Repository: knative/client
Pull request #701 (2020-03-04 19:48:00)

fix(wait): Only use MODIFIED events when waiting for Read == True

knative-prow-robot: [APPROVALNOTIFIER] This PR is **APPROVED**

This pull-request has been approved by: *<a href="https://github.com/knative/client/pull/701#" title="Author self-approved">rhuss</a>*

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<details >
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- ~~[OWNERS](https://github.com/knative/client/blob/master/OWNERS)~~ [rhuss]

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knative-metrics-robot: The following is the coverage report on the affected files.
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File | Old Coverage | New Coverage | Delta
---- |:------------:|:------------:|:-----:
[pkg/wait/wait_for_ready.go](https://storage.cloud.google.com/knative-prow/pr-logs/pull/knative_client/701/pull-knative-client-go-coverage/1235290974826008576/artifacts/line-cov.html#file1) | 77.6% | 77.9% | 0.2

knative-prow-robot: [APPROVALNOTIFIER] This PR is **APPROVED**

This pull-request has been approved by: *<a href="https://github.com/knative/client/pull/701#pullrequestreview-369142158" title="LGTM">maximilien</a>*, *<a href="https://github.com/knative/client/pull/701#" title="Author self-approved">rhuss</a>*

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<details >
Needs approval from an approver in each of these files:

- ~~[OWNERS](https://github.com/knative/client/blob/master/OWNERS)~~ [maximilien,rhuss]

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Patch:
diff --git a/pkg/serving/v1/client.go b/pkg/serving/v1/client.go
index 003199be..a4bb53a1 100644
--- a/pkg/serving/v1/client.go
+++ b/pkg/serving/v1/client.go
@@ -267,7 +267,7 @@ func (cl *knServingClient) DeleteService(serviceName string, timeout time.Durati
 	waitC := make(chan error)
 	go func() {
 		waitForEvent := wait.NewWaitForEvent("service", cl.WatchService, func(evt *watch.Event) bool { return evt.Type == watch.Deleted })
-		err, _ := waitForEvent.Wait(serviceName, timeout, wait.NoopMessageCallback())
+		err, _ := waitForEvent.Wait(serviceName, wait.Options{Timeout: &timeout}, wait.NoopMessageCallback())
 		waitC <- err
 	}()
 	err := cl.deleteService(serviceName, v1.DeletePropagationForeground)
@@ -292,7 +292,7 @@ func (cl *knServingClient) deleteService(serviceName string, propagationPolicy v
 // Wait for a service to become ready, but not longer than provided timeout
 func (cl *knServingClient) WaitForService(name string, timeout time.Duration, msgCallback wait.MessageCallback) (error, time.Duration) {
 	waitForReady := wait.NewWaitForReady("service", cl.WatchService, serviceConditionExtractor)
-	return waitForReady.Wait(name, timeout, msgCallback)
+	return waitForReady.Wait(name, wait.Options{Timeout: &timeout}, msgCallback)
 }
 
 // Get the configuration for a service
@@ -382,7 +382,7 @@ func (cl *knServingClient) DeleteRevision(name string, timeout time.Duration) er
 	waitC := make(chan error)
 	go func() {
 		waitForEvent := wait.NewWaitForEvent("revision", cl.WatchRevision, func(evt *watch.Event) bool { return evt.Type == watch.Deleted })
-		err, _ := waitForEvent.Wait(name, timeout, wait.NoopMessageCallback())
+		err, _ := waitForEvent.Wait(name, wait.Options{Timeout: &timeout}, wait.NoopMessageCallback())
 		waitC <- err
 	}()
 	err := cl.deleteRevision(name)
diff --git a/pkg/wait/wait_for_ready.go b/pkg/wait/wait_for_ready.go
index 479b5439..52a50c4c 100644
--- a/pkg/wait/wait_for_ready.go
+++ b/pkg/wait/wait_for_ready.go
@@ -25,10 +25,6 @@ import (
 	"knative.dev/pkg/apis"
 )
 
