Rework mqtt_consumer connect/reconnect (#4846)

plugins/inputs/mqtt_consumer/mqtt_consumer.go

@@ -1,10 +1,10 @@
 package mqtt_consumer
 
 import (
+	"errors"
 	"fmt"
 	"log"
 	"strings"
-	"sync"
 	"time"
 
 	"github.com/influxdata/telegraf"
@@ -19,6 +19,14 @@ import (
 // 30 Seconds is the default used by paho.mqtt.golang
 var defaultConnectionTimeout = internal.Duration{Duration: 30 * time.Second}
 
+type ConnectionState int
+
+const (
+	Disconnected ConnectionState = iota
+	Connecting
+	Connected
+)
+
 type MQTTConsumer struct {
 	Servers           []string
 	Topics            []string
@@ -36,16 +44,10 @@ type MQTTConsumer struct {
 	ClientID          string `toml:"client_id"`
 	tls.ClientConfig
 
-	sync.Mutex
 	client     mqtt.Client
-	// channel of all incoming raw mqtt messages
-	in   chan mqtt.Message
-	done chan struct{}
-
-	// keep the accumulator internally:
 	acc        telegraf.Accumulator
-
+	state      ConnectionState
-	connected bool
+	subscribed bool
 }
 
 var sampleConfig = `
@@ -110,22 +112,19 @@ func (m *MQTTConsumer) SetParser(parser parsers.Parser) {
 }
 
 func (m *MQTTConsumer) Start(acc telegraf.Accumulator) error {
-	m.Lock()
+	m.state = Disconnected
-	defer m.Unlock()
-	m.connected = false
 
 	if m.PersistentSession && m.ClientID == "" {
-		return fmt.Errorf("ERROR MQTT Consumer: When using persistent_session" +
+		return errors.New("persistent_session requires client_id")
-			" = true, you MUST also set client_id")
 	}
 
 	m.acc = acc
 	if m.QoS > 2 || m.QoS < 0 {
-		return fmt.Errorf("MQTT Consumer, invalid QoS value: %d", m.QoS)
+		return fmt.Errorf("qos value must be 0, 1, or 2: %d", m.QoS)
 	}
 
 	if m.ConnectionTimeout.Duration < 1*time.Second {
-		return fmt.Errorf("MQTT Consumer, invalid connection_timeout value: %s", m.ConnectionTimeout.Duration)
+		return fmt.Errorf("connection_timeout must be greater than 1s: %s", m.ConnectionTimeout.Duration)
 	}
 
 	opts, err := m.createOpts()
@@ -134,9 +133,7 @@ func (m *MQTTConsumer) Start(acc telegraf.Accumulator) error {
 	}
 
 	m.client = mqtt.NewClient(opts)
-	m.in = make(chan mqtt.Message, 1000)
+	m.state = Connecting
-	m.done = make(chan struct{})
-
 	m.connect()
 
 	return nil
@@ -145,52 +142,46 @@ func (m *MQTTConsumer) Start(acc telegraf.Accumulator) error {
 func (m *MQTTConsumer) connect() error {
 	if token := m.client.Connect(); token.Wait() && token.Error() != nil {
 		err := token.Error()
-		log.Printf("D! MQTT Consumer, connection error - %v", err)
+		m.state = Disconnected
-
 		return err
 	}
 
-	go m.receiver()
+	log.Printf("I! [inputs.mqtt_consumer]: connected %v", m.Servers)
+	m.state = Connected
 
-	return nil
+	// Only subscribe on first connection when using persistent sessions.  On
-}
+	// subsequent connections the subscriptions should be stored in the
-
+	// session, but the proper way to do this is to check the connection
-func (m *MQTTConsumer) onConnect(c mqtt.Client) {
+	// response to ensure a session was found.
-	log.Printf("I! MQTT Client Connected")
+	if !m.PersistentSession || !m.subscribed {
-	if !m.PersistentSession || !m.connected {
 		topics := make(map[string]byte)
 		for _, topic := range m.Topics {
 			topics[topic] = byte(m.QoS)
 		}
-		subscribeToken := c.SubscribeMultiple(topics, m.recvMessage)
+		subscribeToken := m.client.SubscribeMultiple(topics, m.recvMessage)
 		subscribeToken.Wait()
 		if subscribeToken.Error() != nil {
-			m.acc.AddError(fmt.Errorf("E! MQTT Subscribe Error\ntopics: %s\nerror: %s",
+			m.acc.AddError(fmt.Errorf("subscription error: topics: %s: %v",
 				strings.Join(m.Topics[:], ","), subscribeToken.Error()))
 		}
-		m.connected = true
+		m.subscribed = true
 	}
-	return
+
+	return nil
 }
 
 func (m *MQTTConsumer) onConnectionLost(c mqtt.Client, err error) {
-	m.acc.AddError(fmt.Errorf("E! MQTT Connection lost\nerror: %s\nMQTT Client will try to reconnect", err.Error()))
+	m.acc.AddError(fmt.Errorf("connection lost: %v", err))
+	log.Printf("D! [inputs.mqtt_consumer]: disconnected %v", m.Servers)
+	m.state = Disconnected
 	return
 }
 
