// Round trips the request to one of the endpoints and returns the response.
func (l *HttpLocation) RoundTrip(req request.Request) (*http.Response, error) {
// Get options and transport as one single read transaction.
// Options and transport may change if someone calls SetOptions
o, tr := l.GetOptionsAndTransport()
originalRequest := req.GetHttpRequest()
// Check request size first, if that exceeds the limit, we don't bother reading the request.
if l.isRequestOverLimit(req) {
return nil, errors.FromStatus(http.StatusRequestEntityTooLarge)
}
// Read the body while keeping this location's limits in mind. This reader controls the maximum bytes
// to read into memory and disk. This reader returns an error if the total request size exceeds the
// prefefined MaxSizeBytes. This can occur if we got chunked request, in this case ContentLength would be set to -1
// and the reader would be unbounded bufio in the http.Server
body, err := netutils.NewBodyBufferWithOptions(originalRequest.Body, netutils.BodyBufferOptions{
MemBufferBytes: o.Limits.MaxMemBodyBytes,
MaxSizeBytes: o.Limits.MaxBodyBytes,
})
if err != nil {
return nil, err
}
if body == nil {
return nil, fmt.Errorf("Empty body")
}
// Set request body to buffered reader that can replay the read and execute Seek
req.SetBody(body)
// Note that we don't change the original request Body as it's handled by the http server
defer body.Close()
for {
_, err := req.GetBody().Seek(0, 0)
if err != nil {
return nil, err
}
endpoint, err := l.loadBalancer.NextEndpoint(req)
if err != nil {
log.Errorf("Load Balancer failure: %s", err)
return nil, err
}
// Adds headers, changes urls. Note that we rewrite request each time we proxy it to the
// endpoint, so that each try gets a fresh start
req.SetHttpRequest(l.copyRequest(originalRequest, req.GetBody(), endpoint))
// In case if error is not nil, we allow load balancer to choose the next endpoint
// e.g. to do request failover. Nil error means that we got proxied the request successfully.
response, err := l.proxyToEndpoint(tr, &o, endpoint, req)
if o.FailoverPredicate(req) {
continue
} else {
return response, err
}
}
log.Errorf("All endpoints failed!")
return nil, fmt.Errorf("All endpoints failed")
}
// readResponse reads the response body into buffer, closes the original response body to release the connection
// and replaces the body with the buffer.
func readResponse(l *Limits, re *http.Response, err error) (*http.Response, error) {
if re == nil || re.Body == nil {
return nil, err
}
// Closing a response body releases connection to the pool in transport
body := re.Body
defer body.Close()
newBody, err := netutils.NewBodyBufferWithOptions(body, netutils.BodyBufferOptions{
MemBufferBytes: l.MaxMemBodyBytes,
MaxSizeBytes: l.MaxBodyBytes,
})
if err != nil {
return nil, err
}
re.Body = newBody
return re, nil
}