-// Window for how long a ReadyCondition == false has to stay
-// for being considered as an error
-var ErrorWindow = 2 * time.Second
-
 // Callbacks and configuration used while waiting
 type waitForReadyConfig struct {
 	watchMaker          WatchMaker
@@ -50,10 +46,19 @@ type EventDone func(ev *watch.Event) bool
 // state in its "Ready" condition.
 type Wait interface {
 
-	// Wait on resource the resource with this name until a given timeout
+	// Wait on resource the resource with this name
 	// and write event messages for unknown event to the status writer.
 	// Returns an error (if any) and the overall time it took to wait
-	Wait(name string, timeout time.Duration, msgCallback MessageCallback) (error, time.Duration)
+	Wait(name string, options Options, msgCallback MessageCallback) (error, time.Duration)
+}
+
+type Options struct {
+	// Window for how long a ReadyCondition == false has to stay
+	// for being considered as an error (useful for flaky reconciliation
+	ErrorWindow *time.Duration
+
+	// Timeout for how long to wait at maximum
+	Timeout *time.Duration
 }
 
 // Create watch which is used when waiting for Ready condition
@@ -65,7 +70,7 @@ type ConditionsExtractor func(obj runtime.Object) (apis.Conditions, error)
 // Callback for event messages
 type MessageCallback func(durationSinceState time.Duration, message string)
 
-// Constructor with resource type specific configuration
+// NewWaitForReady waits until the condition is set to Ready == True
 func NewWaitForReady(kind string, watchMaker WatchMaker, extractor ConditionsExtractor) Wait {
 	return &waitForReadyConfig{
 		kind:                kind,
@@ -74,6 +79,8 @@ func NewWaitForReady(kind string, watchMaker WatchMaker, extractor ConditionsExt
 	}
 }
 
+// NewWaitForEvent creates a Wait object which waits until a specific event (i.e. when
+// the EventDone function returns true)
 func NewWaitForEvent(kind string, watchMaker WatchMaker, eventDone EventDone) Wait {
 	return &waitForEvent{
 		kind:       kind,
@@ -82,7 +89,7 @@ func NewWaitForEvent(kind string, watchMaker WatchMaker, eventDone EventDone) Wa
 	}
 }
 
-// A simple message callback which prints out messages line by line
+// SimpleMessageCallback returns a callback which prints out a simple event message to a given writer
 func SimpleMessageCallback(out io.Writer) MessageCallback {
 	oldMessage := ""
 	return func(duration time.Duration, message string) {
@@ -95,7 +102,7 @@ func SimpleMessageCallback(out io.Writer) MessageCallback {
 	}
 }
 
-// Noop-callback
+// NoopMessageCallback is callback which does nothing
 func NoopMessageCallback() MessageCallback {
 	return func(durationSinceState time.Duration, message string) {}
 }
@@ -105,12 +112,13 @@ func NoopMessageCallback() MessageCallback {
 // (e.g. "service"), `timeout` is a timeout after which the watch should be cancelled if no
 // target state has been entered yet and `out` is used for printing out status messages
 // msgCallback gets called for every event with an 'Ready' condition == UNKNOWN with the event's message.
-func (w *waitForReadyConfig) Wait(name string, timeout time.Duration, msgCallback MessageCallback) (error, time.Duration) {
+func (w *waitForReadyConfig) Wait(name string, options Options, msgCallback MessageCallback) (error, time.Duration) {
 
+	timeout := options.timeoutWithDefault()
 	floatingTimeout := timeout
 	for {
 		start := time.Now()
-		retry, timeoutReached, err := w.waitForReadyCondition(start, name, floatingTimeout, ErrorWindow, msgCallback)
+		retry, timeoutReached, err := w.waitForReadyCondition(start, name, floatingTimeout, options.errorWindowWithDefault(), msgCallback)
 		if err != nil {
 			return err, time.Since(start)
 		}
@@ -158,8 +166,22 @@ func (w *waitForReadyConfig) waitForReadyCondition(start time.Time, name string,
 				return true, false, nil
 			}
 
