215 lines
8.3 KiB
Go
215 lines
8.3 KiB
Go
/*
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Copyright 2014 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package scale
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import (
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"context"
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"fmt"
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"strconv"
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"time"
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autoscalingv1 "k8s.io/api/autoscaling/v1"
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"k8s.io/apimachinery/pkg/api/errors"
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metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
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"k8s.io/apimachinery/pkg/runtime/schema"
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"k8s.io/apimachinery/pkg/types"
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"k8s.io/apimachinery/pkg/util/json"
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"k8s.io/apimachinery/pkg/util/wait"
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scaleclient "k8s.io/client-go/scale"
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)
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// Scaler provides an interface for resources that can be scaled.
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type Scaler interface {
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// Scale scales the named resource after checking preconditions. It optionally
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// retries in the event of resource version mismatch (if retry is not nil),
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// and optionally waits until the status of the resource matches newSize (if wait is not nil)
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// TODO: Make the implementation of this watch-based (#56075) once #31345 is fixed.
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Scale(namespace, name string, newSize uint, preconditions *ScalePrecondition, retry, wait *RetryParams, gvr schema.GroupVersionResource, dryRun bool) error
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// ScaleSimple does a simple one-shot attempt at scaling - not useful on its own, but
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// a necessary building block for Scale
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ScaleSimple(namespace, name string, preconditions *ScalePrecondition, newSize uint, gvr schema.GroupVersionResource, dryRun bool) (updatedResourceVersion string, err error)
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}
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// NewScaler get a scaler for a given resource
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func NewScaler(scalesGetter scaleclient.ScalesGetter) Scaler {
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return &genericScaler{scalesGetter}
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}
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// ScalePrecondition describes a condition that must be true for the scale to take place
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// If CurrentSize == -1, it is ignored.
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// If CurrentResourceVersion is the empty string, it is ignored.
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// Otherwise they must equal the values in the resource for it to be valid.
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type ScalePrecondition struct {
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Size int
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ResourceVersion string
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}
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// A PreconditionError is returned when a resource fails to match
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// the scale preconditions passed to kubectl.
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type PreconditionError struct {
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Precondition string
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ExpectedValue string
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ActualValue string
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}
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func (pe PreconditionError) Error() string {
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return fmt.Sprintf("Expected %s to be %s, was %s", pe.Precondition, pe.ExpectedValue, pe.ActualValue)
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}
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// RetryParams encapsulates the retry parameters used by kubectl's scaler.
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type RetryParams struct {
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Interval, Timeout time.Duration
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}
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func NewRetryParams(interval, timeout time.Duration) *RetryParams {
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return &RetryParams{interval, timeout}
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}
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// ScaleCondition is a closure around Scale that facilitates retries via util.wait
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func ScaleCondition(r Scaler, precondition *ScalePrecondition, namespace, name string, count uint, updatedResourceVersion *string, gvr schema.GroupVersionResource, dryRun bool) wait.ConditionFunc {
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return func() (bool, error) {
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rv, err := r.ScaleSimple(namespace, name, precondition, count, gvr, dryRun)
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if updatedResourceVersion != nil {
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*updatedResourceVersion = rv
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}
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// Retry only on update conflicts.
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if errors.IsConflict(err) {
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return false, nil
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}
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if err != nil {
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return false, err
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}
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return true, nil
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}
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}
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// validateGeneric ensures that the preconditions match. Returns nil if they are valid, otherwise an error
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func (precondition *ScalePrecondition) validate(scale *autoscalingv1.Scale) error {
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if precondition.Size != -1 && int(scale.Spec.Replicas) != precondition.Size {
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return PreconditionError{"replicas", strconv.Itoa(precondition.Size), strconv.Itoa(int(scale.Spec.Replicas))}
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}
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if len(precondition.ResourceVersion) > 0 && scale.ResourceVersion != precondition.ResourceVersion {
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return PreconditionError{"resource version", precondition.ResourceVersion, scale.ResourceVersion}
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}
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return nil
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}
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// genericScaler can update scales for resources in a particular namespace
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type genericScaler struct {
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scaleNamespacer scaleclient.ScalesGetter
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}
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var _ Scaler = &genericScaler{}
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// ScaleSimple updates a scale of a given resource. It returns the resourceVersion of the scale if the update was successful.
