Add support to parse JSON array. (#1965)

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
+	}
+}

plugins/parsers/json/parser_test.go

@@ -7,10 +7,12 @@ import (
 )
 
 const (
-	validJSON        = "{\"a\": 5, \"b\": {\"c\": 6}}"
-	validJSONNewline = "\n{\"d\": 7, \"b\": {\"d\": 8}}\n"
-	invalidJSON      = "I don't think this is JSON"
-	invalidJSON2     = "{\"a\": 5, \"b\": \"c\": 6}}"
+	validJSON              = "{\"a\": 5, \"b\": {\"c\": 6}}"
+	validJSONNewline       = "\n{\"d\": 7, \"b\": {\"d\": 8}}\n"
+	validJSONArray         = "[{\"a\": 5, \"b\": {\"c\": 6}}]"
+	validJSONArrayMultiple = "[{\"a\": 5, \"b\": {\"c\": 6}}, {\"a\": 7, \"b\": {\"c\": 8}}]"
+	invalidJSON            = "I don't think this is JSON"
+	invalidJSON2           = "{\"a\": 5, \"b\": \"c\": 6}}"
 )
 
 const validJSONTags = `
@@ -24,6 +26,27 @@ const validJSONTags = `
 }
 `
 
+const validJSONArrayTags = `
+[
+{
+    "a": 5,
+    "b": {
+        "c": 6
+    },
+    "mytag": "foo",
+    "othertag": "baz"
+},
+{
+    "a": 7,
+    "b": {
+        "c": 8
+    },
+    "mytag": "bar",
+    "othertag": "baz"
+}
+]
+`
+
 func TestParseValidJSON(t *testing.T) {
 	parser := JSONParser{
 		MetricName: "json_test",
@@ -282,3 +305,116 @@ func TestParseValidJSONDefaultTagsOverride(t *testing.T) {
 		"mytag": "foobar",
 	}, metrics[0].Tags())
 }
+
+// Test that json arrays can be parsed
+func TestParseValidJSONArray(t *testing.T) {
+	parser := JSONParser{
+		MetricName: "json_array_test",
+	}
+
+	// Most basic vanilla test
+	metrics, err := parser.Parse([]byte(validJSONArray))
+	assert.NoError(t, err)
+	assert.Len(t, metrics, 1)
+	assert.Equal(t, "json_array_test", metrics[0].Name())
+	assert.Equal(t, map[string]interface{}{
+		"a":   float64(5),
+		"b_c": float64(6),
+	}, metrics[0].Fields())
+	assert.Equal(t, map[string]string{}, metrics[0].Tags())
+
+	// Basic multiple datapoints
+	metrics, err = parser.Parse([]byte(validJSONArrayMultiple))
+	assert.NoError(t, err)
+	assert.Len(t, metrics, 2)
+	assert.Equal(t, "json_array_test", metrics[0].Name())
+	assert.Equal(t, map[string]interface{}{
+		"a":   float64(5),
+		"b_c": float64(6),
+	}, metrics[0].Fields())
+	assert.Equal(t, map[string]string{}, metrics[1].Tags())
+	assert.Equal(t, "json_array_test", metrics[1].Name())
+	assert.Equal(t, map[string]interface{}{
+		"a":   float64(7),
+		"b_c": float64(8),
+	}, metrics[1].Fields())
+	assert.Equal(t, map[string]string{}, metrics[1].Tags())
+}
+
+func TestParseArrayWithTagKeys(t *testing.T) {
+	// Test that strings not matching tag keys are ignored
+	parser := JSONParser{
+		MetricName: "json_array_test",
+		TagKeys:    []string{"wrongtagkey"},
+	}
+	metrics, err := parser.Parse([]byte(validJSONArrayTags))
+	assert.NoError(t, err)
+	assert.Len(t, metrics, 2)
+	assert.Equal(t, "json_array_test", metrics[0].Name())
+	assert.Equal(t, map[string]interface{}{
+		"a":   float64(5),
+		"b_c": float64(6),
+	}, metrics[0].Fields())
+	assert.Equal(t, map[string]string{}, metrics[0].Tags())
+
+	assert.Equal(t, "json_array_test", metrics[1].Name())
+	assert.Equal(t, map[string]interface{}{
+		"a":   float64(7),
+		"b_c": float64(8),
+	}, metrics[1].Fields())
+	assert.Equal(t, map[string]string{}, metrics[1].Tags())
+
+	// Test that single tag key is found and applied
+	parser = JSONParser{
+		MetricName: "json_array_test",
+		TagKeys:    []string{"mytag"},
+	}
+	metrics, err = parser.Parse([]byte(validJSONArrayTags))
+	assert.NoError(t, err)
+	assert.Len(t, metrics, 2)
+	assert.Equal(t, "json_array_test", metrics[0].Name())
+	assert.Equal(t, map[string]interface{}{
+		"a":   float64(5),
+		"b_c": float64(6),
+	}, metrics[0].Fields())
+	assert.Equal(t, map[string]string{
+		"mytag": "foo",
+	}, metrics[0].Tags())
+
+	assert.Equal(t, "json_array_test", metrics[1].Name())
+	assert.Equal(t, map[string]interface{}{
+		"a":   float64(7),
+		"b_c": float64(8),
+	}, metrics[1].Fields())
+	assert.Equal(t, map[string]string{
+		"mytag": "bar",
+	}, metrics[1].Tags())
+
+	// Test that both tag keys are found and applied
+	parser = JSONParser{
+		MetricName: "json_array_test",
+		TagKeys:    []string{"mytag", "othertag"},
+	}
+	metrics, err = parser.Parse([]byte(validJSONArrayTags))
+	assert.NoError(t, err)
+	assert.Len(t, metrics, 2)
+	assert.Equal(t, "json_array_test", metrics[0].Name())
+	assert.Equal(t, map[string]interface{}{
+		"a":   float64(5),
+		"b_c": float64(6),
+	}, metrics[0].Fields())
+	assert.Equal(t, map[string]string{
+		"mytag":    "foo",
+		"othertag": "baz",
+	}, metrics[0].Tags())
+
+	assert.Equal(t, "json_array_test", metrics[1].Name())
+	assert.Equal(t, map[string]interface{}{
+		"a":   float64(7),
+		"b_c": float64(8),
+	}, metrics[1].Fields())
+	assert.Equal(t, map[string]string{
+		"mytag":    "bar",
+		"othertag": "baz",
+	}, metrics[1].Tags())
+}