feat: extend configuration to support custom randomNumber func

config/config.go

@@ -277,6 +277,10 @@ func (c Configuration) NewTracer(options ...Option) (opentracing.Tracer, io.Clos
 		tracerOptions = append(tracerOptions, jaeger.TracerOptions.Gen128Bit(true))
 	}
 
+	if opts.randomNumber != nil {
+		tracerOptions = append(tracerOptions, jaeger.TracerOptions.RandomNumber(opts.randomNumber))
+	}
+
 	for _, tag := range opts.tags {
 		tracerOptions = append(tracerOptions, jaeger.TracerOptions.Tag(tag.Key, tag.Value))
 	}

config/config_test.go

@@ -899,3 +899,19 @@ func TestThrottlerDefaultConfig(t *testing.T) {
 	assert.NoError(t, err)
 	defer closeCloser(t, closer)
 }
+
+func TestWithRandomNumber(t *testing.T) {
+	const traceID uint64 = 1
+
+	cfg := &Configuration{
+		ServiceName: "test-random-number",
+	}
+	randomNum := func() uint64 { return traceID }
+	tracer, closer, err := cfg.NewTracer(WithRandomNumber(randomNum))
+	span := tracer.StartSpan("test-span")
+	spanCtx := span.Context().(jaeger.SpanContext)
+
+	assert.NoError(t, err)
+	assert.Equal(t, traceID, spanCtx.TraceID().Low)
+	defer closeCloser(t, closer)
+}

config/options.go

@@ -40,6 +40,7 @@ type Options struct {
 	tags                        []opentracing.Tag
 	injectors                   map[interface{}]jaeger.Injector
 	extractors                  map[interface{}]jaeger.Extractor
+	randomNumber                func() uint64
 }
 
 // Metrics creates an Option that initializes Metrics in the tracer,
@@ -147,6 +148,13 @@ func Extractor(format interface{}, extractor jaeger.Extractor) Option {
 	}
 }
 
+// WithRandomNumber supplies a random number generator function to the Tracer used to generate trace and span IDs.
+func WithRandomNumber(f func() uint64) Option {
+	return func(c *Options) {
+		c.randomNumber = f
+	}
+}
+
 func applyOptions(options ...Option) Options {
 	opts := Options{
 		injectors:  make(map[interface{}]jaeger.Injector),