http

Documentation

Index

• func RetryReader(r io.ReadSeeker) io.ReadSeeker
• type Retry
  • func (r *Retry) Do(req *http.Request) (*http.Response, error)
  • func (r *Retry) Get(url string) (*http.Response, error)
  • func (r *Retry) Head(url string) (*http.Response, error)
  • func (r *Retry) Post(url, contentType string, body io.Reader) (*http.Response, error)
  • func (r *Retry) PostForm(url string, data url.Values) (*http.Response, error)

Functions

func RetryReader

func RetryReader(r io.ReadSeeker) io.ReadSeeker

RetryReader returns an io.ReadSeeker that can be used as request body for retryable requests via Seek(0, io.SeekStart). The returned io.ReadSeeker implements io.Closer.

If r does not implement io.Closer RetryReader returns an io.ReadSeeker that implements io.Closer as nop.

Types

type Retry

type Retry struct {
	// Client is the underlying HTTP client.
	// Using Client directly bypasses the
	// retry mechanism.
	http.Client

	// N is the number of retry attempts. If a request
	// fails because of a temporary network error or
	// 5xx response code then Retry keeps sending the
	// same request N times before giving up and returning
	// the last error encountered.
	N uint

	// Delay is the duration Retry waits at least before
	// retrying a request.
	Delay time.Duration

	// Jitter is the maximum duration Retry adds to Delay.
	// Retry waits at most Delay + Jitter before retrying
	// a request.
	//
	// In particular, Retry chooses a pseudo-random
	// duration [0, Jitter) and adds it do Delay.
	Jitter time.Duration
}

Retry wraps an HTTP client and retries requests when they fail because of a temporary network error or a 5xx response status code.

Its zero value is a usable client that uses http.DefaultTransport and may retry a request a few times before giving up.

If a request contains a non-nil body then this body must implement io.Seeker. Any io.ReadSeeker can be turned into a request body via the RetryReader function.

Retry retries a request at most N times and waits at least Delay and at most Delay + Jitter before sending the request again. If not specified then Retry uses sane default values for N, Delay and Jitter.

func (*Retry) Do

func (r *Retry) Do(req *http.Request) (*http.Response, error)

Do sends an HTTP request and returns an HTTP response, following policy (such as redirects, cookies, auth) as configured on the client and as specified by http.Client.

If the request fails due to a temporary network error or the server returns a 5xx response then Do retries the request N times.

If non-nil, the request body must implement io.Seeker.

Any returned error will be of type *url.Error. The url.Error value's Timeout method will report true if request timed out or was canceled.

func (*Retry) Get

func (r *Retry) Get(url string) (*http.Response, error)

Get issues a GET to the specified URL as specified by http.Client. It follows redirects after calling the underlying Client's CheckRedirect function.

If the GET fails due to a temporary network error or 5xx server response then GET retries the request N times.

func (*Retry) Head

func (r *Retry) Head(url string) (*http.Response, error)

Head issues a HEAD to the specified URL as specified by http.Client. It follows redirects after calling the underlying Client's CheckRedirect function.

If the HEAD fails due to a temporary network error or 5xx server response then Head retries the request N times.

func (*Retry) Post

func (r *Retry) Post(url, contentType string, body io.Reader) (*http.Response, error)

Post issues a POST to the specified URL as specified by http.Client. The provided body must implement io.Seeker and io.Closer. To obtain an io.Closer from an io.ReadSeeker refer to the RetryReader function.

Caller should close resp.Body when done reading from it.

If the POST fails due to a temporary network error or 5xx server response the Post retries the request N times.

See the Retry.Do method documentation for details on how redirects are handled.

func (*Retry) PostForm

func (r *Retry) PostForm(url string, data url.Values) (*http.Response, error)

PostForm issues a POST to the specified URL as specified by http.Client, with data's keys and values URL-encoded as the request body.

The Content-Type header is set to application/x-www-form-urlencoded.

If the POST fails due to a temporary network error or 5xx server response the Post retries the request N times.

See the Client.Do method documentation for details on how redirects are handled.