Major Refactoring for Enhanced Performance and Readability

.env-example

@@ -1 +1,8 @@
-SLACK_WEBHOOK_URL=
+	defaultBindAddr=:8080
+	defaultMetricsBindAddr=:8081
+	defaultGrafanaURL=http://grafana:3000
+	defaultGrafanaCredentials=admin:secret
+	defaultAMQPURI=amqp://guest:guest@rabbitmq:5672/
+	defaultAMQPQueue=deployments
+	defaultKafkaBrokers=kafka:9092
+	defaultKafkaTopic=events

README.md

@@ -1,4 +1,4 @@
-# Event-Driven application example
+# Event Driven Architecture with Golang (Example)
 
 This is an example Event-Driven application written in Go, using [Watermill](https://github.com/ThreeDotsLabs/watermill).
 
@@ -8,7 +8,7 @@ demonstrate working with multiple event streams.
 
 ![](https://threedots.tech/media/event-driven-applications/diagram.png)
 
-An example result can look like this: 
+An example result can look like this:
 
 ![](https://threedots.tech/media/event-driven-applications/grafana.png)
 
@@ -21,10 +21,10 @@ webhook URL in `SLACK_WEBHOOK_URL` variable.
 
 In addition to the application, the docker-compose environment consists of:
 
-* **Kafka** and **ZooKeeper**
-* **RabbitMQ**
-* **Grafana**
-* **Prometheus**
+- **Kafka** and **ZooKeeper**
+- **RabbitMQ**
+- **Grafana**
+- **Prometheus**
 
 The whole environment can be run with:
 

app/Dockerfile

@@ -0,0 +1,18 @@
+# Step 1: Modules caching
+FROM golang:1.21.4-alpine3.18 as modules
+COPY go.mod go.sum /modules/
+WORKDIR /modules
+RUN go mod download
+
+# Step 2: Builder
+FROM golang:1.21.4-alpine3.18 as builder
+COPY --from=modules /go/pkg /go/pkg
+COPY . /app
+WORKDIR /app
+RUN CGO_ENABLED=0 GOOS=linux GOARCH=arm64 \
+    go build -tags migrate -o /bin/app ./cmd/app
+
+# Step 3: Final
+FROM scratch
+COPY --from=builder /bin/app /app
+CMD ["/app"]

cmd/main.go → app/cmd/app/main.go

@@ -1,37 +1,52 @@
 package main
 
 import (
-	"github.com/ThreeDotsLabs/event-driven-example/pkg"
+	"context"
 
+	"github.com/ThreeDotsLabs/event-driven-example/config"
+	"github.com/ThreeDotsLabs/event-driven-example/internal"
 	"github.com/ThreeDotsLabs/watermill"
 	"github.com/ThreeDotsLabs/watermill/components/metrics"
 	"github.com/ThreeDotsLabs/watermill/message"
 	"github.com/ThreeDotsLabs/watermill/message/router/middleware"
 )
 
 func main() {
+	// Create a new context and add a cancel function to it.
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	// Create a new logger.
 	logger := watermill.NewStdLogger(false, false)
-	config := pkg.LoadConfig()
+	c := config.LoadConfig()
 
+	// Create a new router.
 	router, err := message.NewRouter(message.RouterConfig{}, logger)
 	if err != nil {
 		panic(err)
 	}
 	router.AddMiddleware(middleware.Recoverer)
 
-	// Metrics setup
-	prometheusRegistry, closeMetricsServer := metrics.CreateRegistryAndServeHTTP(config.MetricsBindAddr)
+	// Create a new Prometheus registry and serve it on the given address.
+	prometheusRegistry, closeMetricsServer := metrics.CreateRegistryAndServeHTTP(c.MetricsBindAddr)
 	defer closeMetricsServer()
 	metricsBuilder := metrics.NewPrometheusMetricsBuilder(prometheusRegistry, "", "")
 	metricsBuilder.AddPrometheusRouterMetrics(router)
 
-	err = pkg.SetupRouter(router, config, logger)
+	// Setup the router.
+	r := &internal.Router{
+		Router: router,
+		Logger: logger,
+		Config: c,
+	}
+	err = r.SetupRouter()
 	if err != nil {
 		panic(err)
 	}
 