+			// Skip event if its not a MODIFIED event, as only MODIFIED events update the condition
+			// we are looking for.
+			// This will filter out all synthetic ADDED events that created bt the API server for
+			// the initial state. See https://kubernetes.io/docs/reference/using-api/api-concepts/#the-resourceversion-parameter
+			// for details:
+			// "Get State and Start at Most Recent: Start a watch at the most recent resource version,
+			//  which must be consistent (i.e. served from etcd via a quorum read). To establish initial state,
+			//  the watch begins with synthetic “Added” events of all resources instances that exist at the starting
+			//  resource version. All following watch events are for all changes that occurred after the resource
+			//  version the watch started at."
+			if event.Type != watch.Modified {
+				continue
+			}
+
 			// Skip event if generations has not yet been consolidated
-			inSync, err := isGivenEqualsObservedGeneration(event.Object)
+			inSync, err := generationCheck(event.Object)
 			if err != nil {
 				return false, false, err
 			}
@@ -198,7 +220,8 @@ func (w *waitForReadyConfig) waitForReadyCondition(start time.Time, name string,
 }
 
 // Wait until the expected EventDone is satisfied
-func (w *waitForEvent) Wait(name string, timeout time.Duration, msgCallback MessageCallback) (error, time.Duration) {
+func (w *waitForEvent) Wait(name string, options Options, msgCallback MessageCallback) (error, time.Duration) {
+	timeout := options.timeoutWithDefault()
 	watcher, err := w.watchMaker(name, timeout)
 	if err != nil {
 		return err, 0
@@ -223,7 +246,7 @@ func (w *waitForEvent) Wait(name string, timeout time.Duration, msgCallback Mess
 	}
 }
 
-func isGivenEqualsObservedGeneration(object runtime.Object) (bool, error) {
+func generationCheck(object runtime.Object) (bool, error) {
 	unstructured, err := runtime.DefaultUnstructuredConverter.ToUnstructured(object)
 	if err != nil {
 		return false, err
@@ -247,3 +270,17 @@ func isGivenEqualsObservedGeneration(object runtime.Object) (bool, error) {
 	}
 	return givenGeneration == observedGeneration, nil
 }
+
+func (o Options) timeoutWithDefault() time.Duration {
+	if o.Timeout != nil {
+		return *o.Timeout
+	}
+	return 60 * time.Second
+}
+
+func (o Options) errorWindowWithDefault() time.Duration {
+	if o.ErrorWindow != nil {
+		return *o.ErrorWindow
+	}
+	return 2 * time.Second
+}


Test patch:
diff --git a/pkg/wait/wait_for_ready_test.go b/pkg/wait/wait_for_ready_test.go
index cf1ebdde..7c376051 100644
--- a/pkg/wait/wait_for_ready_test.go
+++ b/pkg/wait/wait_for_ready_test.go
@@ -49,7 +49,7 @@ func TestAddWaitForReady(t *testing.T) {
 			})
 		fakeWatchApi.Start()
 		var msgs []string
-		err, _ := waitForReady.Wait("foobar", tc.timeout, func(_ time.Duration, msg string) {
+		err, _ := waitForReady.Wait("foobar", Options{Timeout: &tc.timeout}, func(_ time.Duration, msg string) {
 			msgs = append(msgs, msg)
 		})
 		close(fakeWatchApi.eventChan)
@@ -88,7 +88,7 @@ func TestAddWaitForDelete(t *testing.T) {
 			func(evt *watch.Event) bool { return evt.Type == watch.Deleted })
 		fakeWatchAPI.Start()
 
-		err, _ := waitForEvent.Wait("foobar", tc.timeout, NoopMessageCallback())
+		err, _ := waitForEvent.Wait("foobar", Options{Timeout: &tc.timeout}, NoopMessageCallback())
 		close(fakeWatchAPI.eventChan)
 
 		if tc.errorText == "" && err != nil {
@@ -106,7 +106,6 @@ func TestAddWaitForDelete(t *testing.T) {
 		if fakeWatchAPI.StopCalled != 1 {
 			t.Errorf("%d: Exactly one 'stop' should be called, but got %d", i, fakeWatchAPI.StopCalled)
 		}
-
 	}
 }
 
