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package autorest
// Copyright 2017 Microsoft Corporation
// 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
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
import (
const (
// DefaultPollingDelay is a reasonable delay between polling requests.
DefaultPollingDelay = 60 * time.Second
// DefaultPollingDuration is a reasonable total polling duration.
DefaultPollingDuration = 15 * time.Minute
// DefaultRetryAttempts is number of attempts for retry status codes (5xx).
DefaultRetryAttempts = 3
// DefaultRetryDuration is the duration to wait between retries.
DefaultRetryDuration = 30 * time.Second
var (
// StatusCodesForRetry are a defined group of status code for which the client will retry
StatusCodesForRetry = []int{
http.StatusRequestTimeout, // 408
http.StatusTooManyRequests, // 429
http.StatusInternalServerError, // 500
http.StatusBadGateway, // 502
http.StatusServiceUnavailable, // 503
http.StatusGatewayTimeout, // 504
const (
requestFormat = `HTTP Request Begin ===================================================
===================================================== HTTP Request End
responseFormat = `HTTP Response Begin ===================================================
===================================================== HTTP Response End
// Response serves as the base for all responses from generated clients. It provides access to the
// last http.Response.
type Response struct {
*http.Response `json:"-"`
// IsHTTPStatus returns true if the returned HTTP status code matches the provided status code.
// If there was no response (i.e. the underlying http.Response is nil) the return value is false.
func (r Response) IsHTTPStatus(statusCode int) bool {
if r.Response == nil {
return false
return r.Response.StatusCode == statusCode
// HasHTTPStatus returns true if the returned HTTP status code matches one of the provided status codes.
// If there was no response (i.e. the underlying http.Response is nil) or not status codes are provided
// the return value is false.
func (r Response) HasHTTPStatus(statusCodes bool {
return ResponseHasStatusCode(r.Response, statusCodes...)
// LoggingInspector implements request and response inspectors that log the full request and
// response to a supplied log.
type LoggingInspector struct {
Logger *log.Logger
// WithInspection returns a PrepareDecorator that emits the http.Request to the supplied logger. The
// body is restored after being emitted.
// Note: Since it reads the entire Body, this decorator should not be used where body streaming is
// important. It is best used to trace JSON or similar body values.
func (li LoggingInspector) WithInspection() PrepareDecorator {
return func(p Preparer) Preparer {
return PreparerFunc(func(r *http.Request) (*http.Request, error) {
var body, b bytes.Buffer
defer r.Body.Close()
r.Body = ioutil.NopCloser(io.TeeReader(r.Body, &body))
if err := r.Write(&b); err != nil {
return nil, fmt.Errorf("Failed to write response: %v", err)
li.Logger.Printf(requestFormat, b.String())
r.Body = ioutil.NopCloser(&body)
return p.Prepare(r)
// ByInspecting returns a RespondDecorator that emits the http.Response to the supplied logger. The
// body is restored after being emitted.
// Note: Since it reads the entire Body, this decorator should not be used where body streaming is
// important. It is best used to trace JSON or similar body values.
func (li LoggingInspector) ByInspecting() RespondDecorator {
return func(r Responder) Responder {
return ResponderFunc(func(resp *http.Response) error {
var body, b bytes.Buffer
defer resp.Body.Close()
resp.Body = ioutil.NopCloser(io.TeeReader(resp.Body, &body))
if err := resp.Write(&b); err != nil {
return fmt.Errorf("Failed to write response: %v", err)
li.Logger.Printf(responseFormat, b.String())
resp.Body = ioutil.NopCloser(&body)
return r.Respond(resp)
// Client is the base for autorest generated clients. It provides default, "do nothing"
// implementations of an Authorizer, RequestInspector, and ResponseInspector. It also returns the
// standard, undecorated http.Client as a default Sender.
// Generated clients should also use Error (see NewError and NewErrorWithError) for errors and
// return responses that compose with Response.
// Most customization of generated clients is best achieved by supplying a custom Authorizer, custom
// RequestInspector, and / or custom ResponseInspector. Users may log requests, implement circuit
// breakers (see or otherwise influence
// sending the request by providing a decorated Sender.
type Client struct {
Authorizer Authorizer
Sender Sender
RequestInspector PrepareDecorator
ResponseInspector RespondDecorator
// PollingDelay sets the polling frequency used in absence of a Retry-After HTTP header
PollingDelay time.Duration
// PollingDuration sets the maximum polling time after which an error is returned.
// Setting this to zero will use the provided context to control the duration.
PollingDuration time.Duration
// RetryAttempts sets the default number of retry attempts for client.
RetryAttempts int
// RetryDuration sets the delay duration for retries.
RetryDuration time.Duration
// UserAgent, if not empty, will be set as the HTTP User-Agent header on all requests sent
// through the Do method.
UserAgent string
Jar http.CookieJar
// Set to true to skip attempted registration of resource providers (false by default).
