snapshot of https://github.com/ThreeDotsLabs/watermill.git (master, 2026-09-15; blobs > 131072B omitted)

_examples/real-world-examples/consumer-groups/newsletter-service/main.go

@@ -0,0 +1,395 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/ThreeDotsLabs/watermill"
+	"github.com/ThreeDotsLabs/watermill-redisstream/pkg/redisstream"
+	"github.com/ThreeDotsLabs/watermill-routing-example/server/common"
+	"github.com/ThreeDotsLabs/watermill/components/cqrs"
+	"github.com/ThreeDotsLabs/watermill/message"
+	"github.com/ThreeDotsLabs/watermill/message/router/middleware"
+	"github.com/redis/go-redis/v9"
+)
+
+var (
+	replica                = os.Getenv("REPLICA")
+	serviceName            = "newsletter-service"
+	serviceNameWithReplica = serviceName + "-" + replica
+)
+
+func main() {
+	logger := watermill.NewStdLogger(false, false)
+
+	router, err := message.NewRouter(message.RouterConfig{}, logger)
+	if err != nil {
+		panic(err)
+	}
+
+	pubClient := redis.NewClient(&redis.Options{
+		Addr: "redis:6379",
+	})
+	publisher, err := redisstream.NewPublisher(
+		redisstream.PublisherConfig{
+			Client: pubClient,
+		},
+		logger,
+	)
+	if err != nil {
+		panic(err)
+	}
+
+	router.AddMiddleware(middleware.Recoverer)
+	router.AddMiddleware(common.NotifyMiddleware(publisher, serviceNameWithReplica))
+
+	subClient := redis.NewClient(&redis.Options{
+		Addr: "redis:6379",
+	})
+	subscriber, err := redisstream.NewSubscriber(
+		redisstream.SubscriberConfig{
+			Client:        subClient,
+			ConsumerGroup: "",
+		},
+		logger,
+	)
+	if err != nil {
+		panic(err)
+	}
+
+	newsletterServiceGroupSubscriber, err := redisstream.NewSubscriber(
+		redisstream.SubscriberConfig{
+			Client:        subClient,
+			ConsumerGroup: "newsletter-service",
+		},
+		logger,
+	)
+	if err != nil {
+		panic(err)
+	}
+
+	addToPromotionsListGroupSubscriber, err := redisstream.NewSubscriber(
+		redisstream.SubscriberConfig{
+			Client:        subClient,
+			ConsumerGroup: "AddToPromotionsList",
+		},
+		logger,
+	)
+	if err != nil {
+		panic(err)
+	}
+
+	addToNewsListGroupSubscriber, err := redisstream.NewSubscriber(
+		redisstream.SubscriberConfig{
+			Client:        subClient,
+			ConsumerGroup: "AddToNewsList",
+		},
+		logger,
+	)
+	if err != nil {
+		panic(err)
+	}
+
+	if replica == "1" {
+		router.AddConsumerHandler(
+			"OnUserSignedUp-1",
+			"UserSignedUp-1",
+			subscriber,
+			func(msg *message.Message) error {
+				var event common.UserSignedUp
+				err := json.Unmarshal(msg.Payload, &event)
+				if err != nil {
+					return err
+				}
+
+				if !event.Consents.Marketing {
+					return nil
+				}
+
+				fmt.Println("Adding user", event.UserID, "to the promotions list")
+
+				return nil
+			},
+		)
+
+		router.AddConsumerHandler(
+			"OnUserSignedUp-2",
+			"UserSignedUp-2",
+			subscriber,
+			func(msg *message.Message) error {
+				var event common.UserSignedUp
+				err := json.Unmarshal(msg.Payload, &event)
+				if err != nil {
+					return err
+				}
+
+				if !event.Consents.Marketing {
+					return nil
+				}
+
+				fmt.Println("Adding user", event.UserID, "to the promotions list")
+
+				return nil
+			},
+		)
+
+		router.AddConsumerHandler(
+			"AddToPromotionsList-5",
+			"UserSignedUp-5",
+			newsletterServiceGroupSubscriber,
+			func(msg *message.Message) error {
+				var event common.UserSignedUp
+				err := json.Unmarshal(msg.Payload, &event)
+				if err != nil {
+					return err
+				}
+
+				if !event.Consents.Marketing {
+					return nil
+				}
+
+				fmt.Println("Adding user", event.UserID, "to the promotions list")
+
+				return nil
+			},
+		)
+
+		router.AddConsumerHandler(
+			"AddToNewsList-5",
+			"UserSignedUp-5",
+			newsletterServiceGroupSubscriber,
+			func(msg *message.Message) error {
+				var event common.UserSignedUp
+				err := json.Unmarshal(msg.Payload, &event)
+				if err != nil {
+					return err
+				}
+
+				if !event.Consents.News {
+					return nil
+				}
+
+				fmt.Println("Adding user", event.UserID, "to the news list")
+
+				return nil
+			},
+		)
+
+		router.AddConsumerHandler(
+			"AddToPromotionsList-6",
+			"UserSignedUp-6",
+			addToPromotionsListGroupSubscriber,
+			func(msg *message.Message) error {
+				var event common.UserSignedUp
+				err := json.Unmarshal(msg.Payload, &event)
+				if err != nil {
+					return err
+				}
+
+				if !event.Consents.Marketing {
+					return nil
+				}
+
+				fmt.Println("Adding user", event.UserID, "to the promotions list")
+
+				return nil
+			},
+		)
+
+		router.AddConsumerHandler(
+			"AddToNewsList-6",
