Gracefully fail on legacy HC delete

controllers/gce/backends/backends.go

@@ -173,7 +173,7 @@ func (b *Backends) ensureHealthCheck(sp ServicePort) (string, error) {
 	hc := b.healthChecker.New(sp.Port, sp.Protocol)
 
 	existingLegacyHC, err := b.healthChecker.GetLegacy(sp.Port)
-	if err != nil && !utils.IsHTTPErrorCode(err, http.StatusNotFound) {
+	if err != nil && !utils.IsNotFoundError(err) {
 		return "", err
 	}
 
@@ -256,7 +256,7 @@ func (b *Backends) Add(p ServicePort) error {
 	// If previous health check was legacy type, we need to delete it.
 	if existingHCLink != hcLink && strings.Contains(existingHCLink, "/httpHealthChecks/") {
 		if err = b.healthChecker.DeleteLegacy(p.Port); err != nil {
-			return err
+			glog.Warning("Failed to delete legacy HttpHealthCheck %v; Will not try again, err: %v", pName, err)
 		}
 	}
 

controllers/gce/utils/utils.go

@@ -332,6 +332,20 @@ func IgnoreHTTPNotFound(err error) error {
 	return err
 }
 
+// IsInUsedByError returns true if the resource is being used by another GCP resource
+func IsInUsedByError(err error) bool {
+	apiErr, ok := err.(*googleapi.Error)
+	if !ok || apiErr.Code != http.StatusBadRequest {
+		return false
+	}
+	return strings.Contains(apiErr.Message, "being used by")
+}
+
+// IsNotFoundError returns true if the resource does not exist
+func IsNotFoundError(err error) bool {
+	return IsHTTPErrorCode(err, http.StatusNotFound)
+}
+
 // CompareLinks returns true if the 2 self links are equal.
 func CompareLinks(l1, l2 string) bool {
 	// TODO: These can be partial links