Fix for Support Jolokia agent in proxy mode (elastic#4421)

metricbeat/module/jolokia/jmx/_meta/docs.asciidoc

@@ -22,6 +22,10 @@ mapping:
       attributes:
         - attr: Uptime
           field: uptime
+      target:
+          url: "service:jmx:rmi:///jndi/rmi://targethost:9999/jmxrmi"
+          user: "jolokia"
+          password: "s!cr!t"
 ---
 
 In case the underlying attribute is an object (e.g. see HeapMemoryUsage attribute in java.lang:type=Memory) its

metricbeat/module/jolokia/jmx/config.go

@@ -5,13 +5,20 @@ import "encoding/json"
 type JMXMapping struct {
 	MBean      string
 	Attributes []Attribute
+	Target     Target
 }
 
 type Attribute struct {
 	Attr  string
 	Field string
 }
 
+type Target struct {
+	Url      string
+	User     string
+	Password string
+}
+
 // RequestBlock is used to build the request blocks of the following format:
 //
 // [
@@ -35,6 +42,13 @@ type RequestBlock struct {
 	Type      string   `json:"type"`
 	MBean     string   `json:"mbean"`
 	Attribute []string `json:"attribute"`
+	Target    TargetBlock `json:"target"`
+}
+
+type TargetBlock struct {
+	Url      string `json:"url"`
+	User     string `json:"user"`
+	Password string `json:"password"`
 }
 
 func buildRequestBodyAndMapping(mappings []JMXMapping) ([]byte, map[string]string, error) {
@@ -45,6 +59,11 @@ func buildRequestBodyAndMapping(mappings []JMXMapping) ([]byte, map[string]strin
 		rb := RequestBlock{
 			Type:  "read",
 			MBean: mapping.MBean,
+			Target: TargetBlock {
+				Url: mapping.Target.Url,
+				User: mapping.Target.User,
+				Password: mapping.Target.Password,
+			},
 		}
 
 		for _, attribute := range mapping.Attributes {