lost functionality with jsonAta

[nicho2]

Relevant telegraf.conf

[[outputs.file]]
  ## Files to write to, "stdout" is a specially handled file.
  files = ["stdout"]

  ## Data format to output.
  ## Each data format has its own unique set of configuration options, read
  ## more about them here:
  ## https://github.com/influxdata/telegraf/blob/master/docs/DATA_FORMATS_OUTPUT.md
  data_format = "json"

	json_transformation = '''$merge([fields, {"tags": tags, "timestamp": $fromMillis(timestamp*1000)}])'''




# Read formatted metrics from one or more HTTP endpoints
[[inputs.http]]
  ## One or more URLs from which to read formatted metrics
  urls = [
	"https://api.weatherapi.com/v1/current.json?q=limoges&lang=fr&key=........&aqi=yes"
  ]


  ## Amount of time allowed to complete the HTTP request
  # timeout = "5s"

  ## List of success status codes
  # success_status_codes = [200]


  interval = "10s"
  
	# Exclude url and host items from tags
	tagexclude = ["url"]  
	
	
  ## Data format to consume.
  ## Each data format has its 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 = "influx"
  data_format = "json_v2"
	[[inputs.http.json_v2]]
			measurement_name_path = "current.condition"
        [[inputs.http.json_v2.object]]
			name_override = "currentWeatherCondition"
            path = "current.condition"
			excluded_keys = ["code"] # List of JSON keys (for a nested key, prepend the parent keys with underscores) that shouldn't be included in result

        [[inputs.http.json_v2.object]]
            path = "current.air_quality"

		[[inputs.http.json_v2.object]]
			path = "current"
			included_keys = ["is_day"]
			



# Process metrics using a Starlark script
[[processors.starlark]]
  ## The Starlark source can be set as a string in this configuration file, or
  ## by referencing a file containing the script.  Only one source or script
  ## should be set at once.
	#namepass = ["3ddlmlite_diag_neighbors"]
  ## Source of the Starlark script.
  source = '''
load("json.star", "json")
load("logging.star", "log")
	
def apply(metric):
	log.debug("debug: {}".format(metric.fields))
	if 'is_day' in metric.fields:
		metric.name = "is_day"
	elif "icon" in metric.fields:
		metric.name = "currentWeatherCondition"
	else:
		metric.name = "externalAirQuality"
	log.debug("debug_val: {}".format(metric))
	return metric
'''

Logs from Telegraf

time="2023-06-14T14:13:34+02:00" level=warning msg="The \"merge\" variable is not set. Defaulting to a blank string."
time="2023-06-14T14:13:34+02:00" level=warning msg="The \"fromMillis\" variable is not set. Defaulting to a blank string."
[{"icon":"//cdn.weatherapi.com/weather/64x64/day/113.png","text":"Ensoleillé"},{"tags":{"host":"FRL17040"},"timestamp":1686744825000}]
[{"co":176.89999389648438,"gb-defra-index":1,"no2":0.5,"o3":121.5999984741211,"pm10":6.099999904632568,"pm2_5":5.800000190734863,"so2":0.6000000238418579,"us-epa-index":1},{"tags":{"host":"FRL17040"},"timestamp":1686744825000}]
[{"is_day":1},{"tags":{"host":"FRL17040"},"timestamp":1686744825000}]
[{"icon":"//cdn.weatherapi.com/weather/64x64/day/113.png","text":"Ensoleillé"},{"tags":{"host":"FRL17040"},"timestamp":1686744833000}]
[{"co":176.89999389648438,"gb-defra-index":1,"no2":0.5,"o3":121.5999984741211,"pm10":6.099999904632568,"pm2_5":5.800000190734863,"so2":0.6000000238418579,"us-epa-index":1},{"tags":{"host":"FRL17040"},"timestamp":1686744833000}]
[{"is_day":1},{"tags":{"host":"FRL17040"},"timestamp":1686744833000}]

System info

Telegraf 1.27.0 (git: HEAD@dd48ee81)

Docker

No response

Steps to reproduce

1. run
2. without json_transformation data is:

{"fields":{"icon":"//cdn.weatherapi.com/weather/64x64/day/113.png","text":"Ensoleillé"},"name":"currentWeatherCondition","tags":{"host":"FRL17040"},"timestamp":1686745136}

try json transformation here:
https://try.jsonata.org/TuyDwaRsA
with jsonAta version 1.5.4

With Telegraf in version 1.26.2 the behaviour is correct. (it's regression!!)

Expected behavior

{
"icon": "//cdn.weatherapi.com/weather/64x64/day/113.png",
"text": "Ensoleillé",
"tags": {
"host": "FRL17040"
},
"timestamp": "2023-06-14T12:00:15.000Z"
}

Actual behavior

[{"icon":"//cdn.weatherapi.com/weather/64x64/day/113.png","text":"Ensoleillé"},{"tags":{"host":"FRL17040"},"timestamp":1686744833000}]

Additional info

No response

[powersj]

Going to track this in #13432 as a regression due to the env variable parsing.