fix(inputs.snmp): snmp UseUnconnectedUDPSocket when using udp (#10331)

internal/snmp/config.go

@@ -9,7 +9,8 @@ type ClientConfig struct {
 	Timeout config.Duration `toml:"timeout"`
 	Retries int             `toml:"retries"`
 	// Values: 1, 2, 3
-	Version uint8 `toml:"version"`
+	Version              uint8 `toml:"version"`
+	UnconnectedUDPSocket bool  `toml:"unconnected_udp_socket"`
 	// Path to mib files
 	Path []string `toml:"path"`
 	// Translator implementation

internal/snmp/wrapper.go

@@ -36,6 +36,8 @@ func NewWrapper(s ClientConfig) (GosnmpWrapper, error) {
 
 	gs.Retries = s.Retries
 
+	gs.UseUnconnectedUDPSocket = s.UnconnectedUDPSocket
+
 	switch s.Version {
 	case 3:
 		gs.Version = gosnmp.Version3

plugins/inputs/snmp/README.md

@@ -30,6 +30,12 @@ path onto the global path variable
   ## SNMP version; can be 1, 2, or 3.
   # version = 2
 
+  ## Unconnected UDP socket
+  ## When true, SNMP reponses are accepted from any address not just
+  ## the requested address. This can be useful when gathering from
+  ## redundant/failover systems.
+  # unconnected_udp_socket = false 
+
   ## Path to mib files
   ## Used by the gosmi translator.
   ## To add paths when translating with netsnmp, use the MIBDIRS environment variable
@@ -349,6 +355,10 @@ needed:
 sudo tcpdump -s 0 -i eth0 -w telegraf-snmp.pcap host 127.0.0.1 and port 161
 ```
 
+## Metrics
+
+The field and tags will depend on the table and fields configured.
+
 ## Example Output
 
 ```shell