@@ -130,7 +129,7 @@ func prepareDeleteTestCases(name string) []waitForReadyTestCase {
 
 func errorTest(name string) waitForReadyTestCase {
 	events := []watch.Event{
-		{watch.Added, CreateTestServiceWithConditions(name, corev1.ConditionUnknown, corev1.ConditionUnknown, "", "msg1")},
+		{watch.Modified, CreateTestServiceWithConditions(name, corev1.ConditionUnknown, corev1.ConditionUnknown, "", "msg1")},
 		{watch.Modified, CreateTestServiceWithConditions(name, corev1.ConditionFalse, corev1.ConditionTrue, "FakeError", "Test Error")},
 	}
 
@@ -164,6 +163,7 @@ func peNormal(name string) ([]watch.Event, int) {
 	messages := pMessages(2)
 	return []watch.Event{
 		{watch.Added, CreateTestServiceWithConditions(name, corev1.ConditionUnknown, corev1.ConditionUnknown, "", messages[0])},
+		{watch.Modified, CreateTestServiceWithConditions(name, corev1.ConditionUnknown, corev1.ConditionUnknown, "", messages[0])},
 		{watch.Modified, CreateTestServiceWithConditions(name, corev1.ConditionUnknown, corev1.ConditionTrue, "", messages[1])},
 		{watch.Modified, CreateTestServiceWithConditions(name, corev1.ConditionTrue, corev1.ConditionTrue, "", "")},
 	}, len(messages)
@@ -172,14 +172,14 @@ func peNormal(name string) ([]watch.Event, int) {
 func peTimeout(name string) ([]watch.Event, int) {
 	messages := pMessages(1)
 	return []watch.Event{
-		{watch.Added, CreateTestServiceWithConditions(name, corev1.ConditionUnknown, corev1.ConditionUnknown, "", messages[0])},
+		{watch.Modified, CreateTestServiceWithConditions(name, corev1.ConditionUnknown, corev1.ConditionUnknown, "", messages[0])},
 	}, len(messages)
 }
 
 func peWrongGeneration(name string) ([]watch.Event, int) {
 	messages := pMessages(1)
 	return []watch.Event{
-		{watch.Added, CreateTestServiceWithConditions(name, corev1.ConditionUnknown, corev1.ConditionUnknown, "", messages[0])},
+		{watch.Modified, CreateTestServiceWithConditions(name, corev1.ConditionUnknown, corev1.ConditionUnknown, "", messages[0])},
 		{watch.Modified, CreateTestServiceWithConditions(name, corev1.ConditionTrue, corev1.ConditionTrue, "", "", 1, 2)},
 	}, len(messages)
 }
@@ -187,7 +187,7 @@ func peWrongGeneration(name string) ([]watch.Event, int) {
 func peReadyFalseWithinErrorWindow(name string) ([]watch.Event, int) {
 	messages := pMessages(1)
 	return []watch.Event{
-		{watch.Added, CreateTestServiceWithConditions(name, corev1.ConditionFalse, corev1.ConditionFalse, "Route not ready", messages[0])},
+		{watch.Modified, CreateTestServiceWithConditions(name, corev1.ConditionFalse, corev1.ConditionFalse, "Route not ready", messages[0])},
 		{watch.Modified, CreateTestServiceWithConditions(name, corev1.ConditionTrue, corev1.ConditionTrue, "Route ready", "")},
 	}, len(messages)
 }
@@ -195,7 +195,7 @@ func peReadyFalseWithinErrorWindow(name string) ([]watch.Event, int) {
 func deNormal(name string) ([]watch.Event, int) {
 	messages := pMessages(2)
 	return []watch.Event{
-		{watch.Added, CreateTestServiceWithConditions(name, corev1.ConditionUnknown, corev1.ConditionUnknown, "", messages[0])},
+		{watch.Modified, CreateTestServiceWithConditions(name, corev1.ConditionUnknown, corev1.ConditionUnknown, "", messages[0])},
 		{watch.Modified, CreateTestServiceWithConditions(name, corev1.ConditionUnknown, corev1.ConditionTrue, "", messages[1])},
 		{watch.Deleted, CreateTestServiceWithConditions(name, corev1.ConditionTrue, corev1.ConditionTrue, "", "")},
 	}, len(messages)