ddtrace/tracer: add SetUser function and userTagOption

ddtrace/tracer/option.go

@@ -829,3 +829,41 @@ func StackFrames(n, skip uint) FinishOption {
 		cfg.SkipStackFrames = skip
 	}
 }
+
+// UserMonitoringOption represents a function that can be provided as a parameter to SetUser.
+type UserMonitoringOption func(Span)
+
+// WithUserEmail returns the option setting the email of the authenticated user.
+func WithUserEmail(email string) UserMonitoringOption {
+	return func(s Span) {
+		s.SetTag("usr.email", email)
+	}
+}
+
+// WithUserName returns the option setting the name of the authenticated user.
+func WithUserName(name string) UserMonitoringOption {
+	return func(s Span) {
+		s.SetTag("usr.name", name)
+	}
+}
+
+// WithUserSessionID returns the option setting the session ID of the authenticated user.
+func WithUserSessionID(sessionID string) UserMonitoringOption {
+	return func(s Span) {
+		s.SetTag("usr.session_id", sessionID)
+	}
+}
+
+// WithUserRole returns the option setting the role of the authenticated user.
+func WithUserRole(role string) UserMonitoringOption {
+	return func(s Span) {
+		s.SetTag("usr.role", role)
+	}
+}
+
+// WithUserScope returns the option setting the scope (authorizations) of the authenticated user
+func WithUserScope(scope string) UserMonitoringOption {
+	return func(s Span) {
+		s.SetTag("usr.scope", scope)
+	}
+}

ddtrace/tracer/tracer.go

@@ -153,6 +153,23 @@ func Inject(ctx ddtrace.SpanContext, carrier interface{}) error {
 	return internal.GetGlobalTracer().Inject(ctx, carrier)
 }
 
+// SetUser associates user information to the current trace which the
+// provided span belongs to. The options can be used to tune which user
+// bit of information gets monitored.
+func SetUser(s Span, id string, opts ...UserMonitoringOption) {
+	if s == nil {
+		return
+	}
+	if span, ok := s.(*span); ok && span.context != nil {
+		span = span.context.trace.root
+		s = span
+	}
+	s.SetTag("usr.id", id)
+	for _, fn := range opts {
+		fn(s)
+	}
+}
+
 // payloadQueueSize is the buffer size of the trace channel.
 const payloadQueueSize = 1000
 

ddtrace/tracer/tracer_test.go

@@ -1694,6 +1694,47 @@ func TestTakeStackTrace(t *testing.T) {
 	})
 }
 
+func TestUserMonitoring(t *testing.T) {
+	const id = "john.doe#12345"
+	const name = "John Doe"
+	const email = "john.doe@hostname.com"
+	const scope = "read:message, write:files"
+	const role = "admin"
+	const sessionID = "session#12345"
+	expected := []struct{ key, value string }{
+		{key: "usr.id", value: id},
+		{key: "usr.name", value: name},
+		{key: "usr.email", value: email},
+		{key: "usr.scope", value: scope},
+		{key: "usr.role", value: role},
+		{key: "usr.session_id", value: sessionID},
+	}
+	tr := newTracer()
+	defer tr.Stop()
+
+	t.Run("root", func(t *testing.T) {
+		s := tr.newRootSpan("root", "test", "test")
+		SetUser(s, id, WithUserEmail(email), WithUserName(name), WithUserScope(scope),
+			WithUserRole(role), WithUserSessionID(sessionID))
+		s.Finish()
+		for _, pair := range expected {
+			assert.Equal(t, pair.value, s.Meta[pair.key])
+		}
+	})
+
+	t.Run("nested", func(t *testing.T) {
+		root := tr.newRootSpan("root", "test", "test")
+		child := tr.newChildSpan("child", root)
+		SetUser(child, id, WithUserEmail(email), WithUserName(name), WithUserScope(scope),
+			WithUserRole(role), WithUserSessionID(sessionID))
+		child.Finish()
+		root.Finish()
+		for _, pair := range expected {
+			assert.Equal(t, pair.value, root.Meta[pair.key])
+		}
+	})
+}
+
 // BenchmarkTracerStackFrames tests the performance of taking stack trace.
 func BenchmarkTracerStackFrames(b *testing.B) {
 	tracer, _, _, stop := startTestTracer(b, WithSampler(NewRateSampler(0)))