Add demo

README.md

@@ -11,4 +11,32 @@ docker compose up --build
 docker compose run auth-cli /app/auth-cli-bin -action create -username demo-user
 ```
 
-### Access Grafana dashboard: localhost:3002/d/realtime-metrics-dashboard
+### Connect to the services to start playing
+
+Using websocat for the example but you can use any other tool of your preference
+```
+websocat ws://localhost:3000/publish -H "Authorization: Bearer {JTW_TOKEN}"
+
+websocat ws://localhost:3001/subscribe -H "Authorization: Bearer {JTW_TOKEN}"
+```
+
+### To access metrics dashboard click in the following link: [Metrics Dashboard](http://localhost:3002/d/realtime-metrics-dashboard)
+
+### Demo
+
+Build and run the project:
+```
+docker compose up --build
+```
+
+##### Obtain a JWT token and run demo container
+
+Linux:
+```
+JWT_TOKEN=$(docker compose run --rm auth-cli /app/auth-cli-bin -action create -username demo-user | grep "generated JWT" | awk -F': ' '{print $2}') && docker compose run --rm -e JWT_TOKEN="$JWT_TOKEN" demo /app/demo-bin
+```
+
+Windows Powershell:
+```
+$JWT_TOKEN = (docker compose run --rm auth-cli /app/auth-cli-bin -action create -username demo-user | Select-String "generated JWT" | ForEach-Object { $_.Line -replace ".*: ", "" }); docker compose run --rm -e JWT_TOKEN=$JWT_TOKEN demo /app/demo-bin
+```

demo/main.go

@@ -0,0 +1,101 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+	"os"
+	"sync"
+	"time"
+
+	"github.com/gorilla/websocket"
+)
+
+const (
+	publisherURL    = "ws://publisher:3000/publish"
+	subscribeURL    = "ws://subscriber:3001/subscribe"
+	messageInterval = 1 * time.Second
+	maxMessages     = 10
+)
+
+func main() {
+	jwtToken := os.Getenv("JWT_TOKEN")
+	if jwtToken == "" {
+		log.Fatalf("JWT_TOKEN environment variable not set")
+	}
+
+	var wg sync.WaitGroup
+
+	// wait for subscriber to connect and to be ready
+	wg.Add(1)
+	go startSubscriber(jwtToken, &wg)
+	wg.Wait()
+
+	publishMessages(jwtToken, &wg)
+
+	// wait for all messages to be received
+	wg.Wait()
+
+	log.Println("Demo completed: all 10 messages sent and received")
+}
+
+func connectWebSocket(url, jwtToken string) (*websocket.Conn, error) {
+	dialer := websocket.Dialer{}
+	header := http.Header{}
+	header.Set("Authorization", fmt.Sprintf("Bearer %s", jwtToken))
+
+	conn, _, err := dialer.Dial(url, header)
+	if err != nil {
+		return nil, fmt.Errorf("failed to connect to WebSocket endpoint %s: %v", url, err)
+	}
+	return conn, nil
+}
+
+func startSubscriber(jwtToken string, wg *sync.WaitGroup) {
+	conn, err := connectWebSocket(subscribeURL, jwtToken)
+	if err != nil {
+		log.Fatalf("failed to connect to subscribe endpoint: %v", err)
+	}
+	defer conn.Close()
+
+	log.Println("connected to subscribe ws, waiting for messages...")
+	wg.Done()
+
+	count := 0
+	for {
+		_, message, err := conn.ReadMessage()
+		if err != nil {
+			log.Printf("ws read error: %v", err)
+			break
+		}
+		fmt.Printf("received message from subscribe: %s\n", string(message))
+		count++
+		if count == maxMessages {
+			wg.Done()
+			break
+		}
+	}
+}
+
+func publishMessages(jwtToken string, wg *sync.WaitGroup) {
+	conn, err := connectWebSocket(publisherURL, jwtToken)
+	if err != nil {
+		log.Fatalf("failed to connect to publish ws: %v", err)
+	}
+	defer conn.Close()
+
+	wg.Add(1)
+	for i := range [maxMessages]int{} {
+		message := fmt.Sprintf("demo message #%d", i)
+		fmt.Printf("sending message: %s\n", message)
+
+		err := conn.WriteMessage(websocket.TextMessage, []byte(message))
+		if err != nil {
+			log.Printf("failed to send message via publish WebSocket: %v", err)
+		} else {
+			log.Println("message published successfully")
+		}
+
+		time.Sleep(messageInterval)
+	}
+}

docker-compose.yml

@@ -46,3 +46,10 @@ services:
     build:
       context: .
       dockerfile: docker/auth-cli/Dockerfile
+  demo:
+    build:
+      context: .
+      dockerfile: docker/demo/Dockerfile
+    depends_on:
+      - publisher
+      - subscriber

docker/demo/Dockerfile

@@ -0,0 +1,10 @@
+FROM golang:1.24.2-alpine
+
+WORKDIR /app
+
+COPY demo/ ./demo
+COPY go.mod go.sum ./
+
+RUN go mod download
+
+RUN CGO_ENABLED=0 GOOS=linux go build -o demo-bin -ldflags "-s -w" ./demo/