Add backoff retry which implements autorest.SendDecorator interface

This commit is contained in:
Pengfei Ni 2019-12-30 04:49:00 +00:00
parent 210f1a904d
commit 7382a7c801
6 changed files with 424 additions and 18 deletions

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@ -2,18 +2,31 @@ load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
go_library(
name = "go_default_library",
srcs = ["azure_error.go"],
srcs = [
"azure_error.go",
"azure_retry.go",
"doc.go",
],
importmap = "k8s.io/kubernetes/vendor/k8s.io/legacy-cloud-providers/azure/retry",
importpath = "k8s.io/legacy-cloud-providers/azure/retry",
visibility = ["//visibility:public"],
deps = ["//vendor/k8s.io/klog:go_default_library"],
deps = [
"//vendor/github.com/Azure/go-autorest/autorest:go_default_library",
"//vendor/k8s.io/klog:go_default_library",
],
)
go_test(
name = "go_default_test",
srcs = ["azure_error_test.go"],
srcs = [
"azure_error_test.go",
"azure_retry_test.go",
],
embed = [":go_default_library"],
deps = ["//vendor/github.com/stretchr/testify/assert:go_default_library"],
deps = [
"//vendor/github.com/Azure/go-autorest/autorest/mocks:go_default_library",
"//vendor/github.com/stretchr/testify/assert:go_default_library",
],
)
filegroup(

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@ -19,7 +19,9 @@ limitations under the License.
package retry
import (
"bytes"
"fmt"
"io/ioutil"
"net/http"
"strconv"
"strings"
@ -28,6 +30,11 @@ import (
"k8s.io/klog"
)
const (
// RetryAfterHeaderKey is the retry-after header key in ARM responses.
RetryAfterHeaderKey = "Retry-After"
)
var (
// The function to get current time.
now = time.Now
@ -57,6 +64,15 @@ func (err *Error) Error() error {
err.Retriable, err.RetryAfter.String(), err.HTTPStatusCode, err.RawError)
}
// IsThrottled returns true the if the request is being throttled.
func (err *Error) IsThrottled() bool {
if err == nil {
return false
}
return err.HTTPStatusCode == http.StatusTooManyRequests || err.RetryAfter.After(now())
}
// NewError creates a new Error.
func NewError(retriable bool, err error) *Error {
return &Error{
@ -73,6 +89,20 @@ func GetRetriableError(err error) *Error {
}
}
// GetRateLimitError creates a new error for rate limiting.
func GetRateLimitError(isWrite bool, opName string) *Error {
opType := "read"
if isWrite {
opType = "write"
}
return GetRetriableError(fmt.Errorf("azure cloud provider rate limited(%s) for operation %q", opType, opName))
}
// GetThrottlingError creates a new error for throttling.
func GetThrottlingError(operation, reason string) *Error {
return GetRetriableError(fmt.Errorf("azure cloud provider throttled for operation %s with reason %q", operation, reason))
}
// GetError gets a new Error based on resp and error.
func GetError(resp *http.Response, err error) *Error {
if err == nil && resp == nil {
@ -88,12 +118,8 @@ func GetError(resp *http.Response, err error) *Error {
if retryAfterDuration := getRetryAfter(resp); retryAfterDuration != 0 {
retryAfter = now().Add(retryAfterDuration)
}
rawError := err
if err == nil && resp != nil {
rawError = fmt.Errorf("HTTP response: %v", resp.StatusCode)
}
return &Error{
RawError: rawError,
RawError: getRawError(resp, err),
RetryAfter: retryAfter,
Retriable: shouldRetryHTTPRequest(resp, err),
HTTPStatusCode: getHTTPStatusCode(resp),
@ -114,6 +140,27 @@ func isSuccessHTTPResponse(resp *http.Response) bool {
return false
}
func getRawError(resp *http.Response, err error) error {
if err != nil {
return err
}
if resp == nil || resp.Body == nil {
return fmt.Errorf("empty HTTP response")
}
// return the http status if unabled to get response body.
defer resp.Body.Close()
respBody, _ := ioutil.ReadAll(resp.Body)
resp.Body = ioutil.NopCloser(bytes.NewReader(respBody))
if len(respBody) == 0 {
return fmt.Errorf("HTTP status code (%d)", resp.StatusCode)
}
// return the raw response body.
return fmt.Errorf("%s", string(respBody))
}
func getHTTPStatusCode(resp *http.Response) int {
if resp == nil {
return -1
@ -151,7 +198,7 @@ func getRetryAfter(resp *http.Response) time.Duration {
return 0
}
ra := resp.Header.Get("Retry-After")
ra := resp.Header.Get(RetryAfterHeaderKey)
if ra == "" {
return 0
}

