Add convenience function to set connection name (#108)

* Add convenience function to set connection name

RabbitMQ reads the connection property "connection_name" from the client
and displays the value in the Management UI. This is convenient for
debugging and locating specific client connections, and correlating a
connection to an app.

Showed in the examples how to use this function and added an example in
Go Docs.

Signed-off-by: Aitor Perez Cedres <acedres@vmware.com>

* Minor refactor to use const string

Signed-off-by: Aitor Perez Cedres <acedres@vmware.com>
Co-authored-by: Luke Bakken <luke@bakken.io>

_examples/simple-consumer/consumer.go

@@ -66,7 +66,7 @@ type Consumer struct {
 }
 
 func SetupCloseHandler(consumer *Consumer) {
-	c := make(chan os.Signal)
+	c := make(chan os.Signal, 2)
 	signal.Notify(c, os.Interrupt, syscall.SIGTERM)
 	go func() {
 		<-c
@@ -88,8 +88,10 @@ func NewConsumer(amqpURI, exchange, exchangeType, queueName, key, ctag string) (
 
 	var err error
 
+	config := amqp.Config{Properties: amqp.NewConnectionProperties()}
+	config.Properties.SetClientConnectionName("sample-consumer")
 	Log.Printf("dialing %q", amqpURI)
-	c.conn, err = amqp.Dial(amqpURI)
+	c.conn, err = amqp.DialConfig(amqpURI, config)
 	if err != nil {
 		return nil, fmt.Errorf("Dial: %s", err)
 	}

_examples/simple-producer/producer.go

@@ -42,7 +42,7 @@ func main() {
 }
 
 func SetupCloseHandler(done chan bool) {
-	c := make(chan os.Signal)
+	c := make(chan os.Signal, 2)
 	signal.Notify(c, os.Interrupt, syscall.SIGTERM)
 	go func() {
 		<-c
@@ -55,8 +55,10 @@ func publish(done chan bool, amqpURI, exchange, exchangeType, routingKey, body s
 	// This function dials, connects, declares, publishes, and tears down,
 	// all in one go. In a real service, you probably want to maintain a
 	// long-lived connection as state, and publish against that.
+	config := amqp.Config{Properties: amqp.NewConnectionProperties()}
+	config.Properties.SetClientConnectionName("sample-producer")
 	Log.Printf("dialing %q", amqpURI)
-	connection, err := amqp.Dial(amqpURI)
+	connection, err := amqp.DialConfig(amqpURI, config)
 	if err != nil {
 		return fmt.Errorf("Dial: %s", err)
 	}

connection.go

@@ -76,6 +76,13 @@ type Config struct {
 	Dial func(network, addr string) (net.Conn, error)
 }
 
+// NewConnectionProperties initialises an amqp.Table struct to empty value. This
+// amqp.Table can be used as Properties in amqp.Config to set the connection
+// name, using amqp.DialConfig()
+func NewConnectionProperties() Table {
+	return make(Table)
+}
+
 // Connection manages the serialization and deserialization of frames from IO
 // and dispatches the frames to the appropriate channel.  All RPC methods and
 // asynchronous Publishing, Delivery, Ack, Nack and Return messages are

connection_test.go

@@ -268,3 +268,20 @@ func TestReaderGoRoutineTerminatesWhenMsgIsProcessedDuringClose(t *testing.T) {
 	t.Log("waiting for go-routines to terminate")
 	wg.Wait()
 }
+
+func TestConnectionConfigPropertiesWithClientProvidedConnectionName(t *testing.T) {
+	const expectedConnectionName = "amqp091-go-test"
+
+	connectionProperties := NewConnectionProperties()
+	connectionProperties.SetClientConnectionName(expectedConnectionName)
+
+	currentConnectionName, ok := connectionProperties["connection_name"]
+	if !ok {
+		t.Fatal("Connection name was not set by Table.SetClientConnectionName")
+	}
+	if currentConnectionName != expectedConnectionName {
+		t.Fatalf("Connection name is set to: %s. Expected: %s",
+			currentConnectionName,
+			expectedConnectionName)
+	}
+}

examples_test.go

@@ -422,3 +422,15 @@ func ExampleConnection_NotifyBlocked() {
 	// Your application domain channel setup publishings
 	publishAllTheThings(conn)
 }
+
+func ExampleTable_SetClientConnectionName() {
+	// Sets the well-known connection_name property in amqp.Config. The connection
+	// name will be visible in RabbitMQ Management UI.
+	config := amqp.Config{Properties: amqp.NewConnectionProperties()}
+	config.Properties.SetClientConnectionName("my-client-app")
+	conn, err := amqp.Dial("amqp://guest:guest@localhost:5672/")
+	if err != nil {
+		log.Fatalf("connection.open: %s", err)
+	}
+	defer conn.Close()
+}

types.go

@@ -268,6 +268,14 @@ func (t Table) Validate() error {
 	return validateField(t)
 }
 
+// Sets the connection name property. This property can be used in
+// amqp.Config to set a custom connection name during amqp.DialConfig(). This
+// can be helpful to identify specific connections in RabbitMQ, for debugging or
+// tracing purposes.
+func (t Table) SetClientConnectionName(connName string) {
+	t["connection_name"] = connName
+}
+
 type message interface {
 	id() (uint16, uint16)
 	wait() bool