fix(inputs.knx_listener): Reconnect after connection loss (#14959)

plugins/inputs/knx_listener/knx_listener.go

@@ -3,9 +3,11 @@ package knx_listener
 
 import (
 	_ "embed"
+	"errors"
 	"fmt"
 	"reflect"
 	"sync"
+	"sync/atomic"
 
 	"github.com/vapourismo/knx-go/knx"
 	"github.com/vapourismo/knx-go/knx/dpt"
@@ -43,22 +45,27 @@ type KNXListener struct {
 	gaTargetMap map[string]addressTarget
 	gaLogbook   map[string]bool
 
-	acc telegraf.Accumulator
-	wg  sync.WaitGroup
+	wg        sync.WaitGroup
+	connected atomic.Bool
 }
 
 func (*KNXListener) SampleConfig() string {
 	return sampleConfig
 }
 
-func (kl *KNXListener) Gather(_ telegraf.Accumulator) error {
+func (kl *KNXListener) Gather(acc telegraf.Accumulator) error {
+	if !kl.connected.Load() {
+		// We got disconnected for some reason, so try to reconnect in every
+		// gather cycle until we are reconnected
+		if err := kl.Start(acc); err != nil {
+			return fmt.Errorf("reconnecting to bus failed: %w", err)
+		}
+	}
+
 	return nil
 }
 
-func (kl *KNXListener) Start(acc telegraf.Accumulator) error {
-	// Store the accumulator for later use
-	kl.acc = acc
-
+func (kl *KNXListener) Init() error {
 	// Setup a logbook to track unknown GAs to avoid log-spamming
 	kl.gaLogbook = make(map[string]bool)
 
@@ -80,6 +87,10 @@ func (kl *KNXListener) Start(acc telegraf.Accumulator) error {
 		}
 	}
 
+	return nil
+}
+
+func (kl *KNXListener) Start(acc telegraf.Accumulator) error {
 	// Connect to the KNX-IP interface
 	kl.Log.Infof("Trying to connect to %q at %q", kl.ServiceType, kl.ServiceAddress)
 	switch kl.ServiceType {
@@ -112,12 +123,15 @@ func (kl *KNXListener) Start(acc telegraf.Accumulator) error {
 		return fmt.Errorf("invalid interface type: %s", kl.ServiceAddress)
 	}
 	kl.Log.Infof("Connected!")
+	kl.connected.Store(true)
 
 	// Listen to the KNX bus
 	kl.wg.Add(1)
 	go func() {
-		kl.wg.Done()
-		kl.listen()
+		defer kl.wg.Done()
+		kl.listen(acc)
+		kl.connected.Store(false)
+		acc.AddError(errors.New("disconnected from bus"))
 	}()
 
 	return nil
@@ -130,7 +144,7 @@ func (kl *KNXListener) Stop() {
 	}
 }
 
-func (kl *KNXListener) listen() {
+func (kl *KNXListener) listen(acc telegraf.Accumulator) {
 	for msg := range kl.client.Inbound() {
 		// Match GA to DataPointType and measurement name
 		ga := msg.Destination.String()
@@ -177,7 +191,7 @@ func (kl *KNXListener) listen() {
 			"unit":         target.datapoint.(dpt.DatapointMeta).Unit(),
 			"source":       msg.Source.String(),
 		}
-		kl.acc.AddFields(target.measurement, fields, tags)
+		acc.AddFields(target.measurement, fields, tags)
 	}
 }
 

plugins/inputs/knx_listener/knx_listener_test.go

@@ -36,13 +36,13 @@ func setValue(data dpt.DatapointValue, value interface{}) error {
 	return nil
 }
 
-type TestMessage struct {
+type message struct {
 	address string
 	dpt     string
 	value   interface{}
 }
 
-func ProduceKnxEvent(t *testing.T, address string, datapoint string, value interface{}) *knx.GroupEvent {
+func produceKnxEvent(t *testing.T, address string, datapoint string, value interface{}) *knx.GroupEvent {
 	addr, err := cemi.NewGroupAddrString(address)
 	require.NoError(t, err)
 
@@ -60,7 +60,7 @@ func ProduceKnxEvent(t *testing.T, address string, datapoint string, value inter
 
 func TestRegularReceives_DPT(t *testing.T) {
 	// Define the test-cases
-	var testcases = []TestMessage{
+	var testcases = []message{
 		{"1/0/1", "1.001", true},
 		{"1/0/2", "1.002", false},
 		{"1/0/3", "1.003", true},
@@ -101,6 +101,7 @@ func TestRegularReceives_DPT(t *testing.T) {
 		Measurements: measurements,
 		Log:          testutil.Logger{Name: "knx_listener"},
 	}
+	require.NoError(t, listener.Init())
 