View File

@ -19,7 +19,9 @@ limitations under the License.
package retry
import (
"bytes"
"fmt"
"io/ioutil"
"net/http"
"testing"
"time"
@ -44,11 +46,11 @@ func TestGetError(t *testing.T) {
},
{
code: http.StatusOK,
err: fmt.Errorf("some error"),
err: fmt.Errorf("unknown error"),
expected: &Error{
Retriable: true,
HTTPStatusCode: http.StatusOK,
RawError: fmt.Errorf("some error"),
RawError: fmt.Errorf("unknown error"),
},
},
{
@ -56,7 +58,7 @@ func TestGetError(t *testing.T) {
expected: &Error{
Retriable: false,
HTTPStatusCode: http.StatusBadRequest,
RawError: fmt.Errorf("HTTP response: 400"),
RawError: fmt.Errorf("some error"),
},
},
{
@ -64,7 +66,7 @@ func TestGetError(t *testing.T) {
expected: &Error{
Retriable: true,
HTTPStatusCode: http.StatusInternalServerError,
RawError: fmt.Errorf("HTTP response: 500"),
RawError: fmt.Errorf("some error"),
},
},
{
@ -83,7 +85,7 @@ func TestGetError(t *testing.T) {
Retriable: true,
HTTPStatusCode: http.StatusTooManyRequests,
RetryAfter: now().Add(100 * time.Second),
RawError: fmt.Errorf("HTTP response: 429"),
RawError: fmt.Errorf("some error"),
},
},
}
@ -92,6 +94,7 @@ func TestGetError(t *testing.T) {
resp := &http.Response{
StatusCode: test.code,
Header: http.Header{},
Body: ioutil.NopCloser(bytes.NewReader([]byte("some error"))),
}
if test.retryAfter != 0 {
resp.Header.Add("Retry-After", fmt.Sprintf("%d", test.retryAfter))
@ -138,7 +141,7 @@ func TestGetStatusNotFoundAndForbiddenIgnoredError(t *testing.T) {
expected: &Error{
Retriable: false,
HTTPStatusCode: http.StatusBadRequest,
RawError: fmt.Errorf("HTTP response: 400"),
RawError: fmt.Errorf("some error"),
},
},
{
@ -146,7 +149,7 @@ func TestGetStatusNotFoundAndForbiddenIgnoredError(t *testing.T) {
expected: &Error{
Retriable: true,
HTTPStatusCode: http.StatusInternalServerError,
RawError: fmt.Errorf("HTTP response: 500"),
RawError: fmt.Errorf("some error"),
},
},
{
@ -165,7 +168,7 @@ func TestGetStatusNotFoundAndForbiddenIgnoredError(t *testing.T) {
Retriable: true,
HTTPStatusCode: http.StatusTooManyRequests,
RetryAfter: now().Add(100 * time.Second),
RawError: fmt.Errorf("HTTP response: 429"),
RawError: fmt.Errorf("some error"),
},
},
}
@ -174,6 +177,7 @@ func TestGetStatusNotFoundAndForbiddenIgnoredError(t *testing.T) {
resp := &http.Response{
StatusCode: test.code,
Header: http.Header{},
Body: ioutil.NopCloser(bytes.NewReader([]byte("some error"))),
}
if test.retryAfter != 0 {
resp.Header.Add("Retry-After", fmt.Sprintf("%d", test.retryAfter))
@ -251,3 +255,38 @@ func TestIsSuccessResponse(t *testing.T) {
}
}
}
func TestIsThrottled(t *testing.T) {
tests := []struct {
err *Error
expected bool
}{
{
err: nil,
expected: false,
},
{
err: &Error{
HTTPStatusCode: http.StatusOK,
},
expected: false,
},
{
err: &Error{
HTTPStatusCode: http.StatusTooManyRequests,
},
expected: true,
},
{
err: &Error{
RetryAfter: time.Now().Add(time.Hour),
},
expected: true,
},
}
for _, test := range tests {
real := test.err.IsThrottled()
assert.Equal(t, test.expected, real)
}
}

