Add support for traces metadata

browser/module.go

@@ -24,6 +24,7 @@ type (
 		PidRegistry    *pidRegistry
 		remoteRegistry *remoteRegistry
 		initOnce       *sync.Once
+		tracesMetadata map[string]string
 	}
 
 	// JSModule exposes the properties available to the JS script.
@@ -66,9 +67,15 @@ func (m *RootModule) NewModuleInstance(vu k6modules.VU) k6modules.Instance {
 	return &ModuleInstance{
 		mod: &JSModule{
 			Browser: mapBrowserToGoja(moduleVU{
-				VU:                vu,
-				pidRegistry:       m.PidRegistry,
-				browserRegistry:   newBrowserRegistry(context.Background(), vu, m.remoteRegistry, m.PidRegistry),
+				VU:          vu,
+				pidRegistry: m.PidRegistry,
+				browserRegistry: newBrowserRegistry(
+					context.Background(),
+					vu,
+					m.remoteRegistry,
+					m.PidRegistry,
+					m.tracesMetadata,
+				),
 				taskQueueRegistry: newTaskQueueRegistry(vu),
 			}),
 			Devices:         common.GetDevices(),
@@ -94,6 +101,10 @@ func (m *RootModule) initialize(vu k6modules.VU) {
 	if err != nil {
 		k6ext.Abort(vu.Context(), "failed to create remote registry: %v", err)
 	}
+	m.tracesMetadata, err = parseTracesMetadata(initEnv.LookupEnv)
+	if err != nil {
+		k6ext.Abort(vu.Context(), "parsing browser traces metadata: %v", err)
+	}
 	if _, ok := initEnv.LookupEnv(env.EnableProfiling); ok {
 		go startDebugServer()
 	}

browser/registry.go

@@ -173,8 +173,9 @@ func (r *remoteRegistry) isRemoteBrowser() (string, bool) {
 type browserRegistry struct {
 	vu k6modules.VU
 
-	tr     *tracesRegistry
-	trInit sync.Once
+	tr             *tracesRegistry
+	trInit         sync.Once
+	tracesMetadata map[string]string
 
 	mu sync.RWMutex
 	m  map[int64]*common.Browser
@@ -187,7 +188,7 @@ type browserRegistry struct {
 type browserBuildFunc func(ctx context.Context) (*common.Browser, error)
 
 func newBrowserRegistry(
-	ctx context.Context, vu k6modules.VU, remote *remoteRegistry, pids *pidRegistry,
+	ctx context.Context, vu k6modules.VU, remote *remoteRegistry, pids *pidRegistry, tracesMetadata map[string]string,
 ) *browserRegistry {
 	bt := chromium.NewBrowserType(vu)
 	builder := func(ctx context.Context) (*common.Browser, error) {
@@ -215,9 +216,10 @@ func newBrowserRegistry(
 	}
 
 	r := &browserRegistry{
-		vu:      vu,
-		m:       make(map[int64]*common.Browser),
-		buildFn: builder,
+		vu:             vu,
+		tracesMetadata: tracesMetadata,
+		m:              make(map[int64]*common.Browser),
+		buildFn:        builder,
 	}
 
 	exitSubID, exitCh := vu.Events().Global.Subscribe(
@@ -370,7 +372,9 @@ func (r *browserRegistry) initTracesRegistry() {
 	// Use a sync.Once so the traces registry is only initialized once
 	// per VU, as that is the scope for both browser and traces registry.
 	r.trInit.Do(func() {
-		r.tr = newTracesRegistry(browsertrace.NewTracer(r.vu.State().TracerProvider))
+		r.tr = newTracesRegistry(
+			browsertrace.NewTracer(r.vu.State().TracerProvider, r.tracesMetadata),
+		)
 	})
 }
 
@@ -458,6 +462,27 @@ func (r *tracesRegistry) stop() {
 	}
 }
 
+func parseTracesMetadata(envLookup env.LookupFunc) (map[string]string, error) {
+	var (
+		ok bool
+		v  string
+		m  = make(map[string]string)
+	)
+	if v, ok = envLookup(env.TracesMetadata); !ok {
+		return m, nil
+	}
+
+	for _, elem := range strings.Split(v, ",") {
+		kv := strings.Split(elem, "=")
+		if len(kv) != 2 {
+			return nil, fmt.Errorf("%q is not a valid key=value metadata", elem)
+		}
+		m[kv[0]] = kv[1]
+	}
+
+	return m, nil
+}
+
 type taskQueueRegistry struct {
 	vu k6modules.VU
 

browser/registry_test.go

@@ -206,7 +206,7 @@ func TestBrowserRegistry(t *testing.T) {
 		var (
 			ctx             = context.Background()
 			vu              = k6test.NewVU(t)
-			browserRegistry = newBrowserRegistry(ctx, vu, remoteRegistry, &pidRegistry{})
+			browserRegistry = newBrowserRegistry(ctx, vu, remoteRegistry, &pidRegistry{}, nil)
 		)
 
 		vu.ActivateVU()
@@ -248,7 +248,7 @@ func TestBrowserRegistry(t *testing.T) {
 		var (
 			ctx             = context.Background()
 			vu              = k6test.NewVU(t)
-			browserRegistry = newBrowserRegistry(ctx, vu, remoteRegistry, &pidRegistry{})
+			browserRegistry = newBrowserRegistry(ctx, vu, remoteRegistry, &pidRegistry{}, nil)
 		)
 