SkipResourceProviderRegistration bool
// NewClientWithUserAgent returns an instance of a Client with the UserAgent set to the passed
// string.
func NewClientWithUserAgent(ua string) Client {
return newClient(ua, tls.RenegotiateNever)
// ClientOptions contains various Client configuration options.
type ClientOptions struct {
// UserAgent is an optional user-agent string to append to the default user agent.
UserAgent string
// Renegotiation is an optional setting to control client-side TLS renegotiation.
Renegotiation tls.RenegotiationSupport
// NewClientWithOptions returns an instance of a Client with the specified values.
func NewClientWithOptions(options ClientOptions) Client {
return newClient(options.UserAgent, options.Renegotiation)
func newClient(ua string, renegotiation tls.RenegotiationSupport) Client {
c := Client{
PollingDelay: DefaultPollingDelay,
PollingDuration: DefaultPollingDuration,
RetryAttempts: DefaultRetryAttempts,
RetryDuration: DefaultRetryDuration,
UserAgent: UserAgent(),
c.Sender = c.sender(renegotiation)
return c
// AddToUserAgent adds an extension to the current user agent
func (c *Client) AddToUserAgent(extension string) error {
if extension != "" {
c.UserAgent = fmt.Sprintf("%s %s", c.UserAgent, extension)
return nil
return fmt.Errorf("Extension was empty, User Agent stayed as %s", c.UserAgent)
// Do implements the Sender interface by invoking the active Sender after applying authorization.
// If Sender is not set, it uses a new instance of http.Client. In both cases it will, if UserAgent
// is set, apply set the User-Agent header.
func (c Client) Do(r *http.Request) (*http.Response, error) {
if r.UserAgent() == "" {
r, _ = Prepare(r,
// NOTE: c.WithInspection() must be last in the list so that it can inspect all preceding operations
r, err := Prepare(r,
if err != nil {
var resp *http.Response
if detErr, ok := err.(DetailedError); ok {
// if the authorization failed (e.g. invalid credentials) there will
// be a response associated with the error, be sure to return it.
resp = detErr.Response
return resp, NewErrorWithError(err, "autorest/Client", "Do", nil, "Preparing request failed")
logger.Instance.WriteRequest(r, logger.Filter{
Header: func(k string, v []string) (bool, []string) {
// remove the auth token from the log
if strings.EqualFold(k, "Authorization") || strings.EqualFold(k, "Ocp-Apim-Subscription-Key") {
v = []string{"**REDACTED**"}
return true, v
resp, err := SendWithSender(c.sender(tls.RenegotiateNever), r)
logger.Instance.WriteResponse(resp, logger.Filter{})
Respond(resp, c.ByInspecting())
return resp, err
// sender returns the Sender to which to send requests.
func (c Client) sender(renengotiation tls.RenegotiationSupport) Sender {
if c.Sender == nil {
// Use behaviour compatible with DefaultTransport, but require TLS minimum version.
var defaultTransport = http.DefaultTransport.(*http.Transport)
transport := tracing.Transport
// for non-default values of TLS renegotiation create a new tracing transport.
// updating tracing.Transport affects all clients which is not what we want.
if renengotiation != tls.RenegotiateNever {
transport = tracing.NewTransport()
transport.Base = &http.Transport{
Proxy: defaultTransport.Proxy,
DialContext: defaultTransport.DialContext,
MaxIdleConns: defaultTransport.MaxIdleConns,
IdleConnTimeout: defaultTransport.IdleConnTimeout,
TLSHandshakeTimeout: defaultTransport.TLSHandshakeTimeout,
ExpectContinueTimeout: defaultTransport.ExpectContinueTimeout,
TLSClientConfig: &tls.Config{
MinVersion: tls.VersionTLS12,
Renegotiation: renengotiation,
j, _ := cookiejar.New(nil)
return &http.Client{Jar: j, Transport: transport}
return c.Sender
// WithAuthorization is a convenience method that returns the WithAuthorization PrepareDecorator
// from the current Authorizer. If not Authorizer is set, it uses the NullAuthorizer.
func (c Client) WithAuthorization() PrepareDecorator {
return c.authorizer().WithAuthorization()
// authorizer returns the Authorizer to use.
func (c Client) authorizer() Authorizer {
if c.Authorizer == nil {
return NullAuthorizer{}
return c.Authorizer
// WithInspection is a convenience method that passes the request to the supplied RequestInspector,
// if present, or returns the WithNothing PrepareDecorator otherwise.
func (c Client) WithInspection() PrepareDecorator {
if c.RequestInspector == nil {
return WithNothing()
return c.RequestInspector
// ByInspecting is a convenience method that passes the response to the supplied ResponseInspector,
// if present, or returns the ByIgnoring RespondDecorator otherwise.
func (c Client) ByInspecting() RespondDecorator {
if c.ResponseInspector == nil {
return ByIgnoring()
return c.ResponseInspector
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