forked from open-telemetry/opentelemetry-go-contrib
/
consumer.go
134 lines (110 loc) · 3.73 KB
/
consumer.go
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// Copyright The OpenTelemetry Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package main
import (
"context"
"flag"
"fmt"
"log"
"os"
"os/signal"
"strings"
"time"
"github.com/Shopify/sarama"
"go.opentelemetry.io/otel"
semconv "go.opentelemetry.io/otel/semconv/v1.12.0"
"go.opentelemetry.io/otel/trace"
"go.opentelemetry.io/contrib/instrumentation/github.com/Shopify/sarama/otelsarama"
"go.opentelemetry.io/contrib/instrumentation/github.com/Shopify/sarama/otelsarama/example"
)
var (
brokers = flag.String("brokers", os.Getenv("KAFKA_PEERS"), "The Kafka brokers to connect to, as a comma separated list")
)
func main() {
tp, err := example.InitTracer()
if err != nil {
log.Fatal(err)
}
defer func() {
if err := tp.Shutdown(context.Background()); err != nil {
log.Printf("Error shutting down tracer provider: %v", err)
}
}()
flag.Parse()
if *brokers == "" {
flag.PrintDefaults()
os.Exit(1)
}
brokerList := strings.Split(*brokers, ",")
log.Printf("Kafka brokers: %s", strings.Join(brokerList, ", "))
ctx, cancel := signal.NotifyContext(context.Background(), os.Interrupt)
defer cancel()
if err := startConsumerGroup(ctx, brokerList); err != nil {
log.Fatal(err)
}
<-ctx.Done()
}
func startConsumerGroup(ctx context.Context, brokerList []string) error {
consumerGroupHandler := Consumer{}
// Wrap instrumentation
handler := otelsarama.WrapConsumerGroupHandler(&consumerGroupHandler)
config := sarama.NewConfig()
config.Version = sarama.V2_5_0_0
config.Consumer.Offsets.Initial = sarama.OffsetOldest
// Create consumer group
consumerGroup, err := sarama.NewConsumerGroup(brokerList, "example", config)
if err != nil {
return fmt.Errorf("starting consumer group: %w", err)
}
err = consumerGroup.Consume(ctx, []string{example.KafkaTopic}, handler)
if err != nil {
return fmt.Errorf("consuming via handler: %w", err)
}
return nil
}
func printMessage(msg *sarama.ConsumerMessage) {
// Extract tracing info from message
ctx := otel.GetTextMapPropagator().Extract(context.Background(), otelsarama.NewConsumerMessageCarrier(msg))
tr := otel.Tracer("consumer")
_, span := tr.Start(ctx, "consume message", trace.WithAttributes(
semconv.MessagingOperationProcess,
))
defer span.End()
// Emulate Work loads
time.Sleep(1 * time.Second)
log.Println("Successful to read message: ", string(msg.Value))
}
// Consumer represents a Sarama consumer group consumer.
type Consumer struct {
}
// Setup is run at the beginning of a new session, before ConsumeClaim.
func (consumer *Consumer) Setup(sarama.ConsumerGroupSession) error {
return nil
}
// Cleanup is run at the end of a session, once all ConsumeClaim goroutines have exited.
func (consumer *Consumer) Cleanup(sarama.ConsumerGroupSession) error {
return nil
}
// ConsumeClaim must start a consumer loop of ConsumerGroupClaim's Messages().
func (consumer *Consumer) ConsumeClaim(session sarama.ConsumerGroupSession, claim sarama.ConsumerGroupClaim) error {
// NOTE:
// Do not move the code below to a goroutine.
// The `ConsumeClaim` itself is called within a goroutine, see:
// https://github.com/Shopify/sarama/blob/master/consumer_group.go#L27-L29
for message := range claim.Messages() {
printMessage(message)
session.MarkMessage(message, "")
}
return nil
}