ClusterCacheTracker: improve error when workload cluster is not

reachable

Signed-off-by: Stefan Büringer [email protected]

controllers/remote/cluster_cache_tracker.go

@@ -345,13 +345,21 @@ func (t *ClusterCacheTracker) createClient(ctx context.Context, config *rest.Con
 	// Create a http client for the cluster.
 	httpClient, err := rest.HTTPClientFor(config)
 	if err != nil {
-		return nil, nil, errors.Wrapf(err, "error creating http client for remote cluster %q", cluster.String())
+		return 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 dynamic rest mapper for remote cluster %q", cluster.String())
+		return 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(clusterv1.GroupVersion.WithKind("Cluster").GroupKind(), clusterv1.GroupVersion.Version)
+	if err != nil {
+		return 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
@@ -362,7 +370,7 @@ 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 cache for remote cluster %q", cluster.String())
+		return nil, nil, errors.Wrapf(err, "error creating client for remote cluster %q: error creating cache", cluster.String())
 	}
 
 	cacheCtx, cacheCtxCancel := context.WithCancel(ctx)
@@ -373,12 +381,6 @@ func (t *ClusterCacheTracker) createClient(ctx context.Context, config *rest.Con
 		cancelFunc: cacheCtxCancel,
 	}
 
-	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())
-		}
-	}
-
 	// Create the client for the remote cluster
 	c, err := client.New(config, client.Options{
 		Scheme:     t.scheme,
@@ -394,6 +396,12 @@ func (t *ClusterCacheTracker) createClient(ctx context.Context, config *rest.Con
 		return nil, nil, errors.Wrapf(err, "error creating client for remote cluster %q", cluster.String())
 	}
 
+	for _, index := range indexes {
+		if err := cache.IndexField(ctx, index.Object, index.Field, index.ExtractValue); err != nil {
+			return nil, nil, errors.Wrapf(err, "error creating client for remote cluster %q: error adding index for field %q to cache", cluster.String(), index.Field)
+		}
+	}
+
 	// Start the cache!!!
 	go cache.Start(cacheCtx) //nolint:errcheck