client: pass delegated exporter as parameter

Avoid client package having dependency on global detect package.

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

client/client.go

@@ -5,7 +5,6 @@ import (
 	"crypto/tls"
 	"crypto/x509"
 	"io/ioutil"
-	"log"
 	"net"
 	"net/url"
 	"strings"
@@ -18,7 +17,6 @@ import (
 	"github.com/moby/buildkit/session/grpchijack"
 	"github.com/moby/buildkit/util/appdefaults"
 	"github.com/moby/buildkit/util/grpcerrors"
-	"github.com/moby/buildkit/util/tracing/detect"
 	"github.com/moby/buildkit/util/tracing/otlptracegrpc"
 	"github.com/pkg/errors"
 	"go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc"
@@ -50,6 +48,7 @@ func New(ctx context.Context, address string, opts ...ClientOpt) (*Client, error
 
 	var customTracer bool // allows manually setting disabling tracing even if tracer in context
 	var tracerProvider trace.TracerProvider
+	var tracerDelegate TracerDelegate
 
 	for _, o := range opts {
 		if _, ok := o.(*withFailFast); ok {
@@ -71,6 +70,9 @@ func New(ctx context.Context, address string, opts ...ClientOpt) (*Client, error
 			gopts = append(gopts, grpc.WithContextDialer(wd.dialer))
 			needDialer = false
 		}
+		if wt, ok := o.(*withTracerDelegate); ok {
+			tracerDelegate = wt
+		}
 	}
 
 	if !customTracer {
@@ -132,31 +134,20 @@ func New(ctx context.Context, address string, opts ...ClientOpt) (*Client, error
 		conn: conn,
 	}
 
-	_ = c.setupDelegatedTracing(ctx) // ignore error
+	if tracerDelegate != nil {
+		_ = c.setupDelegatedTracing(ctx, tracerDelegate) // ignore error
+	}
 
 	return c, nil
 }
 
-func (c *Client) setupDelegatedTracing(ctx context.Context) error {
-	exp, err := detect.Exporter()
-	if err != nil {
-		return err
-	}
-
-	log.Printf("exporter %v %T", exp, exp)
-	del, ok := exp.(interface {
-		SetDelegate(context.Context, sdktrace.SpanExporter) error
-	})
-	if !ok {
-		return nil
-	}
-
+func (c *Client) setupDelegatedTracing(ctx context.Context, td TracerDelegate) error {
 	pd := otlptracegrpc.NewClient(c.conn)
 	e, err := otlptrace.New(ctx, pd)
 	if err != nil {
 		return nil
 	}
-	return del.SetDelegate(ctx, e)
+	return td.SetSpanExporter(ctx, e)
 }
 
 func (c *Client) controlClient() controlapi.ControlClient {
@@ -239,6 +230,20 @@ type withTracer struct {
 	tp trace.TracerProvider
 }
 
+type TracerDelegate interface {
+	SetSpanExporter(context.Context, sdktrace.SpanExporter) error
+}
+
+func WithTracerDelegate(td TracerDelegate) ClientOpt {
+	return &withTracerDelegate{
+		TracerDelegate: td,
+	}
+}
+
+type withTracerDelegate struct {
+	TracerDelegate
+}
+
 func resolveDialer(address string) (func(context.Context, string) (net.Conn, error), error) {
 	ch, err := connhelper.GetConnectionHelper(address)
 	if err != nil {

cmd/buildctl/common/common.go

@@ -8,6 +8,7 @@ import (
 	"time"
 
 	"github.com/moby/buildkit/client"
+	"github.com/moby/buildkit/util/tracing/detect"
 	"github.com/pkg/errors"
 	"github.com/urfave/cli"
 	"go.opentelemetry.io/otel/trace"
@@ -66,6 +67,15 @@ func ResolveClient(c *cli.Context) (*client.Client, error) {
 
 	if span := trace.SpanFromContext(ctx); span.SpanContext().IsValid() {
 		opts = append(opts, client.WithTracerProvider(span.TracerProvider()))
+
+		exp, err := detect.Exporter()
+		if err != nil {
+			return nil, err
+		}
+
+		if td, ok := exp.(client.TracerDelegate); ok {
+			opts = append(opts, client.WithTracerDelegate(td))
+		}
 	}
 
 	if caCert != "" || cert != "" || key != "" {

util/tracing/detect/delegated/delegated.go

@@ -8,7 +8,7 @@ import (
 	sdktrace "go.opentelemetry.io/otel/sdk/trace"
 )
 
-const maxBuffer = 128
+const maxBuffer = 256
 
 var exp = &Exporter{}
 
@@ -19,9 +19,9 @@ func init() {
 }
 
 type Exporter struct {
-	mu       sync.Mutex
-	delegate sdktrace.SpanExporter
-	buffer   []sdktrace.ReadOnlySpan
+	mu        sync.Mutex
+	exporters []sdktrace.SpanExporter
+	buffer    []sdktrace.ReadOnlySpan
 }
 
 var _ sdktrace.SpanExporter = &Exporter{}
@@ -30,8 +30,14 @@ func (e *Exporter) ExportSpans(ctx context.Context, ss []sdktrace.ReadOnlySpan)
 	e.mu.Lock()
 	defer e.mu.Unlock()
 
-	if e.delegate != nil {
-		return e.delegate.ExportSpans(ctx, ss)
+	var err error
+	for _, e := range e.exporters {
+		if err1 := e.ExportSpans(ctx, ss); err1 != nil {
+			err = err1
+		}
+	}
+	if err != nil {
+		return err
 	}
 
 	if len(e.buffer) > maxBuffer {
@@ -46,23 +52,24 @@ func (e *Exporter) Shutdown(ctx context.Context) error {
 	e.mu.Lock()
 	defer e.mu.Unlock()
 
-	if e.delegate != nil {
-		return e.delegate.Shutdown(ctx)
+	var err error
+	for _, e := range e.exporters {
+		if err1 := e.Shutdown(ctx); err1 != nil {
+			err = err1
+		}
 	}
 
-	return nil
+	return err
 }
 
-func (e *Exporter) SetDelegate(ctx context.Context, del sdktrace.SpanExporter) error {
+func (e *Exporter) SetSpanExporter(ctx context.Context, exp sdktrace.SpanExporter) error {
 	e.mu.Lock()
 	defer e.mu.Unlock()
 
-	e.delegate = del
+	e.exporters = append(e.exporters, exp)
 
 	if len(e.buffer) > 0 {
-		err := e.delegate.ExportSpans(ctx, e.buffer)
-		e.buffer = nil
-		return err
+		return exp.ExportSpans(ctx, e.buffer)
 	}
 	return nil
 }