Method makeBackendRequest

proxy/proxy.go:1054–1206

(ctx *context, requestContext stdlibcontext.Context)

}

func (p *Proxy) makeBackendRequest(ctx *context, requestContext stdlibcontext.Context) (*http.Response, *proxyError) {
	requestStopWatch, responseStopWatch := newStopWatch(), newStopWatch()
	requestStopWatch.Start()

	defer func() {
		requestStopWatch.Stop()
		responseStopWatch.Stop()
		ctx.proxyRequestElapsed = requestStopWatch.Elapsed()
		ctx.proxyResponseElapsed = responseStopWatch.Elapsed()
	}()

	payloadProtocol := getUpgradeRequest(ctx.Request())

	req, endpointMetrics, err := p.mapRequest(ctx, requestContext)
	if err != nil {
		return nil, &proxyError{err: fmt.Errorf("could not map backend request: %w", err)}
	}

	if res, ok := p.rejectBackend(ctx, req); ok {
		return res, nil
	}

	if endpointMetrics != nil {
		endpointMetrics.IncInflightRequest()
		defer endpointMetrics.DecInflightRequest()
	}

	if p.experimentalUpgrade && payloadProtocol != "" {
		// see also https://github.com/golang/go/blob/9159cd4ec6b0e9475dc9c71c830035c1c4c13483/src/net/http/httputil/reverseproxy.go#L423-L428
		req.Header.Set("Connection", "Upgrade")
		req.Header.Set("Upgrade", payloadProtocol)
		p.makeUpgradeRequest(ctx, req)

		// We are not owner of the connection anymore.
		return nil, &proxyError{handled: true}
	}

	roundTripper, err := p.getRoundTripper(ctx, req)
	if err != nil {
		return nil, &proxyError{err: fmt.Errorf("failed to get roundtripper: %w", err), code: http.StatusBadGateway}
	}

	bag := ctx.StateBag()
	spanName, ok := bag[tracingfilter.OpenTracingProxySpanKey].(string)
	if !ok {
		spanName = "proxy"
	}

	proxySpanOpts := []ot.StartSpanOption{ot.Tags{
		SpanKindTag: SpanKindClient,
	}}
	if parentSpan := ot.SpanFromContext(req.Context()); parentSpan != nil {
		proxySpanOpts = append(proxySpanOpts, ot.ChildOf(parentSpan.Context()))
	}
	ctx.proxySpan = p.tracing.tracer.StartSpan(spanName, proxySpanOpts...)

	u := cloneURL(req.URL)
	u.RawQuery = ""