feat: cache daemon client for each pipeline

server/apis/v1/handler.go

@@ -30,6 +30,7 @@ import (
 	"time"
 
 	"github.com/gin-gonic/gin"
+	lru "github.com/hashicorp/golang-lru"
 	admissionv1 "k8s.io/api/admission/v1"
 	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -57,10 +58,11 @@ const (
 )
 
 type handler struct {
-	kubeClient     kubernetes.Interface
-	metricsClient  *metricsversiond.Clientset
-	numaflowClient dfv1clients.NumaflowV1alpha1Interface
-	dexObj         *DexObject
+	kubeClient         kubernetes.Interface
+	metricsClient      *metricsversiond.Clientset
+	numaflowClient     dfv1clients.NumaflowV1alpha1Interface
+	daemonClientsCache *lru.Cache
+	dexObj             *DexObject
 }
 
 // NewHandler is used to provide a new instance of the handler type
@@ -79,11 +81,15 @@ func NewHandler(dexObj *DexObject) (*handler, error) {
 	}
 	metricsClient := metricsversiond.NewForConfigOrDie(k8sRestConfig)
 	numaflowClient := dfv1versiond.NewForConfigOrDie(k8sRestConfig).NumaflowV1alpha1()
+	daemonClientsCache, _ := lru.NewWithEvict(100, func(key, value interface{}) {
+		_ = value.(*daemonclient.DaemonClient).Close()
+	})
 	return &handler{
-		kubeClient:     kubeClient,
-		metricsClient:  metricsClient,
-		numaflowClient: numaflowClient,
-		dexObj:         dexObj,
+		kubeClient:         kubeClient,
+		metricsClient:      metricsClient,
+		numaflowClient:     numaflowClient,
+		daemonClientsCache: daemonClientsCache,
+		dexObj:             dexObj,
 	}, nil
 }
 
@@ -313,13 +319,11 @@ func (h *handler) GetPipeline(c *gin.Context) {
 	}
 
 	// get pipeline lag
-	// TODO: the client should be cached.
-	client, err := daemonclient.NewDaemonServiceClient(daemonSvcAddress(ns, pipeline))
-	if err != nil {
-		h.respondWithError(c, fmt.Sprintf("Failed to fetch pipeline: failed to calculate lag for pipeline %q: %s", pipeline, err.Error()))
+	client, err := h.getDaemonClient(ns, pipeline)
+	if err != nil || client == nil {
+		h.respondWithError(c, fmt.Sprintf("failed to get daemon service client for pipeline %q, %s", pipeline, err.Error()))
 		return
 	}
-	defer client.Close()
 
 	var (
 		minWM int64 = math.MaxInt64
@@ -421,6 +425,9 @@ func (h *handler) DeletePipeline(c *gin.Context) {
 		return
 	}
 
+	// cleanup client after successfully deleting pipeline
+	h.daemonClientsCache.Remove(daemonSvcAddress(ns, pipeline))
+
 	c.JSON(http.StatusOK, NewNumaflowAPIResponse(nil, nil))
 }
 
@@ -580,13 +587,11 @@ func (h *handler) DeleteInterStepBufferService(c *gin.Context) {
 func (h *handler) ListPipelineBuffers(c *gin.Context) {
 	ns, pipeline := c.Param("namespace"), c.Param("pipeline")
 
-	// TODO: the client should be cached.
-	client, err := daemonclient.NewDaemonServiceClient(daemonSvcAddress(ns, pipeline))
-	if err != nil {
-		h.respondWithError(c, fmt.Sprintf("Failed to get the Inter-Step buffers for pipeline %q: %s", pipeline, err.Error()))
+	client, err := h.getDaemonClient(ns, pipeline)
+	if err != nil || client == nil {
+		h.respondWithError(c, fmt.Sprintf("failed to get daemon service client for pipeline %q, %s", pipeline, err.Error()))
 		return
 	}
-	defer client.Close()
 
 	buffers, err := client.ListPipelineBuffers(context.Background(), pipeline)
 	if err != nil {
@@ -601,13 +606,11 @@ func (h *handler) ListPipelineBuffers(c *gin.Context) {
 func (h *handler) GetPipelineWatermarks(c *gin.Context) {
 	ns, pipeline := c.Param("namespace"), c.Param("pipeline")
 
-	// TODO: the client should be cached.
-	client, err := daemonclient.NewDaemonServiceClient(daemonSvcAddress(ns, pipeline))
-	if err != nil {
-		h.respondWithError(c, fmt.Sprintf("Failed to get the watermarks for pipeline %q: %s", pipeline, err.Error()))
+	client, err := h.getDaemonClient(ns, pipeline)
+	if err != nil || client == nil {
+		h.respondWithError(c, fmt.Sprintf("failed to get daemon service client for pipeline %q, %s", pipeline, err.Error()))
 		return
 	}
-	defer client.Close()
 
 	watermarks, err := client.GetPipelineWatermarks(context.Background(), pipeline)
 	if err != nil {
@@ -681,13 +684,11 @@ func (h *handler) GetVerticesMetrics(c *gin.Context) {
 		return
 	}
 
-	// TODO: the client should be cached.
-	client, err := daemonclient.NewDaemonServiceClient(daemonSvcAddress(ns, pipeline))
-	if err != nil {
-		h.respondWithError(c, fmt.Sprintf("Failed to get the vertices metrics: failed to get demon service client for namespace %q pipeline %q: %s", ns, pipeline, err.Error()))
+	client, err := h.getDaemonClient(ns, pipeline)
+	if err != nil || client == nil {
+		h.respondWithError(c, fmt.Sprintf("failed to get daemon service client for pipeline %q, %s", pipeline, err.Error()))
 		return
 	}
-	defer client.Close()
 
 	var results = make(map[string][]*daemon.VertexMetrics)
 	for _, vertex := range pl.Spec.Vertices {
@@ -975,3 +976,24 @@ func validateNamespace(h *handler, pipeline *dfv1.Pipeline, ns string) error {
 func daemonSvcAddress(ns, pipeline string) string {
 	return fmt.Sprintf("%s.%s.svc:%d", fmt.Sprintf("%s-daemon-svc", pipeline), ns, dfv1.DaemonServicePort)
 }
+
+func (h *handler) getDaemonClient(ns, pipeline string) (*daemonclient.DaemonClient, error) {
+	dClient, ok := h.daemonClientsCache.Get(daemonSvcAddress(ns, pipeline))
+	if !ok {
+		dClient, err := daemonclient.NewDaemonServiceClient(daemonSvcAddress(ns, pipeline))
+		if err != nil {
+			return nil, err
+		}
+		if dClient == nil {
+			return nil, fmt.Errorf("nil client")
+		}
+		h.daemonClientsCache.Add(daemonSvcAddress(ns, pipeline), dClient)
+	}
+
+	client, ok := dClient.(*daemonclient.DaemonClient)
+	if !ok {
+		return nil, fmt.Errorf("failed to get client")
+	}
+
+	return client, nil
+}