local SPDK client")
 		}
 	}()
 
-	engine, err := c.EngineGet(req.EngineName)
+	engine, err := localClient.EngineGet(req.EngineName)
 	if err != nil {
 		return nil, grpcstatus.Errorf(grpccodes.Internal, "failed to get engine %v: %v", req.EngineName, err)
 	}
@@ -104,15 +109,49 @@ func (ops V2DataEngineProxyOps) VolumeGet(ctx context.Context, req *rpc.ProxyEng
 	lastExpansionError := engine.LastExpansionError
 	lastExpansionFailedAt := engine.LastExpansionFailedAt
 	if req.EngineFrontendName != "" {
-		engineFrontend, err := c.EngineFrontendGet(req.EngineFrontendName)
-		if err == nil && engineFrontend != nil {
-			size = int64(engineFrontend.SpecSize)
-			endpoint = engineFrontend.Endpoint
-			frontend = engineFrontend.Frontend
-			isExpanding = engine.IsExpanding || engineFrontend.IsExpanding
-			if engineFrontend.LastExpansionError != "" {
-				lastExpansionError = engineFrontend.LastExpansionError
-				lastExpansionFailedAt = engineFrontend.LastExpansionFailedAt
+		// The EngineFrontend may be on a remote IM. Use req.Address
+		// (which points to the EF IM's SPDK service) to reach it.
+		efClient, err := getSPDKClientFromAddress(req.Address)
+		if err != nil {
+			logrus.WithFields(logrus.Fields{
+				"serviceURL":         req.Address,
+				"engineFrontendName": req.EngineFrontendName,
+			}).WithError(err).Warn("Failed to get SPDK client for engine frontend, returning engine-only info")
+		} else {
+			defer func() {
+				if closeErr := efClient.Close(); closeErr != nil {
+					logrus.WithFields(logrus.Fields{
+						"serviceURL":         req.Address,
+						"engineFrontendName": req.EngineFrontendName,
+					}).WithError(closeErr).Warn("Failed to close EF SPDK client")
+				}
+			}()
+			engineFrontend, err := efClient.EngineFrontendGet(req.EngineFrontendName)
+			if err != nil {
+				logrus.WithFields(logrus.Fields{
+					"engineName":         req.EngineName,
+					"volumeName":         req.VolumeName,
+					"dataEngine":         req.DataEngine,
+					"serviceURL":         req.Address,
+					"engineFrontendName": req.EngineFrontendName,
+				}).WithError(err).Warn("Failed to get engine frontend, returning engine-only info")
+			} else if engineFrontend != nil {
+				size = int64(engineFrontend.SpecSize)
+				endpoint = engineFrontend.Endpoint
+				frontend = engineFrontend.Frontend
+				isExpanding = engine.IsExpanding || engineFrontend.IsExpanding
+				if engineFrontend.LastExpansionError != "" {
+					lastExpansionError = engineFrontend.LastExpansionError
+					lastExpansionFailedAt = engineFrontend.LastExpansionFailedAt
+				}
+			} else {
+				logrus.WithFields(logrus.Fields{
+					"engineName":         req.EngineName,
+					"volumeName":         req.VolumeName,
+					"dataEngine":         req.DataEngine,
+					"serviceURL":         req.Address,
+					"engineFrontendName": req.EngineFrontendName,
+				}).Warn("Engine frontend not found, returning engine-only info")
 			}
 		}
 	}