Add JSON support:

 - rpc extensions to support both XML and JSON requests and responses
 - net support for a Eureka connection using JSON or XML
 - net support for marshalling and unmarshalling of the apps, app and instance structs
 - custom unmarshallers and intermediate wrapper structs to deal with nasty Eureka JSON

marshal.go

@@ -0,0 +1,104 @@
+package fargo
+
+// MIT Licensed (see README.md) - Copyright (c) 2013 Hudl <@Hudl>
+
+import (
+	"encoding/json"
+	//"fmt"
+	"strconv"
+)
+
+// Temporary structs used for GetAppsResponse unmarshalling
+type getAppsResponseArray GetAppsResponse
+type getAppsResponseSingle struct {
+	Application   *Application `json:"application"`
+	AppsHashcode  string       `json:"apps__hashcode"`
+	VersionsDelta int          `json:"versions__delta"`
+}
+
+// UnmarshalJSON is a custom JSON unmarshaler for GetAppsResponse to deal with
+// sometimes non-wrapped Application arrays when there is only a single Application item.
+func (r *GetAppsResponse) UnmarshalJSON(b []byte) error {
+	//fmt.Printf("GetAppsResponse.UnmarshalJSON b:%s\n", string(b))
+	var err error
+
+	// Normal array case
+	var ra getAppsResponseArray
+	if err = json.Unmarshal(b, &ra); err == nil {
+		//fmt.Printf("GetAppsResponse.UnmarshalJSON ra:%+v\n", ra)
+		*r = GetAppsResponse(ra)
+		return nil
+	}
+	// Bogus non-wrapped case
+	var rs getAppsResponseSingle
+	if err = json.Unmarshal(b, &rs); err == nil {
+		//fmt.Printf("GetAppsResponse.UnmarshalJSON rs:%+v\n", rs)
+		r.Applications = make([]*Application, 1, 1)
+		r.Applications[0] = rs.Application
+		r.AppsHashcode = rs.AppsHashcode
+		r.VersionsDelta = rs.VersionsDelta
+		return nil
+	}
+	return err
+}
+
+// Temporary structs used for Application unmarshalling
+type applicationArray Application
+type applicationSingle struct {
+	Name     string    `json:"name"`
+	Instance *Instance `json:"instance"`
+}
+
+// UnmarshalJSON is a custom JSON unmarshaler for Application to deal with
+// sometimes non-wrapped Instance array when there is only a single Instance item.
+func (a *Application) UnmarshalJSON(b []byte) error {
+	//fmt.Printf("Application.UnmarshalJSON b:%s\n", string(b))
+	var err error
+
+	// Normal array case
+	var aa applicationArray
+	if err = json.Unmarshal(b, &aa); err == nil {
+		//fmt.Printf("Application.UnmarshalJSON aa:%+v\n", aa)
+		*a = Application(aa)
+		return nil
+	}
+
+	// Bogus non-wrapped case
+	var as applicationSingle
+	if err = json.Unmarshal(b, &as); err == nil {
+		//fmt.Printf("Application.UnmarshalJSON as:%+v\n", as)
+		a.Name = as.Name
+		a.Instances = make([]*Instance, 1, 1)
+		a.Instances[0] = as.Instance
+		return nil
+	}
+	return err
+}
+
+type instance Instance
+
+// UnmarshalJSON is a custom JSON unmarshaler for Instance to deal with the
+// different Port encodings between XML and JSON. Here we copy the values from the JSON
+// Port struct into the simple XML int field.
+func (i *Instance) UnmarshalJSON(b []byte) error {
+	var err error
+	var ii instance
+	if err = json.Unmarshal(b, &ii); err == nil {
+		//fmt.Printf("Instance.UnmarshalJSON ii:%+v\n", ii)
+		*i = Instance(ii)
+		i.Port, _ = strconv.Atoi(ii.PortJ.Number)
+		i.SecurePort, _ = strconv.Atoi(ii.SecurePortJ.Number)
+		//i.Port = ii.PortJ.Number
+		//i.SecurePort = ii.SecurePortJ.Number
+		return nil
+	}
+	return err
+}
+
+// UnmarshalJSON is a custom JSON unmarshaler for InstanceMetadata to handle squirreling away
+// the raw JSON for later parsing.
+func (i *InstanceMetadata) UnmarshalJSON(b []byte) error {
+	i.Raw = b
+	// TODO(cq) could actually parse Raw here, and in a parallel UnmarshalXML as well.
+	return nil
+}

metadata.go

@@ -3,6 +3,7 @@ package fargo
 // MIT Licensed (see README.md) - Copyright (c) 2013 Hudl <@Hudl>
 
 import (
+	"encoding/json"
 	"fmt"
 	"github.com/clbanning/x2j"
 )
@@ -12,27 +13,38 @@ func (a *Application) ParseAllMetadata() error {
 	for _, instance := range a.Instances {
 		err := instance.Metadata.parse()
 		if err != nil {
-			log.Error("Failed parsing metadata for Instance=%s of Application=%s: ", instance.HostName, a.Name, err.Error())
+			log.Error("Failed parsing metadata for Instance=%s of Application=%s: %s", instance.HostName, a.Name, err.Error())
 			return err
 		}
 	}
 	return nil
 }
 
 func (im *InstanceMetadata) parse() error {
-	// wrap in a BS xml tag so all metadata tags are pulled
 	if len(im.Raw) == 0 {
 		im.parsed = make(map[string]interface{})
 		log.Debug("len(Metadata)==0. Quitting parsing.")
 		return nil
 	}
-	fullDoc := append(append([]byte("<d>"), im.Raw...), []byte("</d>")...)
-	parsedDoc, err := x2j.ByteDocToMap(fullDoc, true)
-	if err != nil {
-		log.Error("Error unmarshalling: ", err.Error())
-		return fmt.Errorf("error unmarshalling: ", err.Error())
+	//log.Debug("InstanceMetadata.parse: %s", im.Raw)
+
+	if len(im.Raw) > 0 && im.Raw[0] == '{' {
+		// JSON
+		err := json.Unmarshal(im.Raw, &im.parsed)
+		if err != nil {
+			log.Error("Error unmarshalling: %s", err.Error())
+			return fmt.Errorf("error unmarshalling: %s", err.Error())
+		}
+	} else {
+		// XML: wrap in a BS xml tag so all metadata tags are pulled
+		fullDoc := append(append([]byte("<d>"), im.Raw...), []byte("</d>")...)
+		parsedDoc, err := x2j.ByteDocToMap(fullDoc, true)
+		if err != nil {
+			log.Error("Error unmarshalling: %s", err.Error())
+			return fmt.Errorf("error unmarshalling: %s", err.Error())
+		}
+		im.parsed = parsedDoc["d"].(map[string]interface{})
 	}
-	im.parsed = parsedDoc["d"].(map[string]interface{})
 	return nil
 }
 
@@ -44,7 +56,7 @@ func (im *InstanceMetadata) GetMap() map[string]interface{} {
 func (im *InstanceMetadata) getItem(key string) (interface{}, bool, error) {
 	err := im.parse()
 	if err != nil {
-		return "", false, fmt.Errorf("parsing error: ", err.Error())
+		return "", false, fmt.Errorf("parsing error: %s", err.Error())
 	}
 	val, present := im.parsed[key]
 	return val, present, nil