Manager: consistent MQTT server/broker naming

Consistently log about the MQTT "broker", not the "server". The former
is common MQTT terminology.

internal/manager/eventbus/mqtt_client.go

@@ -11,6 +11,7 @@ import (
 
 	"github.com/eclipse/paho.golang/autopaho"
 	"github.com/eclipse/paho.golang/paho"
+	"github.com/rs/zerolog"
 	"github.com/rs/zerolog/log"
 )
 
@@ -54,12 +55,12 @@ func NewMQTTForwarder(config MQTTClientConfig) *MQTTForwarder {
 		config.ClientID = defaultClientID
 	}
 
-	serverURL, err := url.Parse(config.BrokerURL)
+	brokerURL, err := url.Parse(config.BrokerURL)
 	if err != nil {
 		log.Error().
 			Err(err).
-			Str("mqttServerURL", config.BrokerURL).
+			Str("brokerURL", config.BrokerURL).
-			Msg("could not parse MQTT server URL, skipping creation of MQTT client")
+			Msg("mqtt client: could not parse MQTT broker URL, skipping creation of MQTT client")
 		return nil
 	}
 
@@ -67,7 +68,7 @@ func NewMQTTForwarder(config MQTTClientConfig) *MQTTForwarder {
 		topicPrefix: config.TopicPrefix,
 	}
 	client.config = autopaho.ClientConfig{
-		BrokerUrls:        []*url.URL{serverURL},
+		BrokerUrls:        []*url.URL{brokerURL},
 		KeepAlive:         keepAlive,
 		ConnectRetryDelay: connectRetryDelay,
 		OnConnectionUp:    client.onConnectionUp,
@@ -84,7 +85,7 @@ func NewMQTTForwarder(config MQTTClientConfig) *MQTTForwarder {
 }
 
 func (m *MQTTForwarder) Connect(ctx context.Context) {
-	log.Debug().Msg("mqtt client: connecting")
+	m.logger().Debug().Msg("mqtt client: connecting to broker")
 	conn, err := autopaho.NewConnection(ctx, m.config)
 	if err != nil {
 		panic(err)
@@ -92,34 +93,35 @@ func (m *MQTTForwarder) Connect(ctx context.Context) {
 
 	m.conn = conn
 	m.ctx = ctx
+
 }
 
 func (m *MQTTForwarder) onConnectionUp(connMgr *autopaho.ConnectionManager, connAck *paho.Connack) {
-	log.Info().Msg("mqtt client: connection established")
+	m.logger().Info().Msg("mqtt client: connection established")
 }
 
 func (m *MQTTForwarder) onConnectionError(err error) {
-	log.Warn().AnErr("cause", err).Msg("mqtt client: could not connect to MQTT server")
+	m.logger().Warn().AnErr("cause", err).Msg("mqtt client: could not connect to MQTT broker")
 }
 
 func (m *MQTTForwarder) onClientError(err error) {
-	log.Warn().AnErr("cause", err).Msg("mqtt client: server requested disconnect")
+	m.logger().Warn().AnErr("cause", err).Msg("mqtt client: broker requested disconnect")
 }
 
 func (m *MQTTForwarder) onServerDisconnect(d *paho.Disconnect) {
-	logEntry := log.Warn()
+	logEntry := m.logger().Warn()
 	if d.Properties != nil {
 		logEntry = logEntry.Str("reason", d.Properties.ReasonString)
 	} else {
 		logEntry = logEntry.Int("reasonCode", int(d.ReasonCode))
 	}
-	logEntry.Msg("mqtt client: server requested disconnect")
+	logEntry.Msg("mqtt client: broker requested disconnect")
 }
 
 func (m *MQTTForwarder) Broadcast(topic EventTopic, payload interface{}) {
 	fullTopic := m.topicPrefix + string(topic)
 
-	logger := log.With().
+	logger := m.logger().With().
 		Str("topic", fullTopic).
 		// Interface("event", payload).
 		Logger()
@@ -144,12 +146,24 @@ func (m *MQTTForwarder) Broadcast(topic EventTopic, payload interface{}) {
 			logger.Error().AnErr("cause", err).Msg("mqtt client: error publishing event")
 			return
 		case pr.ReasonCode == 16:
-			logger.Debug().Msg("mqtt client: event sent to server, but there were no subscribers")
+			logger.Debug().Msg("mqtt client: event sent to broker, but there were no subscribers")
 			return
 		case pr.ReasonCode != 0:
-			logger.Warn().Int("reasonCode", int(pr.ReasonCode)).Msg("mqtt client: event rejected by mqtt server")
+			logger.Warn().Int("reasonCode", int(pr.ReasonCode)).Msg("mqtt client: event rejected by mqtt broker")
 		default:
-			logger.Debug().Msg("mqtt client: event sent to server")
+			logger.Debug().Msg("mqtt client: event sent to broker")
 		}
 	}(fullTopic, asJSON)
 }
+
+func (m *MQTTForwarder) logger() *zerolog.Logger {
+	logCtx := log.With()
+
+	if len(m.config.BrokerUrls) > 0 {
+		// Assumption: there's no more than one broker URL.
+		logCtx = logCtx.Stringer("broker", m.config.BrokerUrls[0])
+	}
+
+	logger := logCtx.Logger()
+	return &logger
+}