[NDM] fix bug on dedup on autodiscovery:

comp/core/autodiscovery/listeners/snmp.go

@@ -27,9 +27,7 @@ import (
 
 const cacheKeyPrefix = "snmp"
 
-var (
-	autodiscoveryStatusBySubnetVar = expvar.NewMap("snmpAutodiscovery")
-)
+var autodiscoveryStatusBySubnetVar = expvar.NewMap("snmpAutodiscovery")
 
 // AutodiscoveryStatus represents the status of the autodiscovery of a subnet we want to expose in the snmp status
 type AutodiscoveryStatus struct {
@@ -408,6 +406,11 @@ func (l *SNMPListener) checkDevices() {
 	discoveryTicker := time.NewTicker(time.Duration(l.config.DiscoveryInterval) * time.Second)
 	defer discoveryTicker.Stop()
 	for {
+		// Reset the device deduper counters at the start of each discovery interval
+		if l.deviceDeduper != nil {
+			l.deviceDeduper.ResetCounters()
+		}
+
 		for _, subnet := range subnets {
 			autodiscoveryStatusBySubnetVar.Set(GetSubnetVarKey(subnet.config.Network, subnet.index), &expvar.String{})
 		}

pkg/snmp/devicededuper/device_deduper.go

@@ -51,13 +51,15 @@ type DeviceDeduper interface {
 	MarkIPAsProcessed(ip string)
 	AddPendingDevice(device PendingDevice)
 	GetDedupedDevices() []PendingDevice
+	ResetCounters()
 }
 
 type deviceDeduperImpl struct {
 	sync.RWMutex
 	deviceInfos    []DeviceInfo
 	pendingDevices []PendingDevice
 	ipsCounter     map[string]*atomic.Uint32
+	config         snmp.ListenerConfig
 }
 
 // NewDeviceDeduper creates a new DeviceDeduper instance
@@ -66,9 +68,16 @@ func NewDeviceDeduper(config snmp.ListenerConfig) DeviceDeduper {
 		deviceInfos:    make([]DeviceInfo, 0),
 		pendingDevices: make([]PendingDevice, 0),
 		ipsCounter:     make(map[string]*atomic.Uint32),
+		config:         config,
 	}
 
-	for _, config := range config.Configs {
+	deduper.initializeCounters()
+
+	return deduper
+}
+
+func (d *deviceDeduperImpl) initializeCounters() {
+	for _, config := range d.config.Configs {
 		ipAddr, ipNet, err := net.ParseCIDR(config.Network)
 		if err != nil {
 			log.Errorf("Couldn't parse SNMP network: %s", err)
@@ -83,16 +92,14 @@ func NewDeviceDeduper(config snmp.ListenerConfig) DeviceDeduper {
 			}
 
 			ipStr := currentIP.String()
-			counter, exists := deduper.ipsCounter[ipStr]
+			counter, exists := d.ipsCounter[ipStr]
 			if !exists {
 				counter = &atomic.Uint32{}
-				deduper.ipsCounter[ipStr] = counter
+				d.ipsCounter[ipStr] = counter
 			}
 			counter.Add(uint32(len(config.Authentications)))
 		}
 	}
-
-	return deduper
 }
 
 func (d *deviceDeduperImpl) checkPreviousIPs(deviceIP string) bool {
@@ -179,6 +186,19 @@ func (d *deviceDeduperImpl) MarkIPAsProcessed(ip string) {
 	}
 }
 
+// ResetCounters resets the IP counters and device infos for a new discovery interval
+func (d *deviceDeduperImpl) ResetCounters() {
+	d.Lock()
+	defer d.Unlock()
+
+	for _, counter := range d.ipsCounter {
+		counter.Store(0)
+	}
+
+	d.initializeCounters()
+	d.deviceInfos = make([]DeviceInfo, 0)
+}
+
 func minimumIP(ipStr1, ipStr2 string) string {
 	ip1 := net.ParseIP(ipStr1)
 	ip2 := net.ParseIP(ipStr2)

pkg/snmp/devicededuper/device_deduper_test.go

@@ -6,11 +6,10 @@
 package devicededuper
 
 import (
+	"sync/atomic"
 	"testing"
 	"time"
 
-	"sync/atomic"
-
 	"github.com/DataDog/datadog-agent/pkg/snmp"
 	"github.com/stretchr/testify/assert"
 )
@@ -549,3 +548,62 @@ func TestNewDeviceDeduper(t *testing.T) {
 	}
 	assert.Equal(t, 4, count)
 }
+
+func TestDeviceDeduper_ResetCounters(t *testing.T) {
+	config := snmp.ListenerConfig{
+		Configs: []snmp.Config{
+			{
+				Network: "192.168.1.0/30",
+				Authentications: []snmp.Authentication{
+					{Community: "public"},
+					{Community: "private"},
+				},
+				IgnoredIPAddresses: map[string]bool{
+					"192.168.1.0": true,
+				},
+			},
+		},
+	}
+
+	deduper := NewDeviceDeduper(config)
+	deduperImpl, ok := deduper.(*deviceDeduperImpl)
+	assert.True(t, ok)
+
+	// Initially, all counters should be set to 2 (number of authentications)
+	count := deduperImpl.ipsCounter["192.168.1.1"].Load()
+	assert.Equal(t, uint32(2), count)
+	count = deduperImpl.ipsCounter["192.168.1.2"].Load()
+	assert.Equal(t, uint32(2), count)
+
+	// Process some IPs
+	deduper.MarkIPAsProcessed("192.168.1.1")
+	deduper.MarkIPAsProcessed("192.168.1.2")
+
+	count = deduperImpl.ipsCounter["192.168.1.1"].Load()
+	assert.Equal(t, uint32(1), count)
+	count = deduperImpl.ipsCounter["192.168.1.2"].Load()
+	assert.Equal(t, uint32(1), count)
+
+	// Add a discovered device
+	now := time.Now().UnixMilli()
+	deviceInfo := DeviceInfo{
+		Name:        "device1",
+		Description: "test device",
+		BootTimeMs:  now,
+		SysObjectID: "1.3.6.1.4.1.9.1.1",
+	}
+	deduperImpl.deviceInfos = append(deduperImpl.deviceInfos, deviceInfo)
+	assert.Len(t, deduperImpl.deviceInfos, 1)
+
+	// Reset counters
+	deduper.ResetCounters()
+
+	// Verify counters are reset to initial value
+	count = deduperImpl.ipsCounter["192.168.1.1"].Load()
+	assert.Equal(t, uint32(2), count)
+	count = deduperImpl.ipsCounter["192.168.1.2"].Load()
+	assert.Equal(t, uint32(2), count)
+
+	// Verify device infos are cleared
+	assert.Len(t, deduperImpl.deviceInfos, 0)
+}

releasenotes/notes/fix-snmp-autodiscovery-bug-c5885c5c2355f1ad.yaml

@@ -0,0 +1,11 @@
+# Each section from every release note are combined when the
+# CHANGELOG.rst is rendered. So the text needs to be worded so that
+# it does not depend on any information only available in another
+# section. This may mean repeating some details, but each section
+# must be readable independently of the other.
+#
+# Each section note must be formatted as reStructuredText.
+---
+fixes:
+  - |
+    Fix SNMP Autodiscovery bug where the Agent had to be restarted to take into account new devices discovered in a subnet.