Make NATS more verbose

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <[email protected]>

main.go

@@ -4,6 +4,8 @@
 package main
 
 import (
+	"log"
+
 	"github.com/openfaas-incubator/connector-sdk/types"
 	"github.com/openfaas-incubator/nats-connector/config"
 	"github.com/openfaas-incubator/nats-connector/nats"
@@ -29,9 +31,17 @@ func main() {
 
 	brokerConfig := nats.BrokerConfig{
 		Host:        config.Broker,
-		ConnTimeout: config.UpstreamTimeout,
+		ConnTimeout: config.UpstreamTimeout, // ConnTimeout isn't the same as UpstreamTimeout, it's just the delay to connect to NATS.
 	}
 
-	broker := nats.NewBroker(brokerConfig)
-	broker.Subscribe(controller, config.Topics)
+	broker, err := nats.NewBroker(brokerConfig)
+
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	err = broker.Subscribe(controller, config.Topics)
+	if err != nil {
+		log.Fatal(err)
+	}
 }

nats/broker.go

@@ -4,6 +4,7 @@
 package nats
 
 import (
+	"fmt"
 	"log"
 	"sync"
 	"time"
@@ -13,30 +14,41 @@ import (
 )
 
 const queueGroup = "openfaas_nats_worker_group"
+
 const clientName = "openfaas_connector"
 
 // BrokerConfig high level config for the broker
 type BrokerConfig struct {
-	Host        string
+
+	// Host is the NATS address, the port is hard-coded to 4222
+	Host string
+
+	// ConnTimeout is the timeout for Dial on a connection.
 	ConnTimeout time.Duration
 }
 
 // Broker used to subscribe to NATS subjects
 type Broker interface {
-	Subscribe(types.Controller, []string)
+	Subscribe(types.Controller, []string) error
 }
 
 type broker struct {
 	client *nats.Conn
 }
 
+// NATSPort hard-coded port for NATS
+const NATSPort = "4222"
+
 // NewBroker loops until we are able to connect to the NATS server
-func NewBroker(config BrokerConfig) Broker {
+func NewBroker(config BrokerConfig) (Broker, error) {
 	broker := &broker{}
+	brokerURL := fmt.Sprintf("nats://%s:%s", config.Host, NATSPort)
 
-	brokerURL := "nats://" + config.Host + ":4222"
 	for {
-		client, err := nats.Connect(brokerURL, nats.Timeout(config.ConnTimeout), nats.Name(clientName))
+		client, err := nats.Connect(brokerURL,
+			nats.Timeout(config.ConnTimeout),
+			nats.Name(clientName))
+
 		if client != nil && err == nil {
 			broker.client = client
 			break
@@ -45,30 +57,50 @@ func NewBroker(config BrokerConfig) Broker {
 		if client != nil {
 			client.Close()
 		}
+
 		log.Println("Wait for brokers to come up.. ", brokerURL)
 		time.Sleep(1 * time.Second)
 		// TODO Add healthcheck
 	}
-	return broker
+
+	return broker, nil
 }
 
 // Subscribe to a list of NATS subjects and block until interrupted
-func (b *broker) Subscribe(controller types.Controller, topics []string) {
+func (b *broker) Subscribe(controller types.Controller, topics []string) error {
 	log.Printf("Configured topics: %v", topics)
 
+	if b.client == nil {
+		return fmt.Errorf("client was nil, try to reconnect")
+	}
+
 	wg := sync.WaitGroup{}
 	wg.Add(1)
 
+	subs := []*nats.Subscription{}
 	for _, topic := range topics {
-		log.Printf("Binding to topic: %v", topic)
-		// check client not nil
-		b.client.QueueSubscribe(topic, queueGroup, func(m *nats.Msg) {
-			log.Printf("Received topic: %s, message: %s", m.Subject, string(m.Data))
+		log.Printf("Binding to topic: %q", topic)
+
+		sub, err := b.client.QueueSubscribe(topic, queueGroup, func(m *nats.Msg) {
+			log.Printf("Topic: %s, message: %q", m.Subject, string(m.Data))
+
 			controller.Invoke(m.Subject, &m.Data)
 		})
+		subs = append(subs, sub)
+
+		if err != nil {
+			log.Printf("Unable to bind to topic: %s", topic)
+		}
+	}
+
+	for _, sub := range subs {
+		log.Printf("Subscription: %s ready", sub.Subject)
 	}
 
 	// interrupt handling
 	wg.Wait()
+
 	b.client.Close()
+
+	return nil
 }