fix(distributed): pass ExternalURI through NATS backend install (#9446)

When installing a backend with a custom OCI URI in distributed mode,
the URI was captured in ManagementOp.ExternalURI by the HTTP handler
but never forwarded to workers. BackendInstallRequest had no URI field,
so workers fell through to the gallery lookup and failed with
"no backend found with name <custom-name>".

Add URI/Name/Alias fields to BackendInstallRequest and thread them from
ManagementOp through DistributedBackendManager.InstallBackend() and the
RemoteUnloaderAdapter. On the worker side, route to InstallExternalBackend
when URI is set instead of InstallBackendFromGallery. Update all
remaining InstallBackend call sites (UpgradeBackend, reconciler
pending-op drain, router auto-install) to pass empty strings for the
new params.

Assisted-by: Claude Code:claude-sonnet-4-6

Signed-off-by: Russell Sim <rsl@simopolis.xyz>

core/cli/worker.go

@@ -21,6 +21,7 @@ import (
 	"github.com/mudler/LocalAI/core/cli/workerregistry"
 	"github.com/mudler/LocalAI/core/config"
 	"github.com/mudler/LocalAI/core/gallery"
+	"github.com/mudler/LocalAI/core/services/galleryop"
 	"github.com/mudler/LocalAI/core/services/messaging"
 	"github.com/mudler/LocalAI/core/services/nodes"
 	"github.com/mudler/LocalAI/core/services/storage"
@@ -597,12 +598,20 @@ func (s *backendSupervisor) installBackend(req messaging.BackendInstallRequest)
 	// Try to find the backend binary
 	backendPath := s.findBackend(req.Backend)
 	if backendPath == "" {
-		// Backend not found locally — try auto-installing from gallery
-		xlog.Info("Backend not found locally, attempting gallery install", "backend", req.Backend)
-		if err := gallery.InstallBackendFromGallery(
-			context.Background(), galleries, s.systemState, s.ml, req.Backend, nil, false,
-		); err != nil {
-			return "", fmt.Errorf("installing backend from gallery: %w", err)
+		if req.URI != "" {
+			xlog.Info("Backend not found locally, attempting external install", "backend", req.Backend, "uri", req.URI)
+			if err := galleryop.InstallExternalBackend(
+				context.Background(), galleries, s.systemState, s.ml, nil, req.URI, req.Name, req.Alias,
+			); err != nil {
+				return "", fmt.Errorf("installing backend from gallery: %w", err)
+			}
+		} else {
+			xlog.Info("Backend not found locally, attempting gallery install", "backend", req.Backend)
+			if err := gallery.InstallBackendFromGallery(
+				context.Background(), galleries, s.systemState, s.ml, req.Backend, nil, false,
+			); err != nil {
+				return "", fmt.Errorf("installing backend from gallery: %w", err)
+			}
 		}
 		// Re-register after install and retry
 		gallery.RegisterBackends(s.systemState, s.ml)

core/http/endpoints/localai/nodes.go

@@ -376,7 +376,7 @@ func InstallBackendOnNodeEndpoint(unloader nodes.NodeCommandSender) echo.Handler
 		if err := c.Bind(&req); err != nil || req.Backend == "" {
 			return c.JSON(http.StatusBadRequest, nodeError(http.StatusBadRequest, "backend name required"))
 		}
-		reply, err := unloader.InstallBackend(nodeID, req.Backend, "", req.BackendGalleries)
+		reply, err := unloader.InstallBackend(nodeID, req.Backend, "", req.BackendGalleries, "", "", "")
 		if err != nil {
 			xlog.Error("Failed to install backend on node", "node", nodeID, "backend", req.Backend, "error", err)
 			return c.JSON(http.StatusInternalServerError, nodeError(http.StatusInternalServerError, "failed to install backend on node"))

core/services/messaging/subjects.go

@@ -124,8 +124,13 @@ func SubjectNodeBackendInstall(nodeID string) string {
 // BackendInstallRequest is the payload for a backend.install NATS request.
 type BackendInstallRequest struct {
 	Backend          string `json:"backend"`
-	ModelID          string `json:"model_id,omitempty"` // unique model identifier — each model gets its own gRPC process
+	ModelID          string `json:"model_id,omitempty"`
 	BackendGalleries string `json:"backend_galleries,omitempty"`
+	// URI is set for external installs (OCI image, URL, or path). When non-empty
+	// the worker routes to InstallExternalBackend instead of the gallery lookup.
+	URI   string `json:"uri,omitempty"`
+	Name  string `json:"name,omitempty"`
+	Alias string `json:"alias,omitempty"`
 }
 
 // BackendInstallReply is the response from a backend.install NATS request.

core/services/nodes/managers_distributed.go

@@ -293,7 +293,7 @@ func (d *DistributedBackendManager) InstallBackend(ctx context.Context, op *gall
 	backendName := op.GalleryElementName
 
