TTL is not preserved automatically during edit

Change the signature of GuaranteedUpdate so that TTL can
be more easily preserved. Allow a simpler (no ttl) and
more complex (response and node directly available, set ttl)
path for GuaranteedUpdate.  Add some tests to ensure this
doesn't blow up again.

pkg/registry/generic/etcd/etcd.go

@@ -72,8 +72,9 @@ type Etcd struct {
 	ObjectNameFunc func(obj runtime.Object) (string, error)
 
 	// Return the TTL objects should be persisted with. Update is true if this
-	// is an operation against an existing object.
-	TTLFunc func(obj runtime.Object, update bool) (uint64, error)
+	// is an operation against an existing object. Existing is the current TTL
+	// or the default for this operation.
+	TTLFunc func(obj runtime.Object, existing uint64, update bool) (uint64, error)
 
 	// Returns a matcher corresponding to the provided labels and fields.
 	PredicateFunc func(label labels.Selector, field fields.Selector) generic.Matcher
@@ -184,12 +185,9 @@ func (e *Etcd) CreateWithName(ctx api.Context, name string, obj runtime.Object)
 			return err
 		}
 	}
-	ttl := uint64(0)
-	if e.TTLFunc != nil {
-		ttl, err = e.TTLFunc(obj, false)
-		if err != nil {
-			return err
-		}
+	ttl, err := e.calculateTTL(obj, 0, false)
+	if err != nil {
+		return err
 	}
 	err = e.Helper.CreateObj(key, obj, nil, ttl)
 	err = etcderr.InterpretCreateError(err, e.EndpointName, name)
@@ -214,12 +212,9 @@ func (e *Etcd) Create(ctx api.Context, obj runtime.Object) (runtime.Object, erro
 	if err != nil {
 		return nil, err
 	}
-	ttl := uint64(0)
-	if e.TTLFunc != nil {
-		ttl, err = e.TTLFunc(obj, false)
-		if err != nil {
-			return nil, err
-		}
+	ttl, err := e.calculateTTL(obj, 0, false)
+	if err != nil {
+		return nil, err
 	}
 	trace.Step("About to create object")
 	out := e.NewFunc()
@@ -249,12 +244,9 @@ func (e *Etcd) UpdateWithName(ctx api.Context, name string, obj runtime.Object)
 	if err != nil {
 		return err
 	}
-	ttl := uint64(0)
-	if e.TTLFunc != nil {
-		ttl, err = e.TTLFunc(obj, true)
-		if err != nil {
-			return err
-		}
+	ttl, err := e.calculateTTL(obj, 0, true)
+	if err != nil {
+		return err
 	}
 	err = e.Helper.SetObj(key, obj, nil, ttl)
 	err = etcderr.InterpretUpdateError(err, e.EndpointName, name)
@@ -281,49 +273,46 @@ func (e *Etcd) Update(ctx api.Context, obj runtime.Object) (runtime.Object, bool
 	// TODO: expose TTL
 	creating := false
 	out := e.NewFunc()
-	err = e.Helper.GuaranteedUpdate(key, out, true, func(existing runtime.Object) (runtime.Object, uint64, error) {
+	err = e.Helper.GuaranteedUpdate(key, out, true, func(existing runtime.Object, res tools.ResponseMeta) (runtime.Object, *uint64, error) {
 		version, err := e.Helper.Versioner.ObjectResourceVersion(existing)
 		if err != nil {
-			return nil, 0, err
+			return nil, nil, err
 		}
 		if version == 0 {
 			if !e.UpdateStrategy.AllowCreateOnUpdate() {
-				return nil, 0, kubeerr.NewNotFound(e.EndpointName, name)
+				return nil, nil, kubeerr.NewNotFound(e.EndpointName, name)
 			}
 			creating = true
 			if err := rest.BeforeCreate(e.CreateStrategy, ctx, obj); err != nil {
-				return nil, 0, err
+				return nil, nil, err
 			}
-			ttl := uint64(0)
-			if e.TTLFunc != nil {
-				ttl, err = e.TTLFunc(obj, false)
-				if err != nil {
-					return nil, 0, err
-				}
+			ttl, err := e.calculateTTL(obj, 0, false)
+			if err != nil {
+				return nil, nil, err
 			}
-			return obj, ttl, nil
+			return obj, &ttl, nil
 		}
 
 		creating = false
 		newVersion, err := e.Helper.Versioner.ObjectResourceVersion(obj)
 		if err != nil {
-			return nil, 0, err
+			return nil, nil, err
 		}
 		if newVersion != version {
 			// TODO: return the most recent version to a client?
-			return nil, 0, kubeerr.NewConflict(e.EndpointName, name, fmt.Errorf("the resource was updated to %d", version))
+			return nil, nil, kubeerr.NewConflict(e.EndpointName, name, fmt.Errorf("the resource was updated to %d", version))
 		}
 		if err := rest.BeforeUpdate(e.UpdateStrategy, ctx, obj, existing); err != nil {
-			return nil, 0, err
+			return nil, nil, err
 		}
-		ttl := uint64(0)
-		if e.TTLFunc != nil {
-			ttl, err = e.TTLFunc(obj, true)
-			if err != nil {
-				return nil, 0, err
-			}
+		ttl, err := e.calculateTTL(obj, res.TTL, true)
+		if err != nil {
+			return nil, nil, err
 		}
-		return obj, ttl, nil
+		if int64(ttl) != res.TTL {
+			return obj, &ttl, nil
+		}
+		return obj, nil, nil
 	})
 
 	if err != nil {
@@ -479,3 +468,19 @@ func (e *Etcd) WatchPredicate(ctx api.Context, m generic.Matcher, resourceVersio
 
 	return e.Helper.WatchList(e.KeyRootFunc(ctx), version, filterFunc)
 }
+
+// calculateTTL is a helper for retrieving the updated TTL for an object or returning an error
+// if the TTL cannot be calculated. The defaultTTL is changed to 1 if less than zero. Zero means
+// no TTL, not expire immediately.
+func (e *Etcd) calculateTTL(obj runtime.Object, defaultTTL int64, update bool) (ttl uint64, err error) {
+	// etcd may return a negative TTL for a node if the expiration has not occured due
+	// to server lag - we will ensure that the value is at least set.
+	if defaultTTL < 0 {
+		defaultTTL = 1
+	}
+	ttl = uint64(defaultTTL)
+	if e.TTLFunc != nil {
+		ttl, err = e.TTLFunc(obj, ttl, update)
+	}
+	return ttl, err
+}