subscribe: set client_id for MQTT subscriber to ensure unique identification

internal/handler/mqttping.go

@@ -1,24 +1,24 @@
 package handler
 
 import (
-    "net/http"
-    "os"
-    "time"
+	"net/http"
+	"os"
+	"time"
 
-    "github.com/gin-gonic/gin"
-    "git.piskot.si/SeminarM2/lambdaiot-core/internal/mqtt"
+	"git.piskot.si/SeminarM2/lambdaiot-core/internal/mqtt"
+	"github.com/gin-gonic/gin"
 )
 
 // MQTTPing publishes the current timestamp to the configured MQTT topic
 func MQTTPing(c *gin.Context) {
-    ts := time.Now().Format(time.RFC3339)
-    topic := os.Getenv("MQTT_TOPIC")
-    if topic == "" {
-        topic = "lambdaiot"
-    }
-    if err := mqtt.PublishDefault(topic, []byte(ts)); err != nil {
-        c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
-        return
-    }
-    c.JSON(http.StatusOK, gin.H{"timestamp": ts})
+	ts := time.Now().Format(time.RFC3339)
+	topic := os.Getenv("MQTT_TOPIC")
+	if topic == "" {
+		topic = "lambdaiot"
+	}
+	if err := mqtt.PublishDefault(topic, []byte(ts)); err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+	c.JSON(http.StatusOK, gin.H{"timestamp": ts})
 }

test/subscribe.py

@@ -32,6 +32,7 @@ client.on_connect = on_connect
 client.on_message = on_message
 if username:
     client.username_pw_set(username, password)
+    client.client_id = f"subscribe-{os.getpid()}"
 
 try:
     client.connect(host, port, 60)