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Retry middleware : store headers per attempts and propagate them when responding.

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This commit is contained in:
Julien Levesy 2019-01-07 23:18:03 +01:00 • committed by Traefiker Bot
parent d7bd69714d
commit fc8c24e987
4 changed files with 118 additions and 13 deletions
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21
old/middlewares/retry.go
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@ -44,9 +44,7 @@ func (retry *Retry) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
attempts := 1
for {
attemptsExhausted := attempts >= retry.attempts
shouldRetry := !attemptsExhausted
shouldRetry := attempts < retry.attempts
retryResponseWriter := newRetryResponseWriter(rw, shouldRetry)
// Disable retries when the backend already received request data
@ -99,6 +97,7 @@ type retryResponseWriter interface {
func newRetryResponseWriter(rw http.ResponseWriter, shouldRetry bool) retryResponseWriter {
responseWriter := &retryResponseWriterWithoutCloseNotify{
responseWriter: rw,
headers: make(http.Header),
shouldRetry: shouldRetry,
}
if _, ok := rw.(http.CloseNotifier); ok {
@ -109,6 +108,7 @@ func newRetryResponseWriter(rw http.ResponseWriter, shouldRetry bool) retryRespo
type retryResponseWriterWithoutCloseNotify struct {
responseWriter http.ResponseWriter
headers http.Header
shouldRetry bool
}
@ -121,10 +121,7 @@ func (rr *retryResponseWriterWithoutCloseNotify) DisableRetries() {
}
func (rr *retryResponseWriterWithoutCloseNotify) Header() http.Header {
if rr.ShouldRetry() {
return make(http.Header)
}
return rr.responseWriter.Header()
return rr.headers
}
func (rr *retryResponseWriterWithoutCloseNotify) Write(buf []byte) (int, error) {
@ -147,6 +144,16 @@ func (rr *retryResponseWriterWithoutCloseNotify) WriteHeader(code int) {
if rr.ShouldRetry() {
return
}
// In that case retry case is set to false which means we at least managed
// to write headers to the backend : we are not going to perform any further retry.
// So it is now safe to alter current response headers with headers collected during
// the latest try before writing headers to client.
headers := rr.responseWriter.Header()
for header, value := range rr.headers {
headers[header] = value
}
rr.responseWriter.WriteHeader(code)
}