Release workload on a non-MNNVL node in a CD

cmd/compute-domain-daemon/computedomain.go

@@ -184,7 +184,10 @@ func (m *ComputeDomainManager) Get(uid string) (*nvapi.ComputeDomain, error) {
 	return cds[0], nil
 }
 
-// onAddOrUpdate handles the addition or update of a ComputeDomain.
+// onAddOrUpdate handles the addition or update of a ComputeDomain. Here, we
+// receive updates not for all CDs in the system, but only for the CD that we
+// are registered for (filtered by CD name). Note that the informer triggers
+// this callback once upon startup for all existing objects.
 func (m *ComputeDomainManager) onAddOrUpdate(ctx context.Context, obj any) error {
 	// Cast the object to a ComputeDomain object
 	o, ok := obj.(*nvapi.ComputeDomain)
@@ -203,13 +206,14 @@ func (m *ComputeDomainManager) onAddOrUpdate(ctx context.Context, obj any) error
 		return nil
 	}
 
+	// Because the informer only filters by name:
 	// Skip ComputeDomains that don't match on UUID
 	if string(cd.UID) != m.config.computeDomainUUID {
-		klog.Errorf("ComputeDomain processed with non-matching UID (%v, %v)", cd.UID, m.config.computeDomainUUID)
+		klog.Warningf("ComputeDomain processed with non-matching UID (%v, %v)", cd.UID, m.config.computeDomainUUID)
 		return nil
 	}
 
-	// Update node info in ComputeDomain
+	// Update node info in ComputeDomain.
 	if err := m.UpdateComputeDomainNodeInfo(ctx, cd); err != nil {
 		return fmt.Errorf("error updating node info in ComputeDomain: %w", err)
 	}
@@ -257,7 +261,10 @@ func (m *ComputeDomainManager) UpdateComputeDomainNodeInfo(ctx context.Context,
 			Name:     m.config.nodeName,
 			CliqueID: m.config.cliqueID,
 			Index:    nextIndex,
+			Status:   nvapi.ComputeDomainStatusNotReady,
 		}
+
+		klog.Infof("CD status does not contain node name '%s' yet, try to insert myself: %v", m.config.nodeName, nodeInfo)
 		newCD.Status.Nodes = append(newCD.Status.Nodes, nodeInfo)
 	}
 
@@ -266,7 +273,7 @@ func (m *ComputeDomainManager) UpdateComputeDomainNodeInfo(ctx context.Context,
 	// across pod restarts.
 	nodeInfo.IPAddress = m.config.podIP
 
-	// Conditionally update its status
+	// Conditionally update global CD status if it's still in its initial status
 	if newCD.Status.Status == "" {
 		newCD.Status.Status = nvapi.ComputeDomainStatusNotReady
 	}
@@ -279,6 +286,7 @@ func (m *ComputeDomainManager) UpdateComputeDomainNodeInfo(ctx context.Context,
 	}
 	m.mutationCache.Mutation(newCD)
 
+	klog.V(2).Infof("Successfully updated CD")
 	return nil
 }
 
@@ -318,6 +326,14 @@ func getNextAvailableIndex(currentCliqueID string, nodes []*nvapi.ComputeDomainN
 		nextIndex++
 	}
 
+	// Skip `maxNodesPerIMEXDomain` check in the special case of no clique ID
+	// being set: this means that this node does not actually run an IMEX daemon
+	// managed by us and the set of nodes in this "noop" mode in this CD is
+	// allowed to grow larger than maxNodesPerIMEXDomain.
+	if currentCliqueID == "" {
+		return nextIndex, nil
+	}
+
 	// Ensure nextIndex is within the range 0..maxNodesPerIMEXDomain
 	if nextIndex < 0 || nextIndex >= maxNodesPerIMEXDomain {
 		return -1, fmt.Errorf("no available indices within maxNodesPerIMEXDomain (%d) for cliqueID %s", maxNodesPerIMEXDomain, currentCliqueID)
@@ -352,7 +368,7 @@ func (m *ComputeDomainManager) MaybePushNodesUpdate(cd *nvapi.ComputeDomain) {
 		m.previousNodes = cd.Status.Nodes
 		m.updatedNodesChan <- cd.Status.Nodes
 	} else {
-		klog.Infof("IP set did not change")
+		klog.V(6).Infof("IP set did not change")
 	}
 }
 