 	_, err := d.enqueueAndDrainBackendOp(ctx, OpBackendInstall, backendName, galleriesJSON, func(node BackendNode) error {
-		reply, err := d.adapter.InstallBackend(node.ID, backendName, "", string(galleriesJSON))
+		reply, err := d.adapter.InstallBackend(node.ID, backendName, "", string(galleriesJSON), op.ExternalURI, op.ExternalName, op.ExternalAlias)
 		if err != nil {
 			return err
 		}
@@ -311,7 +311,7 @@ func (d *DistributedBackendManager) UpgradeBackend(ctx context.Context, name str
 	galleriesJSON, _ := json.Marshal(d.backendGalleries)
 
 	_, err := d.enqueueAndDrainBackendOp(ctx, OpBackendUpgrade, name, galleriesJSON, func(node BackendNode) error {
-		reply, err := d.adapter.InstallBackend(node.ID, name, "", string(galleriesJSON))
+		reply, err := d.adapter.InstallBackend(node.ID, name, "", string(galleriesJSON), "", "", "")
 		if err != nil {
 			return err
 		}

core/services/nodes/reconciler.go

@@ -188,7 +188,7 @@ func (rc *ReplicaReconciler) drainPendingBackendOps(ctx context.Context) {
 		case OpBackendDelete:
 			_, applyErr = rc.adapter.DeleteBackend(op.NodeID, op.Backend)
 		case OpBackendInstall, OpBackendUpgrade:
-			reply, err := rc.adapter.InstallBackend(op.NodeID, op.Backend, "", string(op.Galleries))
+			reply, err := rc.adapter.InstallBackend(op.NodeID, op.Backend, "", string(op.Galleries), "", "", "")
 			if err != nil {
 				applyErr = err
 			} else if !reply.Success {

core/services/nodes/router.go

@@ -504,7 +504,7 @@ func (r *SmartRouter) installBackendOnNode(ctx context.Context, node *BackendNod
 		return "", fmt.Errorf("no NATS connection for backend installation")
 	}
 
-	reply, err := r.unloader.InstallBackend(node.ID, backendType, modelID, r.galleriesJSON)
+	reply, err := r.unloader.InstallBackend(node.ID, backendType, modelID, r.galleriesJSON, "", "", "")
 	if err != nil {
 		return "", err
 	}

core/services/nodes/router_test.go

@@ -244,7 +244,7 @@ type fakeUnloader struct {
 	unloadErr    error
 }
 
-func (f *fakeUnloader) InstallBackend(_, _, _, _ string) (*messaging.BackendInstallReply, error) {
+func (f *fakeUnloader) InstallBackend(_, _, _, _, _, _, _ string) (*messaging.BackendInstallReply, error) {
 	return f.installReply, f.installErr
 }
 

core/services/nodes/unloader.go

@@ -17,7 +17,7 @@ type backendStopRequest struct {
 // NodeCommandSender abstracts NATS-based commands to worker nodes.
 // Used by HTTP endpoint handlers to avoid coupling to the concrete RemoteUnloaderAdapter.
 type NodeCommandSender interface {
-	InstallBackend(nodeID, backendType, modelID, galleriesJSON string) (*messaging.BackendInstallReply, error)
+	InstallBackend(nodeID, backendType, modelID, galleriesJSON, uri, name, alias string) (*messaging.BackendInstallReply, error)
 	DeleteBackend(nodeID, backendName string) (*messaging.BackendDeleteReply, error)
 	ListBackends(nodeID string) (*messaging.BackendListReply, error)
 	StopBackend(nodeID, backend string) error
@@ -72,7 +72,7 @@ func (a *RemoteUnloaderAdapter) UnloadRemoteModel(modelName string) error {
 // The worker installs the backend from gallery (if not already installed),
 // starts the gRPC process, and replies when ready.
 // Timeout: 5 minutes (gallery install can take a while).
-func (a *RemoteUnloaderAdapter) InstallBackend(nodeID, backendType, modelID, galleriesJSON string) (*messaging.BackendInstallReply, error) {
+func (a *RemoteUnloaderAdapter) InstallBackend(nodeID, backendType, modelID, galleriesJSON, uri, name, alias string) (*messaging.BackendInstallReply, error) {
 	subject := messaging.SubjectNodeBackendInstall(nodeID)
 	xlog.Info("Sending NATS backend.install", "nodeID", nodeID, "backend", backendType, "modelID", modelID)
 
@@ -80,6 +80,9 @@ func (a *RemoteUnloaderAdapter) InstallBackend(nodeID, backendType, modelID, gal
 		Backend:          backendType,
 		ModelID:          modelID,
 		BackendGalleries: galleriesJSON,
+		URI:              uri,
+		Name:             name,
+		Alias:            alias,
 	}, 5*time.Minute)
 }