vendor: update buildkit to opentelemetry support

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

vendor/github.com/moby/buildkit/util/tracing/tracing.go

@@ -0,0 +1,133 @@
+package tracing
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/codes"
+	"go.opentelemetry.io/otel/propagation"
+	semconv "go.opentelemetry.io/otel/semconv/v1.4.0"
+	"go.opentelemetry.io/otel/trace"
+)
+
+// StartSpan starts a new span as a child of the span in context.
+// If there is no span in context then this is a no-op.
+func StartSpan(ctx context.Context, operationName string, opts ...trace.SpanStartOption) (trace.Span, context.Context) {
+	parent := trace.SpanFromContext(ctx)
+	tracer := trace.NewNoopTracerProvider().Tracer("")
+	if parent != nil && parent.SpanContext().IsValid() {
+		tracer = parent.TracerProvider().Tracer("")
+	}
+	ctx, span := tracer.Start(ctx, operationName, opts...)
+	return span, ctx
+}
+
+// FinishWithError finalizes the span and sets the error if one is passed
+func FinishWithError(span trace.Span, err error) {
+	if err != nil {
+		span.RecordError(err)
+		if _, ok := err.(interface {
+			Cause() error
+		}); ok {
+			span.SetAttributes(attribute.String(string(semconv.ExceptionStacktraceKey), fmt.Sprintf("%+v", err)))
+		}
+		span.SetStatus(codes.Error, err.Error())
+	}
+	span.End()
+}
+
+// ContextWithSpanFromContext sets the tracing span of a context from other
+// context if one is not already set. Alternative would be
+// context.WithoutCancel() that would copy the context but reset ctx.Done
+func ContextWithSpanFromContext(ctx, ctx2 context.Context) context.Context {
+	// if already is a span then noop
+	if span := trace.SpanFromContext(ctx); span.SpanContext().IsValid() {
+		return ctx
+	}
+	if span := trace.SpanFromContext(ctx2); span != nil && span.SpanContext().IsValid() {
+		return trace.ContextWithSpan(ctx, span)
+	}
+	return ctx
+}
+
+var DefaultTransport http.RoundTripper = &Transport{
+	RoundTripper: NewTransport(http.DefaultTransport),
+}
+
+var DefaultClient = &http.Client{
+	Transport: DefaultTransport,
+}
+
+var propagators = propagation.NewCompositeTextMapPropagator(propagation.TraceContext{}, propagation.Baggage{})
+
+type Transport struct {
+	http.RoundTripper
+}
+
+func NewTransport(rt http.RoundTripper) http.RoundTripper {
+	// TODO: switch to otelhttp. needs upstream updates to avoid transport-global tracer
+	return &Transport{
+		RoundTripper: rt,
+	}
+}
+
+func (t *Transport) RoundTrip(req *http.Request) (*http.Response, error) {
+	span := trace.SpanFromContext(req.Context())
+	if !span.SpanContext().IsValid() { // no tracer connected with either request or transport
+		return t.RoundTripper.RoundTrip(req)
+	}
+
+	ctx, span := span.TracerProvider().Tracer("").Start(req.Context(), req.Method)
+
+	req = req.WithContext(ctx)
+	span.SetAttributes(semconv.HTTPClientAttributesFromHTTPRequest(req)...)
+	propagators.Inject(ctx, propagation.HeaderCarrier(req.Header))
+
+	resp, err := t.RoundTripper.RoundTrip(req)
+	if err != nil {
+		span.RecordError(err)
+		span.End()
+		return resp, err
+	}
+
+	span.SetAttributes(semconv.HTTPAttributesFromHTTPStatusCode(resp.StatusCode)...)
+	span.SetStatus(semconv.SpanStatusFromHTTPStatusCode(resp.StatusCode))
+
+	if req.Method == "HEAD" {
+		span.End()
+	} else {
+		resp.Body = &wrappedBody{ctx: ctx, span: span, body: resp.Body}
+	}
+
+	return resp, err
+}
+
+type wrappedBody struct {
+	ctx  context.Context
+	span trace.Span
+	body io.ReadCloser
+}
+
+var _ io.ReadCloser = &wrappedBody{}
+
+func (wb *wrappedBody) Read(b []byte) (int, error) {
+	n, err := wb.body.Read(b)
+
+	switch err {
+	case nil:
+		// nothing to do here but fall through to the return
+	case io.EOF:
+		wb.span.End()
+	default:
+		wb.span.RecordError(err)
+	}
+	return n, err
+}
+
+func (wb *wrappedBody) Close() error {
+	wb.span.End()
+	return wb.body.Close()
+}