fix: Don't try watching items without resourceVersion

Trying to watch items without resourceVersion will fail.
Instead of failing and retrying every second, wait until
the next resync interval and try again then.

This reduces load and log spam.

Signed-off-by: Daniel Vassdal <daniel@vassdal.org>

Author: ShutterQuick

pkg/cache/cluster.go

@@ -666,6 +666,29 @@ func (c *clusterCache) watchEvents(ctx context.Context, api kube.APIResourceInfo
 			}
 		}
 
+		// If the resourceVersion is still missing, watchutil.NewRetryWatcher will fail.
+		// https://github.com/kubernetes/client-go/blob/78d2af792babf2dd937ba2e2a8d99c753a5eda89/tools/watch/retrywatcher.go#L68-L71
+		// Instead, let's just check if the resourceVersion exists at the next resync ...
+		if resourceVersion == "" {
+			c.log.V(1).Info(fmt.Sprintf("Ignoring watch for %s on %s due to missing resourceVersion", api.GroupKind, c.config.Host))
+
+			var watchResyncTimeoutCh <-chan time.Time
+			if c.watchResyncTimeout > 0 {
+				shouldResync := time.NewTimer(c.watchResyncTimeout)
+				defer shouldResync.Stop()
+				watchResyncTimeoutCh = shouldResync.C
+			}
+
+			for {
+				select {
+				case <-ctx.Done():
+					return nil
+				case <-watchResyncTimeoutCh:
+					return fmt.Errorf("Resyncing %s on %s due to timeout", api.GroupKind, c.config.Host)
+				}
+			}
+		}
+
 		w, err := watchutil.NewRetryWatcher(resourceVersion, &cache.ListWatch{
 			WatchFunc: func(options metav1.ListOptions) (watch.Interface, error) {
 				res, err := resClient.Watch(ctx, options)

