Metricbeat: Set guest as default user in RabbitMQ module

CHANGELOG.asciidoc

@@ -247,6 +247,7 @@ https://github.com/elastic/beats/compare/v6.2.3...master[Check the HEAD diff]
 - Add shard metricset to Elasticsearch module. {pull}7006[7006]
 - Add apiserver metricset to Kubernetes module. {pull}7059[7059]
 - Add maxmemory to redis info metricset. {pull}7127[7127]
+- Set guest as default user in RabbitMQ module. {pull}7107[7107]
 
 *Packetbeat*
 

metricbeat/mb/parse/url.go

@@ -14,10 +14,12 @@ import (
 // URLHostParserBuilder builds a tailored HostParser for used with host strings
 // that are URLs.
 type URLHostParserBuilder struct {
-	PathConfigKey string
-	DefaultPath   string
-	DefaultScheme string
-	QueryParams   string
+	PathConfigKey   string
+	DefaultPath     string
+	DefaultUsername string
+	DefaultPassword string
+	DefaultScheme   string
+	QueryParams     string
 }
 
 // Build returns a new HostParser function whose behavior is influenced by the
@@ -37,13 +39,17 @@ func (b URLHostParserBuilder) Build() mb.HostParser {
 			if !ok {
 				return mb.HostData{}, errors.Errorf("'username' config for module %v is not a string", module.Name())
 			}
+		} else {
+			user = b.DefaultUsername
 		}
 		t, ok = conf["password"]
 		if ok {
 			pass, ok = t.(string)
 			if !ok {
 				return mb.HostData{}, errors.Errorf("'password' config for module %v is not a string", module.Name())
 			}
+		} else {
+			pass = b.DefaultPassword
 		}
 		t, ok = conf[b.PathConfigKey]
 		if ok {

metricbeat/module/rabbitmq/url.go

@@ -21,7 +21,9 @@ const (
 var (
 	// HostParser parses host urls for RabbitMQ management plugin
 	HostParser = parse.URLHostParserBuilder{
-		DefaultScheme: defaultScheme,
-		PathConfigKey: pathConfigKey,
+		DefaultScheme:   defaultScheme,
+		PathConfigKey:   pathConfigKey,
+		DefaultUsername: "guest",
+		DefaultPassword: "guest",
 	}.Build()
 )