-// receiver() reads all incoming messages from the consumer, and parses them into
+func (m *MQTTConsumer) recvMessage(c mqtt.Client, msg mqtt.Message) {
-// influxdb metric points.
-func (m *MQTTConsumer) receiver() {
-	for {
-		select {
-		case <-m.done:
-			return
-		case msg := <-m.in:
 	topic := msg.Topic()
 	metrics, err := m.parser.Parse(msg.Payload())
 	if err != nil {
-				m.acc.AddError(fmt.Errorf("E! MQTT Parse Error\nmessage: %s\nerror: %s",
+		m.acc.AddError(err)
-					string(msg.Payload()), err.Error()))
 	}
 
 	for _, metric := range metrics {
@@ -199,26 +190,20 @@ func (m *MQTTConsumer) receiver() {
 		m.acc.AddFields(metric.Name(), metric.Fields(), tags, metric.Time())
 	}
 }
-	}
-}
-
-func (m *MQTTConsumer) recvMessage(_ mqtt.Client, msg mqtt.Message) {
-	m.in <- msg
-}
 
 func (m *MQTTConsumer) Stop() {
-	m.Lock()
+	if m.state == Connected {
-	defer m.Unlock()
+		log.Printf("D! [inputs.mqtt_consumer]: disconnecting %v", m.Servers)
-
-	if m.connected {
-		close(m.done)
 		m.client.Disconnect(200)
-		m.connected = false
+		log.Printf("D! [inputs.mqtt_consumer]: disconnected %v", m.Servers)
+		m.state = Disconnected
 	}
 }
 
 func (m *MQTTConsumer) Gather(acc telegraf.Accumulator) error {
-	if !m.connected {
+	if m.state == Disconnected {
+		m.state = Connecting
+		log.Printf("D! [inputs.mqtt_consumer]: connecting %v", m.Servers)
 		m.connect()
 	}
 
@@ -261,7 +246,7 @@ func (m *MQTTConsumer) createOpts() (*mqtt.ClientOptions, error) {
 	for _, server := range m.Servers {
 		// Preserve support for host:port style servers; deprecated in Telegraf 1.4.4
 		if !strings.Contains(server, "://") {
-			log.Printf("W! mqtt_consumer server %q should be updated to use `scheme://host:port` format", server)
+			log.Printf("W! [inputs.mqtt_consumer] server %q should be updated to use `scheme://host:port` format", server)
 			if tlsCfg == nil {
 				server = "tcp://" + server
 			} else {
@@ -271,10 +256,9 @@ func (m *MQTTConsumer) createOpts() (*mqtt.ClientOptions, error) {
 
 		opts.AddBroker(server)
 	}
-	opts.SetAutoReconnect(true)
+	opts.SetAutoReconnect(false)
 	opts.SetKeepAlive(time.Second * 60)
 	opts.SetCleanSession(!m.PersistentSession)
-	opts.SetOnConnectHandler(m.onConnect)
 	opts.SetConnectionLostHandler(m.onConnectionLost)
 
 	return opts, nil
@@ -284,6 +268,7 @@ func init() {
 	inputs.Add("mqtt_consumer", func() telegraf.Input {
 		return &MQTTConsumer{
 			ConnectionTimeout: defaultConnectionTimeout,
+			state:             Disconnected,
 		}
 	})
 }

plugins/inputs/mqtt_consumer/mqtt_consumer_test.go

@@ -13,23 +13,16 @@ import (
 
 const (
 	testMsg    = "cpu_load_short,host=server01 value=23422.0 1422568543702900257\n"
-	testMsgNeg      = "cpu_load_short,host=server01 value=-23422.0 1422568543702900257\n"
-	testMsgGraphite = "cpu.load.short.graphite 23422 1454780029"
-	testMsgJSON     = "{\"a\": 5, \"b\": {\"c\": 6}}\n"
 	invalidMsg = "cpu_load_short,host=server01 1422568543702900257\n"
 )
 
