cmd/scollector: Update SNMP timeout from 5s to 30s and allow override (…

…#1900)

cmd/scollector/conf/conf.go

@@ -52,6 +52,9 @@ type Conf struct {
 	// UserAgentMessage is an optional message that is appended to the User Agent
 	UserAgentMessage string
 
+	// SNMPTimeout is the number of seconds to wait for SNMP responses (default 30)
+	SNMPTimeout int
+
 	HAProxy        []HAProxy
 	SNMP           []SNMP
 	MIBS           map[string]MIB

cmd/scollector/main.go

@@ -25,6 +25,7 @@ import (
 	"bosun.org/metadata"
 	"bosun.org/opentsdb"
 	"bosun.org/slog"
+	"bosun.org/snmp"
 	"bosun.org/util"
 	"github.com/BurntSushi/toml"
 	"github.com/facebookgo/httpcontrol"
@@ -123,6 +124,9 @@ func main() {
 	if conf.ColDir != "" {
 		collectors.InitPrograms(conf.ColDir)
 	}
+	if conf.SNMPTimeout > 0 {
+		snmp.Timeout = conf.SNMPTimeout
+	}
 	var err error
 	check := func(e error) {
 		if e != nil {

snmp/snmp.go

@@ -10,6 +10,9 @@ import (
 	"bosun.org/snmp/asn1"
 )
 
+//Timeout is the number of seconds to use for conn.SetReadDeadline
+var Timeout = 30
+
 // reserved binding values.
 var (
 	null           = asn1.RawValue{Class: 0, Tag: 5}
@@ -236,7 +239,7 @@ func (s *SNMP) do(req *request) (*response, error) {
 		return nil, err
 	}
 	buf = make([]byte, 10000, 10000)
-	if err := conn.SetReadDeadline(time.Now().Add(5 * time.Second)); err != nil {
+	if err := conn.SetReadDeadline(time.Now().Add(time.Duration(Timeout) * time.Second)); err != nil {
 		return nil, err
 	}
 	n, err := conn.Read(buf)