Metricbeat/HTTP: Support array in http/json metricset

Currently (before this commit) the http/json metricset in Metricbeat
only can query information from http endpoints which expose
map[string]interface{}. For endpoints which expose an array on the
root level, the json metricset does not work.

A config option is added `response.isarray | bool`. If
someone configures array but a non array json object
is returned, an error is logged.

Event response is unified to []map[string]interface{} even
if the response is map[string]interface{}.

Signed-off-by: Jaipradeesh <jaipradeesh@gmail.com>

CHANGELOG.asciidoc

@@ -238,6 +238,7 @@ https://github.com/elastic/beats/compare/v6.0.0-beta2...master[Check the HEAD di
 - Refactor prometheus endpoint parsing to look similar to upstream prometheus {pull}6332[6332]
 - Update prometheus dependencies to latest {pull}6333[6333]
 - Making the http/json metricset GA. {pull}6471[6471]
+- Add support for array in http/json metricset. {pull}6480[6480]
 
 *Packetbeat*
 

metricbeat/docs/modules/http.asciidoc

@@ -35,6 +35,7 @@ metricbeat.modules:
   #method: "GET"
   #request.enabled: false
   #response.enabled: false
+  #json.is_array: false
   #dedot.enabled: false
 
 - module: http

metricbeat/metricbeat.reference.yml

@@ -222,6 +222,7 @@ metricbeat.modules:
   #method: "GET"
   #request.enabled: false
   #response.enabled: false
+  #json.is_array: false
   #dedot.enabled: false
 
 - module: http

metricbeat/module/http/_meta/config.yml

@@ -8,6 +8,7 @@
   #method: "GET"
   #request.enabled: false
   #response.enabled: false
+  #json.is_array: false
   #dedot.enabled: false
 
 - module: http

metricbeat/module/http/_meta/test/main.go

@@ -7,13 +7,20 @@ import (
 )
 
 func main() {
-	http.HandleFunc("/", serve)
+	http.HandleFunc("/jsonarr", serveJSONArr)
+	http.HandleFunc("/jsonobj", serveJSONObj)
+	http.HandleFunc("/", serveJSONObj)
+
 	err := http.ListenAndServe(":8080", nil)
 	if err != nil {
 		log.Fatal("ListenAndServe: ", err)
 	}
 }
 
-func serve(w http.ResponseWriter, r *http.Request) {
+func serveJSONArr(w http.ResponseWriter, r *http.Request) {
+	fmt.Fprint(w, `[{"hello1":"world1"}, {"hello2": "world2"}]`)
+}
+
+func serveJSONObj(w http.ResponseWriter, r *http.Request) {
 	fmt.Fprint(w, `{"hello":"world"}`)
 }

metricbeat/module/http/json/_meta/data.json

@@ -5,15 +5,14 @@
         "name": "host.example.com"
     },
     "http": {
-        "testnamespace": {
+        "json": {
             "hello": "world"
         }
     },
     "metricset": {
-        "host": "http:8080",
+        "host": "127.0.0.1:8080",
         "module": "http",
         "name": "json",
-        "namespace": "testnamespace",
         "rtt": 115
     }
 }

metricbeat/module/http/json/_meta/test/config.yml

@@ -13,6 +13,7 @@ metricbeat.modules:
   headers:
     Accept: application/json
   request.enabled: true
+  json.is_array: false
   response.enabled: true
 
 #================================ Outputs =====================================

metricbeat/module/http/json/json.go

@@ -49,6 +49,7 @@ type MetricSet struct {
 	body            string
 	requestEnabled  bool
 	responseEnabled bool
+	jsonIsArray     bool
 	deDotEnabled    bool
 }
 
@@ -63,12 +64,14 @@ func New(base mb.BaseMetricSet) (mb.MetricSet, error) {
 		Body            string `config:"body"`
 		RequestEnabled  bool   `config:"request.enabled"`
 		ResponseEnabled bool   `config:"response.enabled"`
+		JSONIsArray     bool   `config:"json.is_array"`
 		DeDotEnabled    bool   `config:"dedot.enabled"`
 	}{
 		Method:          "GET",
 		Body:            "",
 		RequestEnabled:  false,
 		ResponseEnabled: false,
+		JSONIsArray:     false,
 		DeDotEnabled:    false,
 	}
 
@@ -91,37 +94,18 @@ func New(base mb.BaseMetricSet) (mb.MetricSet, error) {
 		http:            http,
 		requestEnabled:  config.RequestEnabled,
 		responseEnabled: config.ResponseEnabled,
+		jsonIsArray:     config.JSONIsArray,
 		deDotEnabled:    config.DeDotEnabled,
 	}, nil
 }
 
