import (
"context"
"fmt"
"io"
"sync/atomic"
"time"
"cloud.google.com/go/pubsub"
texporter "github.com/GoogleCloudPlatform/opentelemetry-operations-go/exporter/trace"
"go.opentelemetry.io/otel"
"go.opentelemetry.io/otel/sdk/resource"
sdktrace "go.opentelemetry.io/otel/sdk/trace"
semconv "go.opentelemetry.io/otel/semconv/v1.24.0"
"google.golang.org/api/option"
)
func subscribeOpenTelemetryTracing(w io.Writer, projectID, subID string, sampleRate float64) error {
// projectID := "my-project-id"
// subID := "my-sub"
// sampleRate := "1.0"
ctx := context.Background()
exporter, err := texporter.New(texporter.WithProjectID(projectID),
// Disable spans created by the exporter.
texporter.WithTraceClientOptions(
[]option.ClientOption{option.WithTelemetryDisabled()},
),
)
if err != nil {
return fmt.Errorf("error instantiating exporter: %w", err)
}
resources := resource.NewWithAttributes(
semconv.SchemaURL,
semconv.ServiceNameKey.String("subscriber"),
)
// Instantiate a tracer provider with the following settings
tp := sdktrace.NewTracerProvider(
sdktrace.WithBatcher(exporter),
sdktrace.WithResource(resources),
sdktrace.WithSampler(
sdktrace.ParentBased(sdktrace.TraceIDRatioBased(sampleRate)),
),
)
defer tp.ForceFlush(ctx) // flushes any pending spans
otel.SetTracerProvider(tp)
// Create a new client with tracing enabled.
client, err := pubsub.NewClientWithConfig(ctx, projectID, &pubsub.ClientConfig{
EnableOpenTelemetryTracing: true,
})
if err != nil {
return fmt.Errorf("pubsub.NewClient: %w", err)
}
defer client.Close()
sub := client.Subscription(subID)
// Receive messages for 10 seconds, which simplifies testing.
// Comment this out in production, since `Receive` should
// be used as a long running operation.
ctx, cancel := context.WithTimeout(ctx, 10*time.Second)
defer cancel()
var received int32
err = sub.Receive(ctx, func(_ context.Context, msg *pubsub.Message) {
fmt.Fprintf(w, "Got message: %q\n", string(msg.Data))
atomic.AddInt32(&received, 1)
msg.Ack()
})
if err != nil {
return fmt.Errorf("sub.Receive: %w", err)
}
fmt.Fprintf(w, "Received %d messages\n", received)
return nil
}