cmd/compute-domain-daemon/main.go

@@ -185,14 +185,6 @@ func newApp() *cli.App {
 
 // Run invokes the IMEX daemon and manages its lifecycle.
 func run(ctx context.Context, cancel context.CancelFunc, flags *Flags) error {
-	// Support heterogeneous compute domain
-	if flags.cliqueID == "" {
-		fmt.Println("ClusterUUID and CliqueId are NOT set for GPUs on this node.")
-		fmt.Println("The IMEX daemon will not be started.")
-		fmt.Println("Sleeping forever...")
-		<-ctx.Done()
-		return nil
-	}
 
 	config := &ControllerConfig{
 		cliqueID:               flags.cliqueID,
@@ -207,7 +199,17 @@ func run(ctx context.Context, cancel context.CancelFunc, flags *Flags) error {
 	}
 	klog.Infof("config: %v", config)
 
-	// Write the IMEX config with the current pod IP before starting the daemon
+	// Support heterogeneous ComputeDomains. That means that a CD may contain
+	// nodes that do not take part in Multi-Node NVLink communication. On such
+	// nodes, this program is started with an empty NVLink clique ID
+	// configuration parameter. In this mode, do not start the IMEX daemon but
+	// otherwise keep business logic intact. In particular, continuously update
+	// this node's state in the CD object.
+	if flags.cliqueID == "" {
+		klog.Infof("no cliqueID: register with ComputeDomain, but do not run IMEX daemon")
+	}
+
+	// Render and write the IMEX daemon config with the current pod IP
 	if err := writeIMEXConfig(flags.podIP); err != nil {
 		return fmt.Errorf("writeIMEXConfig failed: %w", err)
 	}
@@ -302,6 +304,11 @@ func IMEXDaemonUpdateLoopWithIPs(ctx context.Context, controller *Controller, cl
 				return fmt.Errorf("writeNodesConfig failed: %w", err)
 			}
 
+			if cliqueID == "" {
+				klog.V(1).Infof("empty cliqueID: do not start IMEX daemon")
+				break
+			}
+
 			klog.Infof("Got update, (re)start IMEX daemon")
 			if err := pm.Restart(); err != nil {
 				// This might be a permanent problem, and retrying upon next update
@@ -331,6 +338,11 @@ func IMEXDaemonUpdateLoopWithDNSNames(ctx context.Context, controller *Controlle
 				return fmt.Errorf("failed to update DNS name => IP mappings: %w", err)
 			}
 
+			if dnsNameManager.cliqueID == "" {
+				klog.V(1).Infof("empty cliqueID: do not start IMEX daemon")
+				break
+			}
+
 			fresh, err := processManager.EnsureStarted()
 			if err != nil {
 				return fmt.Errorf("failed to ensure IMEX daemon is started: %w", err)
@@ -344,7 +356,7 @@ func IMEXDaemonUpdateLoopWithDNSNames(ctx context.Context, controller *Controlle
 			// addresses compared to the old set (then we don't need to force
 			// the daemon to re-resolve & re-connect).
 			if !updated || fresh {
-				continue
+				break
 			}
 
 			// Actively ask the IMEX daemon to re-read its config and to
@@ -365,7 +377,7 @@ func IMEXDaemonUpdateLoopWithDNSNames(ctx context.Context, controller *Controlle
 // It returns an error if any step fails.
 func check(ctx context.Context, cancel context.CancelFunc, flags *Flags) error {
 	if flags.cliqueID == "" {
-		fmt.Println("ClusterUUID and CliqueId are NOT set for GPUs on this node.")
+		fmt.Println("check succeeded (noop, clique ID is empty)")
 		return nil
 	}
 
@@ -405,6 +417,12 @@ func writeIMEXConfig(podIP string) error {
 		return fmt.Errorf("error executing template: %w", err)
 	}
 
+	// Ensure the directory exists
+	dir := filepath.Dir(imexConfigPath)
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return fmt.Errorf("failed to create directory %s: %w", dir, err)
+	}
+
 	if err := os.WriteFile(imexConfigPath, configFile.Bytes(), 0644); err != nil {
 		return fmt.Errorf("error writing config file %v: %w", imexConfigPath, err)
 	}

cmd/compute-domain-daemon/podmanager.go

@@ -161,7 +161,7 @@ func (pm *PodManager) updateNodeStatus(ctx context.Context, status string) error
 		return fmt.Errorf("failed to get ComputeDomain: %w", err)
 	}
 	if cd == nil {
-		return fmt.Errorf("ComputeDomain not found")
+		return fmt.Errorf("ComputeDomain '%s/%s' not found", pm.config.computeDomainName, pm.config.computeDomainUUID)
 	}
 
