Merge pull request #8850 from killianmuldoon/pr-stop-caching-pods

🐛 ClusterCacheTracker: Stop pod caching when checking workload cluster

Author: k8s-ci-robot

controllers/remote/cluster_cache_tracker.go

@@ -278,13 +278,14 @@ func (t *ClusterCacheTracker) newClusterAccessor(ctx context.Context, cluster cl
 	}
 
 	// Create a client and a cache for the cluster.
-	c, cache, err := t.createClient(ctx, config, cluster, indexes)
+	c, uncachedClient, cache, err := t.createClient(ctx, config, cluster, indexes)
 	if err != nil {
 		return nil, err
 	}
 
 	// Detect if the controller is running on the workload cluster.
-	runningOnCluster, err := t.runningOnWorkloadCluster(ctx, c, cluster)
+	// This function uses an uncached client to ensure pods aren't cached by the long-lived client.
+	runningOnCluster, err := t.runningOnWorkloadCluster(ctx, uncachedClient, cluster)
 	if err != nil {
 		return nil, err
 	}
@@ -303,7 +304,7 @@ func (t *ClusterCacheTracker) newClusterAccessor(ctx context.Context, cluster cl
 		config.Host = inClusterConfig.Host
 
 		// Create a new client and overwrite the previously created client.
-		c, cache, err = t.createClient(ctx, config, cluster, indexes)
+		c, _, cache, err = t.createClient(ctx, config, cluster, indexes)
 		if err != nil {
 			return nil, errors.Wrap(err, "error creating client for self-hosted cluster")
 		}
@@ -355,26 +356,26 @@ func (t *ClusterCacheTracker) runningOnWorkloadCluster(ctx context.Context, c cl
 	return t.controllerPodMetadata.UID == pod.UID, nil
 }
 
-// createClient creates a client and a mapper based on a rest.Config.
-func (t *ClusterCacheTracker) createClient(ctx context.Context, config *rest.Config, cluster client.ObjectKey, indexes []Index) (client.Client, *stoppableCache, error) {
+// createClient creates a cached client, and uncached client and a mapper based on a rest.Config.
+func (t *ClusterCacheTracker) createClient(ctx context.Context, config *rest.Config, cluster client.ObjectKey, indexes []Index) (client.Client, client.Client, *stoppableCache, error) {
 	// Create a http client for the cluster.
 	httpClient, err := rest.HTTPClientFor(config)
 	if err != nil {
-		return nil, nil, errors.Wrapf(err, "error creating client for remote cluster %q: error creating http client", cluster.String())
+		return nil, nil, nil, errors.Wrapf(err, "error creating client for remote cluster %q: error creating http client", cluster.String())
 	}
 
 	// Create a mapper for it
 	mapper, err := apiutil.NewDynamicRESTMapper(config, httpClient)
 	if err != nil {
-		return nil, nil, errors.Wrapf(err, "error creating client for remote cluster %q: error creating dynamic rest mapper", cluster.String())
+		return nil, nil, nil, errors.Wrapf(err, "error creating client for remote cluster %q: error creating dynamic rest mapper", cluster.String())
 	}
 
 	// Verify if we can get a rest mapping from the workload cluster apiserver.
 	// Note: This also checks if the apiserver is up in general. We do this already here
 	// to avoid further effort creating a cache and a client and to produce a clearer error message.
 	_, err = mapper.RESTMapping(corev1.SchemeGroupVersion.WithKind("Node").GroupKind(), corev1.SchemeGroupVersion.Version)
 	if err != nil {
-		return nil, nil, errors.Wrapf(err, "error creating client for remote cluster %q: error getting rest mapping", cluster.String())
+		return nil, nil, nil, errors.Wrapf(err, "error creating client for remote cluster %q: error getting rest mapping", cluster.String())
 	}
 
 	// Create the cache for the remote cluster
@@ -385,7 +386,7 @@ func (t *ClusterCacheTracker) createClient(ctx context.Context, config *rest.Con
 	}
 	remoteCache, err := cache.New(config, cacheOptions)
 	if err != nil {
-		return nil, nil, errors.Wrapf(err, "error creating client for remote cluster %q: error creating cache", cluster.String())
+		return nil, nil, nil, errors.Wrapf(err, "error creating client for remote cluster %q: error creating cache", cluster.String())
 	}
 
 	cacheCtx, cacheCtxCancel := context.WithCancel(ctx)
@@ -398,12 +399,12 @@ func (t *ClusterCacheTracker) createClient(ctx context.Context, config *rest.Con
 
 	for _, index := range indexes {
 		if err := cache.IndexField(ctx, index.Object, index.Field, index.ExtractValue); err != nil {
-			return nil, nil, errors.Wrapf(err, "error adding index for field %q to cache for remote cluster %q", index.Field, cluster.String())
+			return nil, nil, nil, errors.Wrapf(err, "error adding index for field %q to cache for remote cluster %q", index.Field, cluster.String())
 		}
 	}
 
 	// Create the client for the remote cluster
-	c, err := client.New(config, client.Options{
+	cachedClient, err := client.New(config, client.Options{
 		Scheme:     t.scheme,
 		Mapper:     mapper,
 		HTTPClient: httpClient,
@@ -414,9 +415,19 @@ func (t *ClusterCacheTracker) createClient(ctx context.Context, config *rest.Con
 		},
 	})
 	if err != nil {
-		return nil, nil, errors.Wrapf(err, "error creating client for remote cluster %q", cluster.String())
+		return nil, nil, nil, errors.Wrapf(err, "error creating client for remote cluster %q", cluster.String())
 	}
 
+	// Create an uncached client. This is used in `runningOnWorkloadCluster` to ensure we don't continuously cache
+	// pods in the client.
+	uncachedClient, err := client.New(config, client.Options{
+		Scheme:     t.scheme,
+		Mapper:     mapper,
+		HTTPClient: httpClient,
+	})
+	if err != nil {
+		return nil, nil, nil, errors.Wrapf(err, "error creating uncached client for remote cluster %q", cluster.String())
+	}
 	// Start the cache!!!
 	go cache.Start(cacheCtx) //nolint:errcheck
 
@@ -425,7 +436,7 @@ func (t *ClusterCacheTracker) createClient(ctx context.Context, config *rest.Con
 	defer cacheSyncCtxCancel()
 	if !cache.WaitForCacheSync(cacheSyncCtx) {
 		cache.Stop()
-		return nil, nil, fmt.Errorf("failed waiting for cache for remote cluster %v to sync: %w", cluster, cacheCtx.Err())
+		return nil, nil, nil, fmt.Errorf("failed waiting for cache for remote cluster %v to sync: %w", cluster, cacheCtx.Err())
 	}
 
 	// Start cluster healthcheck!!!
@@ -435,7 +446,7 @@ func (t *ClusterCacheTracker) createClient(ctx context.Context, config *rest.Con
 		httpClient: httpClient,
 	})
 
-	return c, cache, nil
+	return cachedClient, uncachedClient, cache, nil
 }
 
 // deleteAccessor stops a clusterAccessor's cache and removes the clusterAccessor from the tracker.