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func (s *genericScaler) ScaleSimple(namespace, name string, preconditions *ScalePrecondition, newSize uint, gvr schema.GroupVersionResource, dryRun bool) (updatedResourceVersion string, err error) {
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if preconditions != nil {
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scale, err := s.scaleNamespacer.Scales(namespace).Get(context.TODO(), gvr.GroupResource(), name, metav1.GetOptions{})
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if err != nil {
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return "", err
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}
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if err = preconditions.validate(scale); err != nil {
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return "", err
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}
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scale.Spec.Replicas = int32(newSize)
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updateOptions := metav1.UpdateOptions{}
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if dryRun {
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updateOptions.DryRun = []string{metav1.DryRunAll}
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}
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updatedScale, err := s.scaleNamespacer.Scales(namespace).Update(context.TODO(), gvr.GroupResource(), scale, updateOptions)
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if err != nil {
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return "", err
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}
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return updatedScale.ResourceVersion, nil
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}
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// objectForReplicas is used for encoding scale patch
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type objectForReplicas struct {
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Replicas uint `json:"replicas"`
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}
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// objectForSpec is used for encoding scale patch
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type objectForSpec struct {
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Spec objectForReplicas `json:"spec"`
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}
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spec := objectForSpec{
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Spec: objectForReplicas{Replicas: newSize},
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}
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patch, err := json.Marshal(&spec)
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if err != nil {
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return "", err
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}
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patchOptions := metav1.PatchOptions{}
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if dryRun {
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patchOptions.DryRun = []string{metav1.DryRunAll}
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}
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updatedScale, err := s.scaleNamespacer.Scales(namespace).Patch(context.TODO(), gvr, name, types.MergePatchType, patch, patchOptions)
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if err != nil {
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return "", err
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}
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return updatedScale.ResourceVersion, nil
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}
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// Scale updates a scale of a given resource to a new size, with optional precondition check (if preconditions is not nil),
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// optional retries (if retry is not nil), and then optionally waits for the status to reach desired count.
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func (s *genericScaler) Scale(namespace, resourceName string, newSize uint, preconditions *ScalePrecondition, retry, waitForReplicas *RetryParams, gvr schema.GroupVersionResource, dryRun bool) error {
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if retry == nil {
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// make it try only once, immediately
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retry = &RetryParams{Interval: time.Millisecond, Timeout: time.Millisecond}
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}
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cond := ScaleCondition(s, preconditions, namespace, resourceName, newSize, nil, gvr, dryRun)
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if err := wait.PollImmediate(retry.Interval, retry.Timeout, cond); err != nil {
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return err
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}
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if waitForReplicas != nil {
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return WaitForScaleHasDesiredReplicas(s.scaleNamespacer, gvr.GroupResource(), resourceName, namespace, newSize, waitForReplicas)
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}
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return nil
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}
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// scaleHasDesiredReplicas returns a condition that will be true if and only if the desired replica
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// count for a scale (Spec) equals its updated replicas count (Status)
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func scaleHasDesiredReplicas(sClient scaleclient.ScalesGetter, gr schema.GroupResource, resourceName string, namespace string, desiredReplicas int32) wait.ConditionFunc {
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return func() (bool, error) {
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actualScale, err := sClient.Scales(namespace).Get(context.TODO(), gr, resourceName, metav1.GetOptions{})
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if err != nil {
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return false, err
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}
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// this means the desired scale target has been reset by something else
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if actualScale.Spec.Replicas != desiredReplicas {
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return true, nil
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}
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return actualScale.Spec.Replicas == actualScale.Status.Replicas &&
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desiredReplicas == actualScale.Status.Replicas, nil
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}
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}
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// WaitForScaleHasDesiredReplicas waits until condition scaleHasDesiredReplicas is satisfied
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// or returns error when timeout happens
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func WaitForScaleHasDesiredReplicas(sClient scaleclient.ScalesGetter, gr schema.GroupResource, resourceName string, namespace string, newSize uint, waitForReplicas *RetryParams) error {
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if waitForReplicas == nil {
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return fmt.Errorf("waitForReplicas parameter cannot be nil")
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}
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err := wait.PollImmediate(
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waitForReplicas.Interval,
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waitForReplicas.Timeout,
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scaleHasDesiredReplicas(sClient, gr, resourceName, namespace, int32(newSize)))
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if err == wait.ErrWaitTimeout {
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return fmt.Errorf("timed out waiting for %q to be synced", resourceName)
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}
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return err
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}
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