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Add HTTP 410 (Gone) status code checks to reflector and relist with RV=''

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Kubernetes-commit: e2fe126d485af243d45f06bafd2ca83931881429
This commit is contained in:
Joe Betz 2019-10-09 16:45:32 -07:00 committed by Kubernetes Publisher
parent 54033229aa
commit a3f022a93c
1 changed files with 55 additions and 25 deletions
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80
tools/cache/reflector.go vendored
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@ -74,6 +74,9 @@ type Reflector struct {
// observed when doing a sync with the underlying store
// it is thread safe, but not synchronized with the underlying store
lastSyncResourceVersion string
// isLastSyncResourceVersionGone is true if the previous list or watch request with lastSyncResourceVersion
// failed with an HTTP 410 (Gone) status code.
isLastSyncResourceVersionGone bool
// lastSyncResourceVersionMutex guards read/write access to lastSyncResourceVersion
lastSyncResourceVersionMutex sync.RWMutex
// WatchListPageSize is the requested chunk size of initial and resync watch lists.
@ -208,19 +211,16 @@ func (r *Reflector) ListAndWatch(stopCh <-chan struct{}) error {
if r.WatchListPageSize != 0 {
pager.PageSize = r.WatchListPageSize
}
// Pager falls back to full list if paginated list calls fail due to an "Expired" error on the 2nd page or later,
// but still my return an "Expired" error if the 1st page fails with "Expired" or the full list fails with "Expired".
list, err = pager.List(context.Background(), options)
if apierrs.IsResourceExpired(err) {
// For Kubernetes 1.16 and earlier, if the watch cache is disabled for a resource, list requests
// with LastSyncResourceVersion set to a non-zero ResourceVersion will fail if the exact ResourceVersion
// requested is expired (e.g. an etcd compaction has remove it).
// To prevent the reflector from getting stuck retrying a list for an expired resource version in this
// case, we set ResourceVersion="" and list again to re-establish reflector to the latest available
// ResourceVersion, using a consistent read from etcd. This is also safe to do if watch cache is enabled
// and the list request returned a "Expired" error.
options = metav1.ListOptions{ResourceVersion: ""}
list, err = pager.List(context.Background(), options)
if isExpiredError(err) {
r.setIsLastSyncResourceVersionExpired(true)
// Retry immediately if the resource version used to list is expired.
// The pager already falls back to full list if paginated list calls fail due to an "Expired" error on
// continuation pages, but the pager might not be enabled, or the full list might fail because the
// resource version it is listing at is expired, so we need to fallback to resourceVersion="" in all
// to recover and ensure the reflector makes forward progress.
list, err = pager.List(context.Background(), metav1.ListOptions{ResourceVersion: r.relistResourceVersion()})
}
close(listCh)
}()
@ -234,6 +234,7 @@ func (r *Reflector) ListAndWatch(stopCh <-chan struct{}) error {
if err != nil {
return fmt.Errorf("%s: Failed to list %v: %v", r.name, r.expectedTypeName, err)
}
r.setIsLastSyncResourceVersionExpired(false) // list was successful
initTrace.Step("Objects listed")
listMetaInterface, err := meta.ListAccessor(list)
if err != nil {
@ -307,10 +308,13 @@ func (r *Reflector) ListAndWatch(stopCh <-chan struct{}) error {
w, err := r.listerWatcher.Watch(options)
if err != nil {
switch err {
case io.EOF:
switch {
case isExpiredError(err):
r.setIsLastSyncResourceVersionExpired(true)
klog.V(4).Infof("%s: watch of %v closed with: %v", r.name, r.expectedTypeName, err)
case err == io.EOF:
// watch closed normally
case io.ErrUnexpectedEOF:
case err == io.ErrUnexpectedEOF:
klog.V(1).Infof("%s: Watch for %v closed with unexpected EOF: %v", r.name, r.expectedTypeName, err)
default:
utilruntime.HandleError(fmt.Errorf("%s: Failed to watch %v: %v", r.name, r.expectedTypeName, err))
@ -329,7 +333,8 @@ func (r *Reflector) ListAndWatch(stopCh <-chan struct{}) error {
if err := r.watchHandler(w, &resourceVersion, resyncerrc, stopCh); err != nil {
if err != errorStopRequested {
switch {
case apierrs.IsResourceExpired(err):
case isExpiredError(err):
r.setIsLastSyncResourceVersionExpired(true)
klog.V(4).Infof("%s: watch of %v ended with: %v", r.name, r.expectedTypeName, err)
default:
klog.Warningf("%s: watch of %v ended with: %v", r.name, r.expectedTypeName, err)
@ -442,16 +447,41 @@ func (r *Reflector) setLastSyncResourceVersion(v string) {
r.lastSyncResourceVersion = v
}
// relistResourceVersion is the resource version the reflector should list or relist from.
// relistResourceVersion determines the resource version the reflector should list or relist from.
// Returns either the lastSyncResourceVersion so that this reflector will relist with a resource
// versions no older than has already been observed in relist results or watch events, or, if the last relist resulted
// in an HTTP 410 (Gone) status code, returns "" so that the relist will use the latest resource version available in
// etcd via a quorum read.
func (r *Reflector) relistResourceVersion() string {
lastSyncRV := r.LastSyncResourceVersion()
if lastSyncRV == "" {
// Explicitly set resource version to have it list from cache for
// performance reasons.
// It's fine for the returned state to be stale (we will catch up via Watch()
// eventually), but we need to be at least as new as the last resource version we
// synced to avoid going back in time.
r.lastSyncResourceVersionMutex.RLock()
defer r.lastSyncResourceVersionMutex.RUnlock()
if r.isLastSyncResourceVersionGone {
// Since this reflector makes paginated list requests, and all paginated list requests skip the watch cache
// if the lastSyncResourceVersion is expired, we set ResourceVersion="" and list again to re-establish reflector
// to the latest available ResourceVersion, using a consistent read from etcd.
return ""
}
if r.lastSyncResourceVersion == "" {
// For performance reasons, initial list performed by reflector uses "0" as resource version to allow it to
// be served from the watch cache if it is enabled.
return "0"
}
return lastSyncRV
return r.lastSyncResourceVersion
}
// setIsLastSyncResourceVersionExpired sets if the last list or watch request with lastSyncResourceVersion returned a
// expired error: HTTP 410 (Gone) Status Code.
func (r *Reflector) setIsLastSyncResourceVersionExpired(isExpired bool) {
r.lastSyncResourceVersionMutex.Lock()
defer r.lastSyncResourceVersionMutex.Unlock()
r.isLastSyncResourceVersionGone = isExpired
}
func isExpiredError(err error) bool {
// In Kubernetes 1.17 and earlier, the api server returns both apierrs.StatusReasonExpired and
// apierrs.StatusReasonGone for HTTP 410 (Gone) status code responses. In 1.18 the kube server is more consistent
// and always returns apierrs.StatusReasonExpired. For backward compatibility we can only remove the apierrs.IsGone
// check when we fully drop support for Kubernetes 1.17 servers from reflectors.
return apierrs.IsResourceExpired(err) || apierrs.IsGone(err)
}