+			"UserSignedUp-6",
+			addToNewsListGroupSubscriber,
+			func(msg *message.Message) error {
+				var event common.UserSignedUp
+				err := json.Unmarshal(msg.Payload, &event)
+				if err != nil {
+					return err
+				}
+
+				if !event.Consents.News {
+					return nil
+				}
+
+				fmt.Println("Adding user", event.UserID, "to the news list")
+
+				return nil
+			},
+		)
+	}
+
+	router.AddConsumerHandler(
+		"OnUserSignedUp-3",
+		"UserSignedUp-3",
+		subscriber,
+		func(msg *message.Message) error {
+			var event common.UserSignedUp
+			err := json.Unmarshal(msg.Payload, &event)
+			if err != nil {
+				return err
+			}
+
+			if !event.Consents.Marketing {
+				return nil
+			}
+
+			fmt.Println("Adding user", event.UserID, "to the promotions list")
+
+			return nil
+		},
+	)
+
+	router.AddConsumerHandler(
+		"OnUserSignedUp-4",
+		"UserSignedUp-4",
+		newsletterServiceGroupSubscriber,
+		func(msg *message.Message) error {
+			var event common.UserSignedUp
+			err := json.Unmarshal(msg.Payload, &event)
+			if err != nil {
+				return err
+			}
+
+			if !event.Consents.Marketing {
+				return nil
+			}
+
+			fmt.Println("Adding user", event.UserID, "to the promotions list")
+
+			return nil
+		},
+	)
+
+	router.AddConsumerHandler(
+		"AddToPromotionsList-7",
+		"UserSignedUp-7",
+		addToPromotionsListGroupSubscriber,
+		func(msg *message.Message) error {
+			var event common.UserSignedUp
+			err := json.Unmarshal(msg.Payload, &event)
+			if err != nil {
+				return err
+			}
+
+			if !event.Consents.Marketing {
+				return nil
+			}
+
+			fmt.Println("Adding user", event.UserID, "to the promotions list")
+
+			return nil
+		},
+	)
+
+	router.AddConsumerHandler(
+		"AddToNewsList-7",
+		"UserSignedUp-7",
+		addToNewsListGroupSubscriber,
+		func(msg *message.Message) error {
+			var event common.UserSignedUp
+			err := json.Unmarshal(msg.Payload, &event)
+			if err != nil {
+				return err
+			}
+
+			if !event.Consents.News {
+				return nil
+			}
+
+			fmt.Println("Adding user", event.UserID, "to the news list")
+
+			return nil
+		},
+	)
+
+	if replica == "1" {
+		eventProc8, err := cqrs.NewEventProcessorWithConfig(router, cqrs.EventProcessorConfig{
+			GenerateSubscribeTopic: func(params cqrs.EventProcessorGenerateSubscribeTopicParams) (string, error) {
+				return fmt.Sprintf("%s-8", params.EventName), nil
+			},
+			SubscriberConstructor: func(params cqrs.EventProcessorSubscriberConstructorParams) (message.Subscriber, error) {
+				handlerName := strings.Split(params.HandlerName, "-")[0]
+				return redisstream.NewSubscriber(
+					redisstream.SubscriberConfig{
+						Client:        subClient,
+						ConsumerGroup: fmt.Sprintf("%s_%s", serviceName, handlerName),
+					},
+					logger,
+				)
+			},
+			Marshaler: cqrs.JSONMarshaler{
+				GenerateName: cqrs.StructName,
+			},
+			Logger: logger,
+		})
+		if err != nil {
+			panic(err)
+		}
+		err = eventProc8.AddHandlers(
+			cqrs.NewEventHandler("AddToPromotionsList-8", HandlePromotions),
+			cqrs.NewEventHandler("AddToNewsList-8", HandleNews),
+		)
+		if err != nil {
+			panic(err)
+		}
+	}
+
+	eventProc9, err := cqrs.NewEventProcessorWithConfig(router, cqrs.EventProcessorConfig{
+		GenerateSubscribeTopic: func(params cqrs.EventProcessorGenerateSubscribeTopicParams) (string, error) {
+			return fmt.Sprintf("%s-9", params.EventName), nil
+		},
+		SubscriberConstructor: func(params cqrs.EventProcessorSubscriberConstructorParams) (message.Subscriber, error) {
+			handlerName := strings.Split(params.HandlerName, "-")[0]
+			return redisstream.NewSubscriber(
+				redisstream.SubscriberConfig{
+					Client:        subClient,
+					ConsumerGroup: fmt.Sprintf("%s_%s", serviceName, handlerName),
+				},
+				logger,
+			)
+		},
+		Marshaler: cqrs.JSONMarshaler{
+			GenerateName: cqrs.StructName,
+		},
+		Logger: logger,
+	})
+	if err != nil {
+		panic(err)
+	}
+
+	err = eventProc9.AddHandlers(
+		cqrs.NewEventHandler("AddToPromotionsList-9", HandlePromotions),
+		cqrs.NewEventHandler("AddToNewsList-9", HandleNews),
+	)
+	if err != nil {
+		panic(err)
+	}
+
+	err = router.Run(context.Background())
+	if err != nil {
+		panic(err)
+	}
+}
+
+func HandleNews(ctx context.Context, e *common.UserSignedUp) error {
+	if !e.Consents.News {
+		return nil
+	}
+
+	fmt.Println("Adding user", e.UserID, "to the news list")
+
+	return nil
+}
+
+func HandlePromotions(ctx context.Context, e *common.UserSignedUp) error {
+	if !e.Consents.Marketing {
+		return nil
+	}
+
+	fmt.Println("Adding user", e.UserID, "to the promotions list")
+
+	return nil
+}