Ensure the closing of connections

The problem was that the connection was kept open on channel errors.
We therefore ran into open file count limits.

main.go

@@ -23,7 +23,7 @@ var (
 	).Author(
 		"Lukas Burgey",
 	).Version(
-		"v2.1.1",
+		"v2.1.2",
 	)
 	cmdStart         = app.Command("start", "Starts the client in its normal operation mode.").Default()
 	cmdDeregister    = app.Command("deregister", "Before disabling the client: Use deregister to inform the backend that the client ceases operation.")

source/amqp/amqp.go

@@ -8,7 +8,7 @@ import (
 	"time"
 
 	"git.scc.kit.edu/feudal/feudalClient/config"
-	"git.scc.kit.edu/feudal/feudalClient/deployments"
+	deps "git.scc.kit.edu/feudal/feudalClient/deployments"
 	"github.com/streadway/amqp"
 )
 
@@ -32,24 +32,36 @@ func (src *Source) connect() (deliveries <-chan amqp.Delivery, closed <-chan *am
 		channel *amqp.Channel
 		queue   amqp.Queue
 	)
+
+	closeConn := func() {
+		log.Printf("[AMQP] Closing connection after an error (logs will follow)")
+		closeErr := src.connection.Close()
+		if closeErr != nil {
+			log.Printf("[AMQP] Error closing connection: %s", closeErr)
+		}
+	}
 	// open connection
 	src.connection, err = amqp.Dial(src.uri())
 	if err != nil {
 		return
 	}
 
-	// closed signals a closing of the connection
-	closed = src.connection.NotifyClose(make(chan *amqp.Error))
-
 	channel, err = src.connection.Channel()
 	if err != nil {
+		closeConn()
 		return
 	}
+	// closed signals the  closing of the connection / channel
+	closed = channel.NotifyClose(make(chan *amqp.Error))
 
-	// puts this channel into confirm mode
-	channel.Confirm(
+	// put the channel into confirm mode
+	err = channel.Confirm(
 		false, // noWait
 	)
+	if err != nil {
+		closeConn()
+		return
+	}
 
 	// the queue we connect to the topic exchange
 	queue, err = channel.QueueDeclare(
@@ -61,6 +73,7 @@ func (src *Source) connect() (deliveries <-chan amqp.Delivery, closed <-chan *am
 		nil,   // arguments
 	)
 	if err != nil {
+		closeConn()
 		return
 	}
 
@@ -70,13 +83,15 @@ func (src *Source) connect() (deliveries <-chan amqp.Delivery, closed <-chan *am
 			log.Printf("[AMQP] Binding to '%s' with routing keys %v", exchange.name, exchange.bindingKeys)
 		}
 		for _, bindingKey := range exchange.bindingKeys {
-			if err = channel.QueueBind(
+			err = channel.QueueBind(
 				queue.Name,    // queue name
 				bindingKey,    // routing key
 				exchange.name, // exchange
 				false,         // no-wait
 				nil,
-			); err != nil {
+			)
+			if err != nil {
+				closeConn()
 				err = fmt.Errorf("Error binding %s:\n\t%s", bindingKey, err)
 				return
 			}
@@ -93,6 +108,7 @@ func (src *Source) connect() (deliveries <-chan amqp.Delivery, closed <-chan *am
 		nil,        // args
 	)
 	if err != nil {
+		closeConn()
 		return
 	}
 
@@ -203,7 +219,7 @@ func (src *Source) Connect() (sink <-chan deps.Dep, err error) {
 				// Wait for the connection to close
 				select {
 				case connectionError := <-closed:
-					log.Printf("[AMQP] Connection closed: %s", connectionError)
+					log.Printf("[AMQP] Connection/Channel closed: %s", connectionError)
 				}
 			}