override host on statsd metricset (#29103)

* override host on statsd metricset

* changelog

(cherry picked from commit 606a7d2)

CHANGELOG.next.asciidoc

@@ -375,6 +375,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Preliminary AIX support {pull}27954[27954]
 - Register additional name for `storage` metricset in the azure module. {pull}28447[28447]
 - Update reference to gosigar pacakge for filesystem windows fix. {pull}28909[28909]
+- Override `Host()` on statsd MetricSet {pull}29103[29103]
 
 *Packetbeat*
 

metricbeat/helper/server/udp/udp.go

@@ -71,6 +71,10 @@ func NewUdpServer(base mb.BaseMetricSet) (server.Server, error) {
 	}, nil
 }
 
+func (g *UdpServer) GetHost() string {
+	return g.udpaddr.String()
+}
+
 func (g *UdpServer) Start() error {
 	listener, err := net.ListenUDP("udp", g.udpaddr)
 	if err != nil {

x-pack/metricbeat/module/statsd/server/server.go

@@ -104,6 +104,12 @@ func New(base mb.BaseMetricSet) (mb.MetricSet, error) {
 	}, nil
 }
 
+// Host returns the hostname or other module specific value that identifies a
+// specific host or service instance from which to collect metrics.
+func (b *MetricSet) Host() string {
+	return b.server.(*udp.UdpServer).GetHost()
+}
+
 func buildMappings(config []StatsdMapping) (map[string]StatsdMapping, error) {
 	mappings := make(map[string]StatsdMapping, len(config))
 	replacer := strings.NewReplacer(".", `\.`, "<", "(?P<", ">", ">[^.]+)")