apiserver: start only one compactor per unique storage transport config

staging/src/k8s.io/apiserver/pkg/storage/storagebackend/factory/etcd3.go

@@ -19,6 +19,7 @@ package factory
 import (
 	"context"
 	"fmt"
+	"sync"
 	"sync/atomic"
 	"time"
 
@@ -108,16 +109,88 @@ func newETCD3Client(c storagebackend.TransportConfig) (*clientv3.Client, error)
 	return clientv3.New(cfg)
 }
 
+type runningCompactor struct {
+	interval time.Duration
+	cancel   context.CancelFunc
+	client   *clientv3.Client
+	refs     int
+}
+
+var (
+	lock       sync.Mutex
+	compactors = map[string]*runningCompactor{}
+)
+
+// startCompactorOnce start one compactor per transport. If the interval get smaller on repeated calls, the
+// compactor is replaced. A destroy func is returned. If all destroy funcs with the same transport are called,
+// the compactor is stopped.
+func startCompactorOnce(c storagebackend.TransportConfig, interval time.Duration) (func(), error) {
+	lock.Lock()
+	defer lock.Unlock()
+
+	key := fmt.Sprintf("%v", c) // gives: {[server1 server2] keyFile certFile caFile}
+	if compactor, foundBefore := compactors[key]; !foundBefore || compactor.interval > interval {
+		compactorClient, err := newETCD3Client(c)
+		if err != nil {
+			return nil, err
+		}
+
+		if foundBefore {
+			// replace compactor
+			compactor.cancel()
+			compactor.client.Close()
+		} else {
+			// start new compactor
+			compactor = &runningCompactor{}
+			compactors[key] = compactor
+		}
+
+		ctx, cancel := context.WithCancel(context.Background())
+
+		compactor.interval = interval
+		compactor.cancel = cancel
+		compactor.client = compactorClient
+
+		etcd3.StartCompactor(ctx, compactorClient, interval)
+	}
+
+	compactors[key].refs++
+
+	return func() {
+		lock.Lock()
+		defer lock.Unlock()
+
+		compactor := compactors[key]
+		compactor.refs--
+		if compactor.refs == 0 {
+			compactor.cancel()
+			compactor.client.Close()
+			delete(compactors, key)
+		}
+	}, nil
+}
+
 func newETCD3Storage(c storagebackend.Config) (storage.Interface, DestroyFunc, error) {
-	client, err := newETCD3Client(c.Transport)
+	stopCompactor, err := startCompactorOnce(c.Transport, c.CompactionInterval)
 	if err != nil {
 		return nil, nil, err
 	}
-	ctx, cancel := context.WithCancel(context.Background())
-	etcd3.StartCompactor(ctx, client, c.CompactionInterval)
+
+	client, err := newETCD3Client(c.Transport)
+	if err != nil {
+		stopCompactor()
+		return nil, nil, err
+	}
+
+	var once sync.Once
 	destroyFunc := func() {
-		cancel()
-		client.Close()
+		// we know that storage destroy funcs are called multiple times (due to reuse in subresources).
+		// Hence, we only destroy once.
+		// TODO: fix duplicated storage destroy calls higher level
+		once.Do(func() {
+			stopCompactor()
+			client.Close()
+		})
 	}
 	transformer := c.Transformer
 	if transformer == nil {

test/integration/etcd/server.go

@@ -74,7 +74,7 @@ func StartRealMasterOrDie(t *testing.T) *Master {
 	kubeAPIServerOptions.InsecureServing.BindPort = 0
 	kubeAPIServerOptions.SecureServing.Listener = listener
 	kubeAPIServerOptions.SecureServing.ServerCert.CertDirectory = certDir
-	kubeAPIServerOptions.Etcd.StorageConfig.ServerList = []string{framework.GetEtcdURL()}
+	kubeAPIServerOptions.Etcd.StorageConfig.Transport.ServerList = []string{framework.GetEtcdURL()}
 	kubeAPIServerOptions.Etcd.DefaultStorageMediaType = runtime.ContentTypeJSON // force json we can easily interpret the result in etcd
 	kubeAPIServerOptions.ServiceClusterIPRange = *defaultServiceClusterIPRange
 	kubeAPIServerOptions.Authorization.Modes = []string{"RBAC"}
@@ -88,7 +88,7 @@ func StartRealMasterOrDie(t *testing.T) *Master {
 	}
 
 	// get etcd client before starting API server
-	rawClient, kvClient, err := integration.GetEtcdClients(completedOptions.Etcd.StorageConfig)
+	rawClient, kvClient, err := integration.GetEtcdClients(completedOptions.Etcd.StorageConfig.Transport)
 	if err != nil {
 		t.Fatal(err)
 	}