Add support to parse JSON array. (#1965)

plugins/inputs/httpjson/README.md

@@ -37,6 +37,8 @@ You can also specify which keys from server response should be considered tags:
   ]
 ```
 
+If the JSON response is an array of objects, then each object will be parsed with the same configuration.
+
 You can also specify additional request parameters for the service:
 
 ```
@@ -150,3 +152,53 @@ httpjson_mycollector1_b_e,server='http://my.service.com/_stats' value=5
 httpjson_mycollector2_load,server='http://service.net/json/stats' value=100
 httpjson_mycollector2_users,server='http://service.net/json/stats' value=1335
 ```
+
+# Example 3, Multiple Metrics in Response:
+
+The response JSON can be treated as an array of data points that are all parsed with the same configuration.
+
+```
+[[inputs.httpjson]]
+  name = "mycollector"
+  servers = [
+    "http://my.service.com/_stats"
+  ]
+  # HTTP method to use (case-sensitive)
+  method = "GET"
+  tag_keys = ["service"]
+```
+
+which responds with the following JSON:
+
+```json
+[
+    {
+        "service": "service01",
+        "a": 0.5,
+        "b": {
+            "c": "some text",
+            "d": 0.1,
+            "e": 5
+        }
+    },
+    {
+        "service": "service02",
+        "a": 0.6,
+        "b": {
+            "c": "some text",
+            "d": 0.2,
+            "e": 6
+        }
+    }
+]
+```
+
+The collected metrics will be:
+```
+httpjson_mycollector_a,service='service01',server='http://my.service.com/_stats' value=0.5
+httpjson_mycollector_b_d,service='service01',server='http://my.service.com/_stats' value=0.1
+httpjson_mycollector_b_e,service='service01',server='http://my.service.com/_stats' value=5
+httpjson_mycollector_a,service='service02',server='http://my.service.com/_stats' value=0.6
+httpjson_mycollector_b_d,service='service02',server='http://my.service.com/_stats' value=0.2
+httpjson_mycollector_b_e,service='service02',server='http://my.service.com/_stats' value=6
+```

plugins/inputs/httpjson/httpjson_test.go

@@ -511,3 +511,52 @@ func TestHttpJson200Tags(t *testing.T) {
 		}
 	}
 }
+
+const validJSONArrayTags = `
+[
+	{
+		"value": 15,
+		"role": "master",
+		"build": "123"
+	},
+	{
+		"value": 17,
+		"role": "slave",
+		"build": "456"
+	}
+]`
+
+// Test that array data is collected correctly
+func TestHttpJsonArray200Tags(t *testing.T) {
+	httpjson := genMockHttpJson(validJSONArrayTags, 200)
+
+	for _, service := range httpjson {
+		if service.Name == "other_webapp" {
+			var acc testutil.Accumulator
+			err := service.Gather(&acc)
+			// Set responsetime
+			for _, p := range acc.Metrics {
+				p.Fields["response_time"] = 1.0
+			}
+			require.NoError(t, err)
+			assert.Equal(t, 8, acc.NFields())
+			assert.Equal(t, uint64(4), acc.NMetrics())
+
+			for _, m := range acc.Metrics {
+				if m.Tags["role"] == "master" {
+					assert.Equal(t, "123", m.Tags["build"])
+					assert.Equal(t, float64(15), m.Fields["value"])
+					assert.Equal(t, float64(1), m.Fields["response_time"])
+					assert.Equal(t, "httpjson_"+service.Name, m.Measurement)
+				} else if m.Tags["role"] == "slave" {
+					assert.Equal(t, "456", m.Tags["build"])
+					assert.Equal(t, float64(17), m.Fields["value"])
+					assert.Equal(t, float64(1), m.Fields["response_time"])
+					assert.Equal(t, "httpjson_"+service.Name, m.Measurement)
+				} else {
+					assert.FailNow(t, "unknown metric")
+				}
+			}
+		}
+	}
+}