add basic mqtt client

internal/processing/mqtt-message-encode.go

@@ -0,0 +1,35 @@
+package processing
+
+import (
+	"context"
+	"fmt"
+
+	mqtt "github.com/eclipse/paho.mqtt.golang"
+)
+
+type MQTTMessageEncode struct {
+	config ProcessorConfig
+}
+
+func (mme *MQTTMessageEncode) Process(ctx context.Context, payload any) (any, error) {
+	payloadMessage, ok := payload.(mqtt.Message)
+
+	if !ok {
+		return nil, fmt.Errorf("mqtt.message.encode processor only accepts an mqtt.Message")
+	}
+
+	return payloadMessage.Payload(), nil
+}
+
+func (mme *MQTTMessageEncode) Type() string {
+	return mme.config.Type
+}
+
+func init() {
+	RegisterProcessor(ProcessorRegistration{
+		Type: "mqtt.message.encode",
+		New: func(config ProcessorConfig) (Processor, error) {
+			return &MQTTMessageEncode{config: config}, nil
+		},
+	})
+}