pkg/cache/cluster_test.go

@@ -1,9 +1,14 @@
 package cache
 
 import (
+	"bufio"
+	"bytes"
 	"context"
 	"errors"
 	"fmt"
+	"io"
+	"k8s.io/klog/v2/textlogger"
+	"regexp"
 	"sort"
 	"strings"
 	"sync"
@@ -1393,3 +1398,201 @@ func BenchmarkIterateHierarchyV2(b *testing.B) {
 //		})
 //	}
 //}
+func Test_watchEvents_Missing_resourceVersion(t *testing.T) {
+
+	objExample := &unstructured.Unstructured{Object: map[string]any{
+		"apiVersion": "apiservice.example.com/v1",
+		"kind":       "Example",
+		"metadata": map[string]any{
+			"name": "example",
+		},
+	}}
+
+	testCases := []struct {
+		name               string
+		objs               []runtime.Object
+		funAssert          func(t *testing.T, logLines []string)
+		waitForLogLines    []string
+		waitForLogExtra    time.Duration
+		watchResyncTimeout time.Duration
+	}{
+		{
+			name:            "Should_ignore_resource_without_resourceVersion",
+			objs:            []runtime.Object{objExample},
+			waitForLogLines: []string{"Ignoring watch for Example.apiservice.example.com on https://test due to missing resourceVersion"},
+			funAssert: func(t *testing.T, logLines []string) {
+				require.NotContains(t, logLines, fmt.Sprintf("Resyncing Example.apiservice.example.com on https://test due to timeout"))
+			},
+			watchResyncTimeout: defaultWatchResyncTimeout,
+			waitForLogExtra:    0 * time.Millisecond,
+		},
+		{
+			name:            "Should_not_ignore_resource_with_resourceVersion",
+			objs:            []runtime.Object{testDeploy()},
+			waitForLogLines: []string{"Start watch Deployment.apps on https://test"},
+			funAssert: func(t *testing.T, logLines []string) {
+				require.NotContains(t, logLines, fmt.Sprintf("Ignoring watch for Deployment.apps on https://test due to missing resourceVersion"))
+			},
+			watchResyncTimeout: defaultWatchResyncTimeout,
+			waitForLogExtra:    100 * time.Millisecond,
+		},
+		{
+			name:            "Should_retry_ignored_resource_on_next_resync",
+			objs:            []runtime.Object{objExample},
+			waitForLogLines: []string{"Failed to watch Example.apiservice.example.com on https://test: Resyncing Example.apiservice.example.com on https://test due to timeout, retrying in 1s"},
+			funAssert: func(t *testing.T, logLines []string) {
+				require.Contains(t, logLines, fmt.Sprintf("Ignoring watch for Example.apiservice.example.com on https://test due to missing resourceVersion"))
+			},
+			watchResyncTimeout: 10 * time.Millisecond,
+			waitForLogExtra:    100 * time.Millisecond,
+		},
+	}
+
+	readLinesUntil := func(ctx context.Context, buf io.Reader, wantedLines []string, readExtra time.Duration) ([]string, error) {
+		wantedStatuses := map[string]bool{}
+		for _, wantedLine := range wantedLines {
+			wantedStatuses[strings.TrimSuffix(wantedLine, "\r\n")] = false
+		}
+
+		var logLines []string
+		readChan := make(chan interface{})
+		go func() {
+			lineRgx := regexp.MustCompile(`(?ms)^.+?01:00:00\.000000\s+\d+\s+.+?\.go:\d+\]\s+"(?P<msg>.+)"$`)
+
+			for {
+				scanner := bufio.NewScanner(buf)
+				for scanner.Scan() {
+					match := lineRgx.FindStringSubmatch(scanner.Text())
+					readChan <- match[1]
+				}
+
+				if scanner.Err() != nil {
+					readChan <- scanner.Err()
+					return
+				}
+
+				// EOF. Waiting for data.
+				time.Sleep(50 * time.Millisecond)
+			}
+
+			readChan <- nil
+		}()
+
+		var readExtraTimer *time.Timer
+		var readExtraTimeoutChan <-chan time.Time
+
+		for {
+			select {
+			case <-readExtraTimeoutChan:
+				return logLines, ctx.Err()
+			case <-ctx.Done():
+				return logLines, ctx.Err()
+			case read := <-readChan:
+				if err, ok := read.(error); ok {
+					return logLines, err
+				}
+
+				// EOF
+				if read == nil {
+					return logLines, nil
+				}
+
+				logLines = append(logLines, read.(string))
+				if readExtraTimer != nil {
+					continue
+				}
+
+				line := read.(string)
+				if _, ok := wantedStatuses[line]; ok {
+					wantedStatuses[line] = true
+
+					done := true
+					for _, ok := range wantedStatuses {
+						if !ok {
+							done = false
+						}
+					}
+
+					if done {
+						readExtraTimer = time.NewTimer(readExtra)
+						readExtraTimeoutChan = readExtraTimer.C
+					}
+				}
+			}
+		}
+	}
+
+	createCluster := func(opts []UpdateSettingsFunc, objs ...runtime.Object) *clusterCache {
+		client := fake.NewSimpleDynamicClientWithCustomListKinds(scheme.Scheme,
+			map[schema.GroupVersionResource]string{
+				{Group: "apiservice.example.com", Version: "v1", Resource: "examples"}: "ExampleList",
+			},
+			objs...)
+		reactor := client.ReactionChain[0]
+		client.PrependReactor("list", "*", func(action testcore.Action) (handled bool, ret runtime.Object, err error) {
+			handled, ret, err = reactor.React(action)
+			if err != nil || !handled {
+				return
+			}
+
+			// The apiservice.example.com group is for testing missing resourceVersion, so we omit setting it for those responses.
+			retList, ok := ret.(*unstructured.UnstructuredList)
+			if ok && len(retList.Items) > 0 && retList.Items[0].GetObjectKind().GroupVersionKind().Group == "apiservice.example.com" {
+				return
+			}
+
+			// make sure retList response have resource version
+			ret.(metav1.ListInterface).SetResourceVersion("123")
+			return
+		})
+
+		apiResources := []kube.APIResourceInfo{{
+			GroupKind:            schema.GroupKind{Group: "apps", Kind: "Deployment"},
+			GroupVersionResource: schema.GroupVersionResource{Group: "apps", Version: "v1", Resource: "deployments"},
+			Meta:                 metav1.APIResource{Namespaced: true},
+		}, {
+			GroupKind:            schema.GroupKind{Group: "apiservice.example.com", Kind: "Example"},
+			GroupVersionResource: schema.GroupVersionResource{Group: "apiservice.example.com", Version: "v1", Resource: "examples"},
+			Meta:                 metav1.APIResource{Namespaced: false},
+		}}
+
+		opts = append([]UpdateSettingsFunc{
+			SetKubectl(&kubetest.MockKubectlCmd{APIResources: apiResources, DynamicClient: client}),
+		}, opts...)
+
+		cache := NewClusterCache(
+			&rest.Config{Host: "https://test"},
+			opts...,
+		)
+		return cache
+	}
+
+	for _, testCase := range testCases {
+		t.Run(testCase.name, func(t *testing.T) {
+			ctx, _ := context.WithTimeout(context.Background(), 60*time.Second)
+
+			var logBuffer bytes.Buffer
+			logger := textlogger.NewLogger(textlogger.NewConfig(textlogger.Output(&logBuffer), textlogger.Verbosity(1), textlogger.FixedTime(time.Unix(0, 0))))
+
+			cluster := createCluster([]UpdateSettingsFunc{
+				SetLogr(logger),
+				SetWatchResyncTimeout(testCase.watchResyncTimeout),
+			}, testCase.objs...)
+
+			defer func() {
+				cluster.Invalidate()
+			}()
+
+			err := cluster.EnsureSynced()
+			require.NoError(t, err)
+
+			logLines, err := readLinesUntil(ctx, &logBuffer, testCase.waitForLogLines, testCase.waitForLogExtra)
+			require.NoError(t, err)
+			testCase.funAssert(t, logLines)
+			for _, wantedLogLine := range testCase.waitForLogLines {
+				require.Contains(t, logLines, wantedLogLine)
+			}
+		})
+	}
+
+}