-func newTestMQTTConsumer() (*MQTTConsumer, chan mqtt.Message) {
+func newTestMQTTConsumer() *MQTTConsumer {
-	in := make(chan mqtt.Message, 100)
 	n := &MQTTConsumer{
 		Topics:  []string{"telegraf"},
 		Servers: []string{"localhost:1883"},
-		in:        in,
-		done:      make(chan struct{}),
-		connected: true,
 	}
 
-	return n, in
+	return n
 }
 
 // Test that default client has random ID
@@ -79,31 +72,12 @@ func TestPersistentClientIDFail(t *testing.T) {
 }
 
 func TestRunParser(t *testing.T) {
-	n, in := newTestMQTTConsumer()
+	n := newTestMQTTConsumer()
 	acc := testutil.Accumulator{}
 	n.acc = &acc
-	defer close(n.done)
-
 	n.parser, _ = parsers.NewInfluxParser()
-	go n.receiver()
-	in <- mqttMsg(testMsgNeg)
-	acc.Wait(1)
 
-	if a := acc.NFields(); a != 1 {
+	n.recvMessage(nil, mqttMsg(testMsg))
-		t.Errorf("got %v, expected %v", a, 1)
-	}
-}
-
-func TestRunParserNegativeNumber(t *testing.T) {
-	n, in := newTestMQTTConsumer()
-	acc := testutil.Accumulator{}
-	n.acc = &acc
-	defer close(n.done)
-
-	n.parser, _ = parsers.NewInfluxParser()
-	go n.receiver()
-	in <- mqttMsg(testMsg)
-	acc.Wait(1)
 
 	if a := acc.NFields(); a != 1 {
 		t.Errorf("got %v, expected %v", a, 1)
@@ -112,84 +86,32 @@ func TestRunParserNegativeNumber(t *testing.T) {
 
 // Test that the parser ignores invalid messages
 func TestRunParserInvalidMsg(t *testing.T) {
-	n, in := newTestMQTTConsumer()
+	n := newTestMQTTConsumer()
 	acc := testutil.Accumulator{}
 	n.acc = &acc
-	defer close(n.done)
-
 	n.parser, _ = parsers.NewInfluxParser()
-	go n.receiver()
+
-	in <- mqttMsg(invalidMsg)
+	n.recvMessage(nil, mqttMsg(invalidMsg))
-	acc.WaitError(1)
 
 	if a := acc.NFields(); a != 0 {
 		t.Errorf("got %v, expected %v", a, 0)
 	}
-	assert.Contains(t, acc.Errors[0].Error(), "MQTT Parse Error")
+	assert.Len(t, acc.Errors, 1)
 }
 
 // Test that the parser parses line format messages into metrics
 func TestRunParserAndGather(t *testing.T) {
-	n, in := newTestMQTTConsumer()
+	n := newTestMQTTConsumer()
 	acc := testutil.Accumulator{}
 	n.acc = &acc
-
-	defer close(n.done)
-
 	n.parser, _ = parsers.NewInfluxParser()
-	go n.receiver()
-	in <- mqttMsg(testMsg)
-	acc.Wait(1)
 
-	n.Gather(&acc)
+	n.recvMessage(nil, mqttMsg(testMsg))
 
 	acc.AssertContainsFields(t, "cpu_load_short",
 		map[string]interface{}{"value": float64(23422)})
 }
 
-// Test that the parser parses graphite format messages into metrics
-func TestRunParserAndGatherGraphite(t *testing.T) {
-	n, in := newTestMQTTConsumer()
-	acc := testutil.Accumulator{}
-	n.acc = &acc
-	defer close(n.done)
-
-	n.parser, _ = parsers.NewGraphiteParser("_", []string{}, nil)
-	go n.receiver()
-	in <- mqttMsg(testMsgGraphite)
-
-	n.Gather(&acc)
-	acc.Wait(1)
-
-	acc.AssertContainsFields(t, "cpu_load_short_graphite",
-		map[string]interface{}{"value": float64(23422)})
-}
-
-// Test that the parser parses json format messages into metrics
-func TestRunParserAndGatherJSON(t *testing.T) {
-	n, in := newTestMQTTConsumer()
-	acc := testutil.Accumulator{}
-	n.acc = &acc
-	defer close(n.done)
-
-	n.parser, _ = parsers.NewParser(&parsers.Config{
-		DataFormat: "json",
-		MetricName: "nats_json_test",
-	})
-	go n.receiver()
-	in <- mqttMsg(testMsgJSON)
-
-	n.Gather(&acc)
-
-	acc.Wait(1)
-
-	acc.AssertContainsFields(t, "nats_json_test",
-		map[string]interface{}{
-			"a":   float64(5),
-			"b_c": float64(6),
-		})
-}
-
 func mqttMsg(val string) mqtt.Message {
 	return &message{
 		topic:   "telegraf/unit_test",