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@ -0,0 +1,161 @@
// +build !providerless
/*
Copyright 2019 The Kubernetes Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package retry
import (
"math/rand"
"net/http"
"time"
"github.com/Azure/go-autorest/autorest"
"k8s.io/klog"
)
// Backoff holds parameters applied to a Backoff function.
type Backoff struct {
// The initial duration.
Duration time.Duration
// Duration is multiplied by factor each iteration, if factor is not zero
// and the limits imposed by Steps and Cap have not been reached.
// Should not be negative.
// The jitter does not contribute to the updates to the duration parameter.
Factor float64
// The sleep at each iteration is the duration plus an additional
// amount chosen uniformly at random from the interval between
// zero and `jitter*duration`.
Jitter float64
// The remaining number of iterations in which the duration
// parameter may change (but progress can be stopped earlier by
// hitting the cap). If not positive, the duration is not
// changed. Used for exponential backoff in combination with
// Factor and Cap.
Steps int
// A limit on revised values of the duration parameter. If a
// multiplication by the factor parameter would make the duration
// exceed the cap then the duration is set to the cap and the
// steps parameter is set to zero.
Cap time.Duration
}
// NewBackoff creates a new Backoff.
func NewBackoff(duration time.Duration, factor float64, jitter float64, steps int, cap time.Duration) *Backoff {
return &Backoff{
Duration: duration,
Factor: factor,
Jitter: jitter,
Steps: steps,
Cap: cap,
}
}
// Step (1) returns an amount of time to sleep determined by the
// original Duration and Jitter and (2) mutates the provided Backoff
// to update its Steps and Duration.
func (b *Backoff) Step() time.Duration {
if b.Steps < 1 {
if b.Jitter > 0 {
return jitter(b.Duration, b.Jitter)
}
return b.Duration
}
b.Steps--
duration := b.Duration
// calculate the next step
if b.Factor != 0 {
b.Duration = time.Duration(float64(b.Duration) * b.Factor)
if b.Cap > 0 && b.Duration > b.Cap {
b.Duration = b.Cap
b.Steps = 0
}
}
if b.Jitter > 0 {
duration = jitter(duration, b.Jitter)
}
return duration
}
// Jitter returns a time.Duration between duration and duration + maxFactor *
// duration.
//
// This allows clients to avoid converging on periodic behavior. If maxFactor
// is 0.0, a suggested default value will be chosen.
func jitter(duration time.Duration, maxFactor float64) time.Duration {
if maxFactor <= 0.0 {
maxFactor = 1.0
}
wait := duration + time.Duration(rand.Float64()*maxFactor*float64(duration))
return wait
}
// DoExponentialBackoffRetry reprents an autorest.SendDecorator with backoff retry.
func DoExponentialBackoffRetry(backoff *Backoff) autorest.SendDecorator {
return func(s autorest.Sender) autorest.Sender {
return autorest.SenderFunc(func(r *http.Request) (*http.Response, error) {
return doBackoffRetry(s, r, backoff)
})
}
}
// doBackoffRetry does the backoff retries for the request.
func doBackoffRetry(s autorest.Sender, r *http.Request, backoff *Backoff) (resp *http.Response, err error) {
rr := autorest.NewRetriableRequest(r)
// Increment to add the first call (attempts denotes number of retries)
for backoff.Steps > 0 {
err = rr.Prepare()
if err != nil {
return
}
resp, err = s.Do(rr.Request())
rerr := GetError(resp, err)
// Abort retries in the following scenarios:
// 1) request succeed
// 2) request is not retriable
// 3) request has been throttled
// 4) request has completed all the retry steps
if rerr == nil || !rerr.Retriable || rerr.IsThrottled() || backoff.Steps == 1 {
return resp, rerr.Error()
}
if !delayForBackOff(backoff, r.Context().Done()) {
if r.Context().Err() != nil {
return resp, r.Context().Err()
}
return resp, rerr.Error()
}
klog.V(3).Infof("Backoff retrying %s %q with error %v", r.Method, r.URL.String(), rerr)
}
return resp, err
}
// delayForBackOff invokes time.After for the supplied backoff duration.
// The delay may be canceled by closing the passed channel. If terminated early, returns false.
func delayForBackOff(backoff *Backoff, cancel <-chan struct{}) bool {
d := backoff.Step()
select {
case <-time.After(d):
return true
case <-cancel:
return false
}
}

