error using json_query multiselect to reduce telegraf JSON data processing

[piyushsharma]

Relevant telegraf.conf:

[[inputs.tail]]
      files = ["/..../multiselect.log"]
      data_format = "json"
      tag_keys = ["@message","@fields.ouuid"]
      json_query = '{@timestamp,@message,@fields.duration,@fields.responseStatus}'
      json_time_key = "@timestamp"
      json_time_format = "2006-01-02T15:04:05Z07:00"

System info:

Telegraf 1.14.2
macOS Cataline 10.15.5

Steps to reproduce:

1. Sample Data:

{
  "@message": "Finished Request",
  "@timestamp": "2020-06-09T12:49:18.747Z",
  "@fields": {
    "ouuid": "nav",
    "event": "request",
    "method": "GET",
    "path": "xyz",
    "responseStatus": 200,
    "duration": 10.3845,
    "requestId": "ddd",
    "referer": "abc",
    "level": "info",
    "label": 100
  }
}

This type of JSON is present in each line of the file that I am processing.

2. Run telegraf --config telegraf.conf

Expected behavior:

See metrics being pushed to local influxdb.

Actual behavior:

I get the following error:

panic: runtime error: index out of range [0] with length 0

goroutine 28 [running]:
github.com/tidwall/gjson.Get(0xc0005000f0, 0xe6, 0xc000052ec1, 0xa, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
	/private/tmp/telegraf-20200429-52913-1ietmxf/telegraf-1.14.2/pkg/mod/github.com/tidwall/gjson@v1.3.0/gjson.go:1722 +0xe24
github.com/tidwall/gjson.Get(0xc0005000f0, 0xe6, 0xc000052ec0, 0x3d, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
	/private/tmp/telegraf-20200429-52913-1ietmxf/telegraf-1.14.2/pkg/mod/github.com/tidwall/gjson@v1.3.0/gjson.go:1734 +0x4ec
github.com/tidwall/gjson.getBytes(0xc0005000f0, 0xe6, 0xf0, 0xc000052ec0, 0x3d, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
	/private/tmp/telegraf-20200429-52913-1ietmxf/telegraf-1.14.2/pkg/mod/github.com/tidwall/gjson@v1.3.0/gjson_ngae.go:18 +0x10d
github.com/tidwall/gjson.GetBytes(...)
	/private/tmp/telegraf-20200429-52913-1ietmxf/telegraf-1.14.2/pkg/mod/github.com/tidwall/gjson@v1.3.0/gjson.go:1814
github.com/influxdata/telegraf/plugins/parsers/json.(*Parser).Parse(0xc000244320, 0xc0005000f0, 0xe6, 0xf0, 0xe6, 0xf0, 0xc0001f81e0, 0xe6, 0xc00048c080)
	/private/tmp/telegraf-20200429-52913-1ietmxf/telegraf-1.14.2/src/github.com/influxdata/telegraf/plugins/parsers/json/parser.go:189 +0x41b
github.com/influxdata/telegraf/plugins/inputs/tail.parseLine(0x68a8a80, 0xc000244320, 0xc0001f81e0, 0xe6, 0xc0001f8101, 0xe6, 0x0, 0x0, 0x0, 0x0)
	/private/tmp/telegraf-20200429-52913-1ietmxf/telegraf-1.14.2/src/github.com/influxdata/telegraf/plugins/inputs/tail/tail.go:206 +0x280
github.com/influxdata/telegraf/plugins/inputs/tail.(*Tail).receiver(0xc000120200, 0x68a8a80, 0xc000244320, 0xc0002e2bb0)
	/private/tmp/telegraf-20200429-52913-1ietmxf/telegraf-1.14.2/src/github.com/influxdata/telegraf/plugins/inputs/tail/tail.go:222 +0x25d
github.com/influxdata/telegraf/plugins/inputs/tail.(*Tail).tailNewFiles.func1(0xc000120200, 0x68a8a80, 0xc000244320, 0xc0002e2bb0)
	/private/tmp/telegraf-20200429-52913-1ietmxf/telegraf-1.14.2/src/github.com/influxdata/telegraf/plugins/inputs/tail/tail.go:177 +0x76
created by github.com/influxdata/telegraf/plugins/inputs/tail.(*Tail).tailNewFiles
	/private/tmp/telegraf-20200429-52913-1ietmxf/telegraf-1.14.2/src/github.com/influxdata/telegraf/plugins/inputs/tail/tail.go:175 +0x530

Additional info:

Some more context and discussion around this issue can be seen in the thread below:
#1363 (comment)