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package correlation
import (
"net/http"
)
const (
propagationHeader = "X-Request-ID"
clientNameHeader = "X-GitLab-Client-Name"
)
type instrumentedRoundTripper struct {
delegate http.RoundTripper
config instrumentedRoundTripperConfig
}
// injectRequest will pass the CorrelationId through to a downstream http request
// for propagation.
func (c instrumentedRoundTripper) injectRequest(req *http.Request) {
correlationID := ExtractFromContext(req.Context())
if correlationID != "" {
req.Header.Set(propagationHeader, correlationID)
}
if c.config.clientName != "" {
req.Header.Set(clientNameHeader, c.config.clientName)
}
}
func (c instrumentedRoundTripper) RoundTrip(req *http.Request) (res *http.Response, e error) {
c.injectRequest(req)
return c.delegate.RoundTrip(req)
}
// NewInstrumentedRoundTripper acts as a "client-middleware" for outbound http requests
// adding instrumentation to the outbound request and then delegating to the underlying
// transport.
//
// If will extract the current Correlation-ID from the request context and pass this via
// the X-Request-ID request header to downstream services.
func NewInstrumentedRoundTripper(delegate http.RoundTripper, opts ...InstrumentedRoundTripperOption) http.RoundTripper {
config := applyInstrumentedRoundTripperOptions(opts)
return &instrumentedRoundTripper{delegate: delegate, config: config}
}
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