 	// Setup the listener to test
 	err := listener.Start(acc)
@@ -111,7 +112,7 @@ func TestRegularReceives_DPT(t *testing.T) {
 
 	// Send the defined test data
 	for _, testcase := range testcases {
-		event := ProduceKnxEvent(t, testcase.address, testcase.dpt, testcase.value)
+		event := produceKnxEvent(t, testcase.address, testcase.dpt, testcase.value)
 		client.Send(*event)
 	}
 
@@ -147,6 +148,7 @@ func TestRegularReceives_MultipleMessages(t *testing.T) {
 		},
 		Log: testutil.Logger{Name: "knx_listener"},
 	}
+	require.NoError(t, listener.Init())
 
 	acc := &testutil.Accumulator{}
 
@@ -155,15 +157,15 @@ func TestRegularReceives_MultipleMessages(t *testing.T) {
 	require.NoError(t, err)
 	client := listener.client.(*KNXDummyInterface)
 
-	testMessages := []TestMessage{
+	testMessages := []message{
 		{"1/1/1", "1.001", true},
 		{"1/1/1", "1.001", false},
 		{"1/1/2", "1.001", false},
 		{"1/1/2", "1.001", true},
 	}
 
 	for _, testcase := range testMessages {
-		event := ProduceKnxEvent(t, testcase.address, testcase.dpt, testcase.value)
+		event := produceKnxEvent(t, testcase.address, testcase.dpt, testcase.value)
 		client.Send(*event)
 	}
 
@@ -190,3 +192,65 @@ func TestRegularReceives_MultipleMessages(t *testing.T) {
 	require.Truef(t, ok, "bool type expected, got '%T' with '%v' value instead", acc.Metrics[1].Fields["value"], acc.Metrics[1].Fields["value"])
 	require.False(t, v)
 }
+
+func TestReconnect(t *testing.T) {
+	listener := KNXListener{
+		ServiceType: "dummy",
+		Measurements: []Measurement{
+			{"temperature", "1.001", []string{"1/1/1"}},
+		},
+		Log: testutil.Logger{Name: "knx_listener"},
+	}
+	require.NoError(t, listener.Init())
+
+	var acc testutil.Accumulator
+
+	// Setup the listener to test
+	require.NoError(t, listener.Start(&acc))
+	defer listener.Stop()
+	client := listener.client.(*KNXDummyInterface)
+
+	testMessages := []message{
+		{"1/1/1", "1.001", true},
+		{"1/1/1", "1.001", false},
+		{"1/1/2", "1.001", false},
+		{"1/1/2", "1.001", true},
+	}
+
+	for _, testcase := range testMessages {
+		event := produceKnxEvent(t, testcase.address, testcase.dpt, testcase.value)
+		client.Send(*event)
+	}
+
+	// Give the accumulator some time to collect the data
+	require.Eventuallyf(t, func() bool {
+		return acc.NMetrics() >= 2
+	}, 3*time.Second, 100*time.Millisecond, "expected 2 metric but got %d", acc.NMetrics())
+	require.True(t, listener.connected.Load())
+
+	client.Close()
+
+	require.Eventually(t, func() bool {
+		return !listener.connected.Load()
+	}, 3*time.Second, 100*time.Millisecond, "no disconnect")
+	acc.Lock()
+	err := acc.FirstError()
+	acc.Unlock()
+	require.ErrorContains(t, err, "disconnected from bus")
+
+	require.NoError(t, listener.Gather(&acc))
+	require.Eventually(t, func() bool {
+		return listener.connected.Load()
+	}, 3*time.Second, 100*time.Millisecond, "no reconnect")
+	client = listener.client.(*KNXDummyInterface)
+
+	for _, testcase := range testMessages {
+		event := produceKnxEvent(t, testcase.address, testcase.dpt, testcase.value)
+		client.Send(*event)
+	}
+
+	// Give the accumulator some time to collect the data
+	require.Eventuallyf(t, func() bool {
+		return acc.NMetrics() >= 2
+	}, 3*time.Second, 100*time.Millisecond, "expected 2 metric but got %d", acc.NMetrics())
+}