 	// Create a deep copy to avoid modifying the original

cmd/compute-domain-daemon/process.go

@@ -201,8 +201,7 @@ func (m *ProcessManager) Watchdog(ctx context.Context) error {
 	}
 }
 
-// Detect if process terminated unexpectedly. Caller must ignore bool if err
-// isn't nil.
+// Detect if process terminated unexpectedly.
 func (m *ProcessManager) lost() bool {
 	if !m.TryLock() {
 		// Start or stop is in progress; do not inspect state.

cmd/compute-domain-kubelet-plugin/computedomain.go

@@ -60,7 +60,7 @@ type ComputeDomainManager struct {
 
 type ComputeDomainDaemonSettings struct {
 	manager         *ComputeDomainManager
-	domain          string
+	domainID        string
 	rootDir         string
 	configTmplPath  string
 	nodesConfigPath string
@@ -128,13 +128,13 @@ func (m *ComputeDomainManager) Stop() error {
 	return nil
 }
 
-func (m *ComputeDomainManager) NewSettings(domain string) *ComputeDomainDaemonSettings {
+func (m *ComputeDomainManager) NewSettings(domainID string) *ComputeDomainDaemonSettings {
 	return &ComputeDomainDaemonSettings{
 		manager:         m,
-		domain:          domain,
-		rootDir:         fmt.Sprintf("%s/%s", m.configFilesRoot, domain),
-		configTmplPath:  fmt.Sprintf("%s/%s/%s", m.configFilesRoot, domain, "config.tmpl.cfg"),
-		nodesConfigPath: fmt.Sprintf("%s/%s/%s", m.configFilesRoot, domain, "nodes_config.cfg"),
+		domainID:        domainID,
+		rootDir:         fmt.Sprintf("%s/%s", m.configFilesRoot, domainID),
+		configTmplPath:  fmt.Sprintf("%s/%s/%s", m.configFilesRoot, domainID, "config.tmpl.cfg"),
+		nodesConfigPath: fmt.Sprintf("%s/%s/%s", m.configFilesRoot, domainID, "nodes_config.cfg"),
 	}
 }
 
@@ -154,17 +154,16 @@ func (m *ComputeDomainManager) GetComputeDomainChannelContainerEdits(devRoot str
 	}
 }
 
-func (s *ComputeDomainDaemonSettings) GetDomain() string {
-	return s.domain
-}
-
-func (s *ComputeDomainDaemonSettings) GetCDIContainerEdits(ctx context.Context, devRoot string, info *nvcapDeviceInfo) (*cdiapi.ContainerEdits, error) {
-	cd, err := s.manager.GetComputeDomain(ctx, s.domain)
+// GetCDIContainerEditsCommon() returns the CDI spec edits always required for
+// launching the CD Daemon (whether or not it tries to launch an IMEX daemon
+// internally).
+func (s *ComputeDomainDaemonSettings) GetCDIContainerEditsCommon(ctx context.Context) (*cdiapi.ContainerEdits, error) {
+	cd, err := s.manager.GetComputeDomain(ctx, s.domainID)
 	if err != nil {
-		return nil, fmt.Errorf("error getting compute domain: %w", err)
+		return nil, fmt.Errorf("error getting compute domain %s: %w", s.domainID, err)
 	}
 	if cd == nil {
-		return nil, fmt.Errorf("compute domain not found: %s", s.domain)
+		return nil, fmt.Errorf("compute domain not found: %s", s.domainID)
 	}
 
 	edits := &cdiapi.ContainerEdits{
@@ -182,6 +181,20 @@ func (s *ComputeDomainDaemonSettings) GetCDIContainerEdits(ctx context.Context,
 					Options:       []string{"rw", "nosuid", "nodev", "bind"},
 				},
 			},
+		},
+	}
+	return edits, nil
+}
+
+func (s *ComputeDomainDaemonSettings) GetDomainID() string {
+	return s.domainID
+}
+
+// GetCDIContainerEditsForImex() returns the CDI spec edits only required for
+// launching the CD daemon when it actually wraps an IMEX daemon.
+func (s *ComputeDomainDaemonSettings) GetCDIContainerEditsForImex(ctx context.Context, devRoot string, info *nvcapDeviceInfo) *cdiapi.ContainerEdits {
+	edits := &cdiapi.ContainerEdits{
+		ContainerEdits: &cdispec.ContainerEdits{
 			DeviceNodes: []*cdispec.DeviceNode{
 				{
 					Path:     info.path,
@@ -193,8 +206,7 @@ func (s *ComputeDomainDaemonSettings) GetCDIContainerEdits(ctx context.Context,
 			},
 		},
 	}
-
-	return edits, nil
+	return edits
 }
 
