Product Catalog Service
This service is responsible to return information about products. The service can be used to get all products, search for specific products, or return details about any single product.
Product Catalog service source
Traces
Initializing Tracing
The OpenTelemetry SDK is initialized from main using the initTracerProvider
function.
func initTracerProvider() *sdktrace.TracerProvider {
ctx := context.Background()
exporter, err := otlptracegrpc.New(ctx)
if err != nil {
log.Fatalf("OTLP Trace gRPC Creation: %v", err)
}
tp := sdktrace.NewTracerProvider(
sdktrace.WithBatcher(exporter),
sdktrace.WithResource(initResource()),
)
otel.SetTracerProvider(tp)
otel.SetTextMapPropagator(propagation.NewCompositeTextMapPropagator(propagation.TraceContext{}, propagation.Baggage{}))
return tp
}
You should call TracerProvider.Shutdown() when your service is shutdown to
ensure all spans are exported. This service makes that call as part of a
deferred function in main
tp := InitTracerProvider()
defer func() {
if err := tp.Shutdown(context.Background()); err != nil {
log.Fatalf("Tracer Provider Shutdown: %v", err)
}
}()
Adding gRPC auto-instrumentation
This service receives gRPC requests, which are instrumented in the main function as part of the gRPC server creation.
srv := grpc.NewServer(
grpc.StatsHandler(otelgrpc.NewServerHandler()),
)
This service will issue outgoing gRPC calls, which are all instrumented by wrapping the gRPC client with instrumentation.
func createClient(ctx context.Context, svcAddr string) (*grpc.ClientConn, error) {
return grpc.DialContext(ctx, svcAddr,
grpc.WithTransportCredentials(insecure.NewCredentials()),
grpc.WithStatsHandler(otelgrpc.NewClientHandler()),
)
}
Add attributes to auto-instrumented spans
Within the execution of auto-instrumented code you can get current span from context.
span := trace.SpanFromContext(ctx)
Adding attributes to a span is accomplished using SetAttributes on the span
object. In the GetProduct function an attribute for the product ID is added to
the span.
span.SetAttributes(
attribute.String("app.product.id", req.Id),
)
Setting span status
This service can catch and handle an error condition based on a feature flag. In
an error condition, the span status is set accordingly using SetStatus on the
span object. You can see this in the GetProduct function.
msg := fmt.Sprintf("Error: ProductCatalogService Fail Feature Flag Enabled")
span.SetStatus(otelcodes.Error, msg)
Add span events
Adding span events is accomplished using AddEvent on the span object. In the
GetProduct function a span event is added when an error condition is handled,
or when a product is successfully found.
span.AddEvent(msg)
Metrics
Initializing Metrics
The OpenTelemetry SDK is initialized from main using the initMeterProvider
function.
func initMeterProvider() *sdkmetric.MeterProvider {
ctx := context.Background()
exporter, err := otlpmetricgrpc.New(ctx)
if err != nil {
log.Fatalf("new otlp metric grpc exporter failed: %v", err)
}
mp := sdkmetric.NewMeterProvider(sdkmetric.WithReader(sdkmetric.NewPeriodicReader(exporter)))
global.SetMeterProvider(mp)
return mp
}
You should call initMeterProvider.Shutdown() when your service is shutdown to
ensure all records are exported. This service makes that call as part of a
deferred function in main.
mp := initMeterProvider()
defer func() {
if err := mp.Shutdown(context.Background()); err != nil {
log.Fatalf("Error shutting down meter provider: %v", err)
}
}()
Adding golang runtime auto-instrumentation
Golang runtime is instrumented in the main function
err := runtime.Start(runtime.WithMinimumReadMemStatsInterval(time.Second))
if err != nil {
log.Fatal(err)
}
Logs
TBD