 		vu.ActivateVU()
@@ -283,7 +283,7 @@ func TestBrowserRegistry(t *testing.T) {
 		var (
 			ctx             = context.Background()
 			vu              = k6test.NewVU(t)
-			browserRegistry = newBrowserRegistry(ctx, vu, remoteRegistry, &pidRegistry{})
+			browserRegistry = newBrowserRegistry(ctx, vu, remoteRegistry, &pidRegistry{}, nil)
 		)
 
 		vu.ActivateVU()
@@ -297,3 +297,86 @@ func TestBrowserRegistry(t *testing.T) {
 		assert.True(t, browserRegistry.stopped.Load())
 	})
 }
+
+func TestParseTracesMetadata(t *testing.T) {
+	testCases := []struct {
+		name        string
+		env         map[string]string
+		expMetadata map[string]string
+		expErrMssg  string
+	}{
+		{
+			name:        "no metadata",
+			env:         make(map[string]string),
+			expMetadata: make(map[string]string),
+		},
+		{
+			name: "one metadata field",
+			env: map[string]string{
+				"K6_BROWSER_TRACES_METADATA": "meta=value",
+			},
+			expMetadata: map[string]string{
+				"meta": "value",
+			},
+		},
+		{
+			name: "one metadata field finishing in comma",
+			env: map[string]string{
+				"K6_BROWSER_TRACES_METADATA": "meta=value,",
+			},
+			expMetadata: map[string]string{
+				"meta": "value",
+			},
+		},
+		{
+			name: "multiple metadata fields",
+			env: map[string]string{
+				"K6_BROWSER_TRACES_METADATA": "meta1=value1,meta2=value2",
+			},
+			expMetadata: map[string]string{
+				"meta1": "value1",
+				"meta2": "value2",
+			},
+		},
+		{
+			name: "multiple metadata fields finishing in comma",
+			env: map[string]string{
+				"K6_BROWSER_TRACES_METADATA": "meta1=value1,meta2=value2,",
+			},
+			expMetadata: map[string]string{
+				"meta1": "value1",
+				"meta2": "value2",
+			},
+		},
+		{
+			name: "invalid metadata",
+			env: map[string]string{
+				"K6_BROWSER_TRACES_METADATA": "thisIsInvalid",
+			},
+			expErrMssg: "is not a valid key=value metadata",
+		},
+		{
+			name: "invalid metadata void",
+			env: map[string]string{
+				"K6_BROWSER_TRACES_METADATA": "",
+			},
+			expErrMssg: "is not a valid key=value metadata",
+		},
+	}
+
+	for _, tc := range testCases {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			lookup := func(key string) (string, bool) {
+				v, ok := tc.env[key]
+				return v, ok
+			}
+			metadata, err := parseTracesMetadata(lookup)
+			if err != nil {
+				assert.ErrorContains(t, err, tc.expErrMssg)
+				return
+			}
+			assert.Equal(t, tc.expMetadata, metadata)
+		})
+	}
+}

env/env.go

@@ -65,6 +65,14 @@ const (
 	LogCategoryFilter = "K6_BROWSER_LOG_CATEGORY_FILTER"
 )
 
+// Tracing.
+const (
+	// TracesMetadata is an environment variable that can be used to
+	// set additional metadata to be included in the generated traces.
+	// The format must comply with: key1=value1,key2=value2,...
+	TracesMetadata = "K6_BROWSER_TRACES_METADATA"
+)
+
 // LookupFunc defines a function to look up a key from the environment.
 type LookupFunc func(key string) (string, bool)
 

trace/trace.go

@@ -33,14 +33,17 @@ type liveSpan struct {
 type Tracer struct {
 	trace.Tracer
 
+	metadata []attribute.KeyValue
+
 	liveSpansMu sync.RWMutex
 	liveSpans   map[string]*liveSpan
 }
 
 // NewTracer creates a new Tracer from the given TracerProvider.
-func NewTracer(tp k6lib.TracerProvider, options ...trace.TracerOption) *Tracer {
+func NewTracer(tp k6lib.TracerProvider, metadata map[string]string, options ...trace.TracerOption) *Tracer {
 	return &Tracer{
 		Tracer:    tp.Tracer(tracerName, options...),
+		metadata:  buildMetadataAttributes(metadata),
 		liveSpans: make(map[string]*liveSpan),
 	}
 }
@@ -56,6 +59,8 @@ func (t *Tracer) TraceAPICall(
 	t.liveSpansMu.Lock()
 	defer t.liveSpansMu.Unlock()
 
+	opts = append(opts, trace.WithAttributes(t.metadata...))
+
 	ls := t.liveSpans[targetID]
 	if ls == nil {
 		return t.Start(ctx, spanName, opts...)
@@ -89,6 +94,8 @@ func (t *Tracer) TraceNavigation(
 		ls = &liveSpan{}
 	}
 
+	opts = append(opts, trace.WithAttributes(t.metadata...))
+
 	ls.ctx, ls.span = t.Start(ctx, url, opts...)
 	t.liveSpans[targetID] = ls
 
@@ -127,9 +134,20 @@ func (t *Tracer) TraceEvent(
 		return ctx, NoopSpan{}
 	}
 
+	opts = append(opts, trace.WithAttributes(t.metadata...))
+
 	return t.Start(ls.ctx, eventName, opts...)
 }
 
+func buildMetadataAttributes(metadata map[string]string) []attribute.KeyValue {
+	meta := make([]attribute.KeyValue, 0, len(metadata))
+	for mk, mv := range metadata {
+		meta = append(meta, attribute.String(mk, mv))
+	}
+
+	return meta
+}
+
 // NoopSpan represents a noop span.
 type NoopSpan struct {
 	trace.Span