Add support to parse JSON array. (influxdata#1965)

Author: johnrengelman

CHANGELOG.md

@@ -30,6 +30,9 @@ documentation for configuring journald. There is also a [`logfile` config option
 available in 1.1, which will allow users to easily configure telegraf to
 continue sending logs to /var/log/telegraf/telegraf.log.
 
+- The JSON parser can now parse JSON data where the root object is an array.
+The parsing configuration is applied to each element of the array.
+
 ### Features
 
 - [#1726](https://github.com/influxdata/telegraf/issues/1726): Processor & Aggregator plugin support.

docs/DATA_FORMATS_INPUT.md

@@ -147,6 +147,62 @@ Your Telegraf metrics would get tagged with "my_tag_1"
 exec_mycollector,my_tag_1=foo a=5,b_c=6
 ```
 
+If the JSON data is an array, then each element of the array is parsed with the configured settings.
+Each resulting metric will be output with the same timestamp.
+
+For example, if the following configuration:
+
+```toml
+[[inputs.exec]]
+  ## Commands array
+  commands = ["/usr/bin/mycollector --foo=bar"]
+
+  ## measurement name suffix (for separating different commands)
+  name_suffix = "_mycollector"
+
+  ## Data format to consume.
+  ## Each data format has it's own unique set of configuration options, read
+  ## more about them here:
+  ## https://github.com/influxdata/telegraf/blob/master/docs/DATA_FORMATS_INPUT.md
+  data_format = "json"
+
+  ## List of tag names to extract from top-level of JSON server response
+  tag_keys = [
+    "my_tag_1",
+    "my_tag_2"
+  ]
+```
+
+with this JSON output from a command:
+
+```json
+[
+    {
+        "a": 5,
+        "b": {
+            "c": 6
+        },
+        "my_tag_1": "foo",
+        "my_tag_2": "baz"
+    },
+    {
+        "a": 7,
+        "b": {
+            "c": 8
+        },
+        "my_tag_1": "bar",
+        "my_tag_2": "baz"
+    }
+]
+```
+
+Your Telegraf metrics would get tagged with "my_tag_1" and "my_tag_2"
+
+```
+exec_mycollector,my_tag_1=foo,my_tag_2=baz a=5,b_c=6
+exec_mycollector,my_tag_1=bar,my_tag_2=baz a=7,b_c=8
+```
+
 # Value:
 
 The "value" data format translates single values into Telegraf metrics. This

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")
+				}
+			}
+		}
+	}
+}

plugins/parsers/json/parser.go

@@ -1,6 +1,7 @@
 package json
 
 import (
+	"bytes"
 	"encoding/json"
 	"fmt"
 	"strconv"
@@ -16,15 +17,22 @@ type JSONParser struct {
 	DefaultTags map[string]string
 }
 
-func (p *JSONParser) Parse(buf []byte) ([]telegraf.Metric, error) {
+func (p *JSONParser) parseArray(buf []byte) ([]telegraf.Metric, error) {
 	metrics := make([]telegraf.Metric, 0)
 
-	var jsonOut map[string]interface{}
+	var jsonOut []map[string]interface{}
 	err := json.Unmarshal(buf, &jsonOut)
 	if err != nil {
-		err = fmt.Errorf("unable to parse out as JSON, %s", err)
+		err = fmt.Errorf("unable to parse out as JSON Array, %s", err)
 		return nil, err
 	}
+	for _, item := range jsonOut {
+		metrics, err = p.parseObject(metrics, item)
+	}
+	return metrics, nil
+}
+
+func (p *JSONParser) parseObject(metrics []telegraf.Metric, jsonOut map[string]interface{}) ([]telegraf.Metric, error) {
 
 	tags := make(map[string]string)
 	for k, v := range p.DefaultTags {
@@ -44,7 +52,7 @@ func (p *JSONParser) Parse(buf []byte) ([]telegraf.Metric, error) {
 	}
 
 	f := JSONFlattener{}
-	err = f.FlattenJSON("", jsonOut)
+	err := f.FlattenJSON("", jsonOut)
 	if err != nil {
 		return nil, err
 	}
@@ -57,6 +65,21 @@ func (p *JSONParser) Parse(buf []byte) ([]telegraf.Metric, error) {
 	return append(metrics, metric), nil
 }
 
+func (p *JSONParser) Parse(buf []byte) ([]telegraf.Metric, error) {
+
+	if !isarray(buf) {
+		metrics := make([]telegraf.Metric, 0)
+		var jsonOut map[string]interface{}
+		err := json.Unmarshal(buf, &jsonOut)
+		if err != nil {
+			err = fmt.Errorf("unable to parse out as JSON, %s", err)
+			return nil, err
+		}
+		return p.parseObject(metrics, jsonOut)
+	}
+	return p.parseArray(buf)
+}
+
 func (p *JSONParser) ParseLine(line string) (telegraf.Metric, error) {
 	metrics, err := p.Parse([]byte(line + "\n"))
 
@@ -115,3 +138,13 @@ func (f *JSONFlattener) FlattenJSON(
 	}
 	return nil
 }
+
+func isarray(buf []byte) bool {
+	ia := bytes.IndexByte(buf, '[')
+	ib := bytes.IndexByte(buf, '{')
+	if ia > -1 && ia < ib {
+		return true
+	} else {
+		return false
+	}
+}