Documentation
¶
Overview ¶
Package retry provides configurable HTTP request retry as client middleware.
The retry middleware wraps an http.RoundTripper and automatically retries failed requests based on a configurable policy, with exponential backoff and optional jitter.
Usage ¶
mw := retry.Transport(
retry.WithMaxAttempts(3),
retry.WithBackoff(retry.ExponentialBackoff(100*time.Millisecond, 5*time.Second)),
)
transport := mw(http.DefaultTransport)
Retry-After ¶
The retry middleware respects the Retry-After response header. If a server returns 429 or 503 with Retry-After, the delay from the header overrides the backoff strategy.
Request bodies ¶
For requests with bodies to be retried, the request must have GetBody set. Use httpx.NewJSONRequest or httpx.NewFormRequest which set GetBody automatically.
Sentinel errors ¶
ErrRetryExhausted is returned when all attempts fail. The original error is wrapped and accessible via errors.Unwrap.
Index ¶
Constants ¶
This section is empty.
Variables ¶
var ErrRetryExhausted = errors.New("httpx: all retry attempts exhausted")
ErrRetryExhausted is returned when all retry attempts have been exhausted and the last attempt also failed.
Functions ¶
func ParseRetryAfter ¶
ParseRetryAfter extracts the delay from a Retry-After header (RFC 7231). It supports both the delay-seconds format ("120") and the HTTP-date format ("Fri, 31 Dec 1999 23:59:59 GMT"). Returns the duration and true if the header was present and valid; otherwise returns 0 and false.
func Transport ¶
func Transport(opts ...Option) middleware.Middleware
Transport returns a middleware that retries failed requests according to the provided options.
Types ¶
type Backoff ¶
type Backoff interface {
// Delay returns the wait duration for the given attempt number (zero-based).
Delay(attempt int) time.Duration
}
Backoff computes the delay before the next retry attempt.
func ConstantBackoff ¶
ConstantBackoff returns a Backoff that always returns the same delay.
func ExponentialBackoff ¶
ExponentialBackoff returns a Backoff that doubles the delay on each attempt. The delay is calculated as base * 2^attempt, capped at max. When withJitter is true, a random duration in [0, delay*0.5) is added.
type Option ¶
type Option func(*options)
Option configures the retry transport.
func WithBackoff ¶
WithBackoff sets the backoff strategy used to compute delays between retries.
func WithMaxAttempts ¶
WithMaxAttempts sets the maximum number of attempts (including the first). Values less than 1 are treated as 1 (no retries).
func WithPolicy ¶
WithPolicy sets the retry policy that decides whether to retry a request.
func WithRetryAfter ¶
WithRetryAfter controls whether the Retry-After response header is respected. When enabled and present, the Retry-After delay is used if it exceeds the backoff delay.
type Policy ¶
type Policy interface {
// ShouldRetry reports whether the request should be retried. The extra
// duration, if non-zero, is a policy-suggested delay that overrides the
// backoff strategy.
ShouldRetry(attempt int, req *http.Request, resp *http.Response, err error) (bool, time.Duration)
}
Policy decides whether a failed request should be retried.
Source Files