[Metricbeat] allow empty region/zone config param for storage metrics…

…et (elastic#17624) (elastic#17643)

* allow empty region/zone config param for storage metricset

(cherry picked from commit a8ef199)

CHANGELOG.next.asciidoc

@@ -196,6 +196,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Metricbeat no longer needs to be started strictly after Logstash for `logstash-xpack` module to report correct data. {issue}17261[17261] {pull}17497[17497]
 - Add privileged option so as mb to access data dir in Openshift. {pull}17606[17606]
 - Fix "ID" event generator of Google Cloud module {issue}17160[17160] {pull}17608[17608]
+- Fix storage metricset to allow config without region/zone. {issue}17623[17623] {pull}17624[17624]
 
 *Packetbeat*
 

x-pack/metricbeat/module/googlecloud/stackdriver/metricset.go

@@ -148,6 +148,11 @@ func validatePeriodForGCP(d time.Duration) (err error) {
 }
 
 func (c *config) Validate() error {
+	// storage metricset does not require region or zone config parameter.
+	if c.ServiceName == "storage" {
+		return nil
+	}
+
 	if c.Region == "" && c.Zone == "" {
 		return errors.New("region and zone in Google Cloud config file cannot both be empty")
 	}