 func (s *ComputeDomainDaemonSettings) Prepare(ctx context.Context) error {

cmd/compute-domain-kubelet-plugin/device_state.go

@@ -462,7 +462,8 @@ func (s *DeviceState) applyComputeDomainChannelConfig(ctx context.Context, confi
 	}
 
 	for _, info := range s.nvdevlib.nvCapImexChanDevInfos[:chancount] {
-		configState.containerEdits = configState.containerEdits.Append(s.computeDomainManager.GetComputeDomainChannelContainerEdits(s.cdi.devRoot, info))
+		edits := s.computeDomainManager.GetComputeDomainChannelContainerEdits(s.cdi.devRoot, info)
+		configState.containerEdits = configState.containerEdits.Append(edits)
 	}
 
 	return &configState, nil
@@ -491,27 +492,36 @@ func (s *DeviceState) applyComputeDomainDaemonConfig(ctx context.Context, config
 		ComputeDomain: config.DomainID,
 	}
 
-	// Only prepare files to inject to the daemon if IMEX is supported.
-	if s.computeDomainManager.cliqueID != "" {
-		// Parse the device node info for the fabic-imex-mgmt nvcap.
-		nvcapDeviceInfo, err := s.nvdevlib.parseNVCapDeviceInfo(nvidiaCapFabricImexMgmtPath)
-		if err != nil {
-			return nil, fmt.Errorf("error parsing nvcap device info for fabic-imex-mgmt: %w", err)
-		}
+	// Create new ComputeDomain daemon settings from the ComputeDomainManager.
+	computeDomainDaemonSettings := s.computeDomainManager.NewSettings(config.DomainID)
 
-		// Create new ComputeDomain daemon settings from the ComputeDomainManager.
-		computeDomainDaemonSettings := s.computeDomainManager.NewSettings(config.DomainID)
+	// Prepare injecting IMEX daemon config files even if IMEX is not supported.
+	// This for example creates
+	// '/var/lib/kubelet/plugins/compute-domain.nvidia.com/domains/<uid>' on the
+	// host which is used as mount source mapped to /etc/nvidia-imex in the CD
+	// daemon container.
+	if err := computeDomainDaemonSettings.Prepare(ctx); err != nil {
+		return nil, fmt.Errorf("error preparing ComputeDomain daemon settings for requests '%v' in claim '%v': %w", requests, claim.UID, err)
+	}
 
-		// Prepare the new ComputeDomain daemon.
-		if err := computeDomainDaemonSettings.Prepare(ctx); err != nil {
-			return nil, fmt.Errorf("error preparing ComputeDomain daemon settings for requests '%v' in claim '%v': %w", requests, claim.UID, err)
-		}
+	// Always inject CD config details into the CD daemon (regardless of clique
+	// ID being empty or not).
+	edits, err := computeDomainDaemonSettings.GetCDIContainerEditsCommon(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("error getting common container edits for ComputeDomain daemon '%s': %w", config.DomainID, err)
+	}
+	configState.containerEdits = configState.containerEdits.Append(edits)
 
-		// Store information about the ComputeDomain daemon in the configState.
-		edits, err := computeDomainDaemonSettings.GetCDIContainerEdits(ctx, s.cdi.devRoot, nvcapDeviceInfo)
+	// Only inject dev nodes related to
+	// /proc/driver/nvidia/capabilities/fabric-imex-mgmt if IMEX is supported
+	// (if we want to start the IMEX daemon process in the CD daemon pod).
+	if s.computeDomainManager.cliqueID != "" {
+		// Parse the device node info for the fabric-imex-mgmt nvcap.
+		nvcapDeviceInfo, err := s.nvdevlib.parseNVCapDeviceInfo(nvidiaCapFabricImexMgmtPath)
 		if err != nil {
-			return nil, fmt.Errorf("error getting container edits for ComputeDomain daemon for requests '%v' in claim '%v': %w", requests, claim.UID, err)
+			return nil, fmt.Errorf("error parsing nvcap device info for fabric-imex-mgmt: %w", err)
 		}
+		edits := computeDomainDaemonSettings.GetCDIContainerEditsForImex(ctx, s.cdi.devRoot, nvcapDeviceInfo)
 		configState.containerEdits = configState.containerEdits.Append(edits)
 	}