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@ -0,0 +1,125 @@
// +build !providerless
/*
Copyright 2019 The Kubernetes Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package retry
import (
"fmt"
"math/rand"
"net/http"
"net/url"
"testing"
"time"
"github.com/Azure/go-autorest/autorest/mocks"
"github.com/stretchr/testify/assert"
)
func TestStep(t *testing.T) {
tests := []struct {
initial *Backoff
want []time.Duration
}{
{initial: &Backoff{Duration: time.Second, Steps: 0}, want: []time.Duration{time.Second, time.Second, time.Second}},
{initial: &Backoff{Duration: time.Second, Steps: 1}, want: []time.Duration{time.Second, time.Second, time.Second}},
{initial: &Backoff{Duration: time.Second, Factor: 1.0, Steps: 1}, want: []time.Duration{time.Second, time.Second, time.Second}},
{initial: &Backoff{Duration: time.Second, Factor: 2, Steps: 3}, want: []time.Duration{1 * time.Second, 2 * time.Second, 4 * time.Second}},
{initial: &Backoff{Duration: time.Second, Factor: 2, Steps: 3, Cap: 3 * time.Second}, want: []time.Duration{1 * time.Second, 2 * time.Second, 3 * time.Second}},
{initial: &Backoff{Duration: time.Second, Factor: 2, Steps: 2, Cap: 3 * time.Second, Jitter: 0.5}, want: []time.Duration{2 * time.Second, 3 * time.Second, 3 * time.Second}},
{initial: &Backoff{Duration: time.Second, Factor: 2, Steps: 6, Jitter: 4}, want: []time.Duration{1 * time.Second, 2 * time.Second, 4 * time.Second, 8 * time.Second, 16 * time.Second, 32 * time.Second}},
}
for seed := int64(0); seed < 5; seed++ {
for _, tt := range tests {
initial := *tt.initial
t.Run(fmt.Sprintf("%#v seed=%d", initial, seed), func(t *testing.T) {
rand.Seed(seed)
for i := 0; i < len(tt.want); i++ {
got := initial.Step()
t.Logf("[%d]=%s", i, got)
if initial.Jitter > 0 {
if got == tt.want[i] {
// this is statistically unlikely to happen by chance
t.Errorf("Backoff.Step(%d) = %v, no jitter", i, got)
continue
}
diff := float64(tt.want[i]-got) / float64(tt.want[i])
if diff > initial.Jitter {
t.Errorf("Backoff.Step(%d) = %v, want %v, outside range", i, got, tt.want)
continue
}
} else {
if got != tt.want[i] {
t.Errorf("Backoff.Step(%d) = %v, want %v", i, got, tt.want)
continue
}
}
}
})
}
}
}
func TestDoBackoffRetry(t *testing.T) {
backoff := &Backoff{Factor: 1.0, Steps: 3}
fakeRequest := &http.Request{
URL: &url.URL{
Host: "localhost",
Path: "/api",
},
}
r := mocks.NewResponseWithStatus("500 InternelServerError", http.StatusInternalServerError)
client := mocks.NewSender()
client.AppendAndRepeatResponse(r, 3)
// retries up to steps on errors
expectedErr := &Error{
Retriable: true,
HTTPStatusCode: 500,
RawError: fmt.Errorf("HTTP status code (500)"),
}
resp, err := doBackoffRetry(client, fakeRequest, backoff)
assert.NotNil(t, resp)
assert.Equal(t, 500, resp.StatusCode)
assert.Equal(t, expectedErr.Error(), err)
assert.Equal(t, 3, client.Attempts())
// returns immediately on succeed
r = mocks.NewResponseWithStatus("200 OK", http.StatusOK)
client = mocks.NewSender()
client.AppendAndRepeatResponse(r, 1)
resp, err = doBackoffRetry(client, fakeRequest, backoff)
assert.Nil(t, err)
assert.Equal(t, 1, client.Attempts())
assert.NotNil(t, resp)
assert.Equal(t, 200, resp.StatusCode)
// returns immediately on throttling
r = mocks.NewResponseWithStatus("429 TooManyRequests", http.StatusTooManyRequests)
client = mocks.NewSender()
client.AppendAndRepeatResponse(r, 1)
expectedErr = &Error{
Retriable: true,
HTTPStatusCode: 429,
RawError: fmt.Errorf("HTTP status code (429)"),
}
resp, err = doBackoffRetry(client, fakeRequest, backoff)
assert.Equal(t, expectedErr.Error(), err)
assert.Equal(t, 1, client.Attempts())
assert.NotNil(t, resp)
assert.Equal(t, 429, resp.StatusCode)
}

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@ -0,0 +1,21 @@
// +build !providerless
/*
Copyright 2019 The Kubernetes Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
// Package retry defines a general library to handle errors and retries for various
// Azure clients.
package retry // import "k8s.io/legacy-cloud-providers/azure/retry"