-// Fetch methods implements the data gathering and data conversion to the right format
-// It returns the event which is then forward to the output. In case of an error, a
-// descriptive error must be returned.
-func (m *MetricSet) Fetch() (common.MapStr, error) {
-	response, err := m.http.FetchResponse()
-	if err != nil {
-		return nil, err
-	}
-	defer response.Body.Close()
-
-	var jsonBody map[string]interface{}
-	var event map[string]interface{}
-
-	body, err := ioutil.ReadAll(response.Body)
-	if err != nil {
-		return nil, err
-	}
-
-	err = json.Unmarshal(body, &jsonBody)
-	if err != nil {
-		return nil, err
-	}
+func (m *MetricSet) processBody(response *http.Response, jsonBody interface{}) common.MapStr {
+	var event common.MapStr
 
 	if m.deDotEnabled {
-		event = common.DeDotJSON(jsonBody).(map[string]interface{})
+		event = common.DeDotJSON(jsonBody).(common.MapStr)
 	} else {
-		event = jsonBody
+		event = jsonBody.(common.MapStr)
 	}
 
 	if m.requestEnabled {
@@ -148,7 +132,49 @@ func (m *MetricSet) Fetch() (common.MapStr, error) {
 	// Set dynamic namespace
 	event["_namespace"] = m.namespace
 
-	return event, nil
+	return event
+}
+
+// Fetch methods implements the data gathering and data conversion to the right format
+// It returns the event which is then forward to the output. In case of an error, a
+// descriptive error must be returned.
+func (m *MetricSet) Fetch() ([]common.MapStr, error) {
+	response, err := m.http.FetchResponse()
+	if err != nil {
+		return nil, err
+	}
+	defer response.Body.Close()
+
+	var jsonBody common.MapStr
+	var jsonBodyArr []common.MapStr
+	var events []common.MapStr
+
+	body, err := ioutil.ReadAll(response.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	if m.jsonIsArray {
+		err = json.Unmarshal(body, &jsonBodyArr)
+		if err != nil {
+			return nil, err
+		}
+
+		for _, obj := range jsonBodyArr {
+			event := m.processBody(response, obj)
+			events = append(events, event)
+		}
+	} else {
+		err = json.Unmarshal(body, &jsonBody)
+		if err != nil {
+			return nil, err
+		}
+
+		event := m.processBody(response, jsonBody)
+		events = append(events, event)
+	}
+
+	return events, nil
 }
 
 func (m *MetricSet) getHeaders(header http.Header) map[string]string {

metricbeat/module/http/json/json_integration_test.go

@@ -12,10 +12,10 @@ import (
 	mbtest "github.com/elastic/beats/metricbeat/mb/testing"
 )
 
-func TestFetch(t *testing.T) {
+func TestFetchObject(t *testing.T) {
 	compose.EnsureUp(t, "http")
 
-	f := mbtest.NewEventFetcher(t, getConfig())
+	f := mbtest.NewEventsFetcher(t, getConfig("object"))
 	event, err := f.Fetch()
 	if !assert.NoError(t, err) {
 		t.FailNow()
@@ -24,23 +24,47 @@ func TestFetch(t *testing.T) {
 	t.Logf("%s/%s event: %+v", f.Module().Name(), f.Name(), event)
 }
 
+func TestFetchArray(t *testing.T) {
+	compose.EnsureUp(t, "http")
+
+	f := mbtest.NewEventsFetcher(t, getConfig("array"))
+	event, err := f.Fetch()
+	if !assert.NoError(t, err) {
+		t.FailNow()
+	}
+
+	t.Logf("%s/%s event: %+v", f.Module().Name(), f.Name(), event)
+}
 func TestData(t *testing.T) {
 	compose.EnsureUp(t, "http")
 
-	f := mbtest.NewEventFetcher(t, getConfig())
-	err := mbtest.WriteEvent(f, t)
+	f := mbtest.NewEventsFetcher(t, getConfig("object"))
+	err := mbtest.WriteEvents(f, t)
 	if err != nil {
 		t.Fatal("write", err)
 	}
+
 }
 
-func getConfig() map[string]interface{} {
+func getConfig(jsonType string) map[string]interface{} {
+	var path string
+	var responseIsArray bool
+	switch jsonType {
+	case "object":
+		path = "/jsonobj"
+		responseIsArray = false
+	case "array":
+		path = "/jsonarr"
+		responseIsArray = true
+	}
+
 	return map[string]interface{}{
-		"module":     "http",
-		"metricsets": []string{"json"},
-		"hosts":      []string{getEnvHost() + ":" + getEnvPort()},
-		"path":       "/",
-		"namespace":  "testnamespace",
+		"module":        "http",
+		"metricsets":    []string{"json"},
+		"hosts":         []string{getEnvHost() + ":" + getEnvPort()},
+		"path":          path,
+		"namespace":     "testnamespace",
+		"json.is_array": responseIsArray,
 	}
 }
 

metricbeat/modules.d/http.yml.disabled

@@ -8,6 +8,7 @@
   #method: "GET"
   #request.enabled: false
   #response.enabled: false
+  #json.is_array: false
   #dedot.enabled: false
 
 - module: http