github.com/hashicorp/go-retryablehttp
Package retryablehttp provides a familiar HTTP client interface with automatic retries and exponential backoff. It is a thin wrapper over the standard net/http client library and exposes nearly the same public API. This makes retryablehttp very easy to drop into existing programs. retryablehttp performs automatic retries under certain conditions. Mainly, if an error is returned by the client (connection errors etc), or if a 500-range response is received, then a retry is invoked. Otherwise, the response is returned and left to the caller to interpret. Requests which take a request body should provide a non-nil function parameter. The best choice is to provide either a function satisfying ReaderFunc which provides multiple io.Readers in an efficient manner, a *bytes.Buffer (the underlying raw byte slice will be used) or a raw byte slice. As it is a reference type, and we will wrap it as needed by readers, we can efficiently re-use the request body without needing to copy it. If an io.Reader (such as a *bytes.Reader) is provided, the full body will be read prior to the first request, and will be efficiently re-used for any retries. ReadSeeker can be used, but some users have observed occasional data races between the net/http library and the Seek functionality of some implementations of ReadSeeker, so should be avoided if possible.
Readme
The retryablehttp package provides a familiar HTTP client interface with
automatic retries and exponential backoff. It is a thin wrapper over the
standard net/http client library and exposes nearly the same public API. This
makes retryablehttp very easy to drop into existing programs.
retryablehttp performs automatic retries under certain conditions. Mainly, if
an error is returned by the client (connection errors, etc.), or if a 500-range
response code is received (except 501), then a retry is invoked after a wait
period. Otherwise, the response is returned and left to the caller to
interpret.
The main difference from net/http is that requests which take a request body
(POST/PUT et. al) can have the body provided in a number of ways (some more or
less efficient) that allow "rewinding" the request body if the initial request
fails so that the full request can be attempted again. See the
godoc for more
details.
Version 0.6.0 and before are compatible with Go prior to 1.12. From 0.6.1 onward, Go 1.12+ is required. From 0.6.7 onward, Go 1.13+ is required.
Using this library should look almost identical to what you would do with
net/http. The most simple example of a GET request is shown below:
resp, err := retryablehttp.Get("/foo")
if err != nil {
panic(err)
}
The returned response object is an *http.Response, the same thing you would
usually get from net/http. Had the request failed one or more times, the above
call would block and retry with exponential backoff.
*http.Client with retriesIt's possible to convert a *retryablehttp.Client directly to a *http.Client.
This makes use of retryablehttp broadly applicable with minimal effort. Simply
configure a *retryablehttp.Client as you wish, and then call StandardClient():
retryClient := retryablehttp.NewClient()
retryClient.RetryMax = 10
standardClient := retryClient.StandardClient() // *http.Client
For more usage and examples see the godoc.
FAQs
Package retryablehttp provides a familiar HTTP client interface with automatic retries and exponential backoff. It is a thin wrapper over the standard net/http client library and exposes nearly the same public API. This makes retryablehttp very easy to drop into existing programs. retryablehttp performs automatic retries under certain conditions. Mainly, if an error is returned by the client (connection errors etc), or if a 500-range response is received, then a retry is invoked. Otherwise, the response is returned and left to the caller to interpret. Requests which take a request body should provide a non-nil function parameter. The best choice is to provide either a function satisfying ReaderFunc which provides multiple io.Readers in an efficient manner, a *bytes.Buffer (the underlying raw byte slice will be used) or a raw byte slice. As it is a reference type, and we will wrap it as needed by readers, we can efficiently re-use the request body without needing to copy it. If an io.Reader (such as a *bytes.Reader) is provided, the full body will be read prior to the first request, and will be efficiently re-used for any retries. ReadSeeker can be used, but some users have observed occasional data races between the net/http library and the Seek functionality of some implementations of ReadSeeker, so should be avoided if possible.
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