-	err = router.Run()
-	if err != nil {
+	// Run the router.
+	if err := router.Run(ctx); err != nil {
 		panic(err)
 	}
+
 }

pkg/config.go → app/config/config.go

@@ -1,4 +1,4 @@
-package pkg
+package config
 
 import (
 	"os"
@@ -23,15 +23,15 @@ type Config struct {
 	BindAddr        string
 	MetricsBindAddr string
 
+	GrafanaURL         string
+	GrafanaCredentials string
+
 	AMQPURI   string
 	AMQPQueue string
 
 	KafkaBrokers []string
 	KafkaTopic   string
 
-	GrafanaURL         string
-	GrafanaCredentials string
-
 	SlackWebhookURL string
 }
 

app/go.mod

@@ -0,0 +1,57 @@
+module github.com/ThreeDotsLabs/event-driven-example
+
+go 1.21
+
+require (
+	github.com/ThreeDotsLabs/watermill v1.3.5
+	github.com/ThreeDotsLabs/watermill-amqp v1.1.4
+	github.com/ThreeDotsLabs/watermill-http v1.1.4
+	github.com/ThreeDotsLabs/watermill-kafka/v2 v2.5.0
+)
+
+require (
+	github.com/Shopify/sarama v1.38.0 // indirect
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cenkalti/backoff/v3 v3.2.2 // indirect
+	github.com/cespare/xxhash/v2 v2.2.0 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/eapache/go-resiliency v1.3.0 // indirect
+	github.com/eapache/go-xerial-snappy v0.0.0-20180814174437-776d5712da21 // indirect
+	github.com/eapache/queue v1.1.0 // indirect
+	github.com/go-chi/chi v4.0.2+incompatible // indirect
+	github.com/go-chi/chi/v5 v5.0.8 // indirect
+	github.com/go-chi/render v1.0.1 // indirect
+	github.com/go-logr/logr v1.2.3 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
+	github.com/golang/protobuf v1.5.2 // indirect
+	github.com/golang/snappy v0.0.4 // indirect
+	github.com/google/uuid v1.3.1 // indirect
+	github.com/hashicorp/errwrap v1.1.0 // indirect
+	github.com/hashicorp/go-multierror v1.1.1 // indirect
+	github.com/hashicorp/go-uuid v1.0.3 // indirect
+	github.com/jcmturner/aescts/v2 v2.0.0 // indirect
+	github.com/jcmturner/dnsutils/v2 v2.0.0 // indirect
+	github.com/jcmturner/gofork v1.7.6 // indirect
+	github.com/jcmturner/gokrb5/v8 v8.4.3 // indirect
+	github.com/jcmturner/rpc/v2 v2.0.3 // indirect
+	github.com/klauspost/compress v1.15.11 // indirect
+	github.com/lithammer/shortuuid/v3 v3.0.7 // indirect
+	github.com/matttproud/golang_protobuf_extensions v1.0.4 // indirect
+	github.com/oklog/ulid v1.3.1 // indirect
+	github.com/pierrec/lz4/v4 v4.1.17 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
+	github.com/prometheus/client_golang v1.14.0 // indirect
+	github.com/prometheus/client_model v0.3.0 // indirect
+	github.com/prometheus/common v0.39.0 // indirect
+	github.com/prometheus/procfs v0.9.0 // indirect
+	github.com/rcrowley/go-metrics v0.0.0-20201227073835-cf1acfcdf475 // indirect
+	github.com/sony/gobreaker v0.5.0 // indirect
+	github.com/streadway/amqp v1.0.0 // indirect
+	go.opentelemetry.io/contrib/instrumentation/github.com/Shopify/sarama/otelsarama v0.31.0 // indirect
+	go.opentelemetry.io/otel v1.6.1 // indirect
+	go.opentelemetry.io/otel/trace v1.6.1 // indirect
+	golang.org/x/crypto v0.0.0-20220722155217-630584e8d5aa // indirect
+	golang.org/x/net v0.4.0 // indirect
+	golang.org/x/sys v0.4.0 // indirect
+	google.golang.org/protobuf v1.28.1 // indirect
+)