Json_v2 strange behavior

Telegraf
1

I’m building a telegraf config to parse JSON data from OpenWeatherMap API. I’m seeing unexpected behavior, where some fields are duplicated. This is a problem when writing to Prometheus because it will cause duplicate timestamp errors. Could someone please explain why the JSON parser works this way? Here’s an example telegraf config:

[[inputs.file]]
  files = ["./openweathermap.json"]
  data_format = "json_v2"
  [[inputs.file.json_v2]]
    [[inputs.file.json_v2.tag]]
      path = "coord.lon"
    [[inputs.file.json_v2.tag]]
      path = "coord.lat"

    [[inputs.file.json_v2.object]]
      path = "main"
    [[inputs.file.json_v2.object]]
      path = "wind"
    [[inputs.file.json_v2.field]]
      path = "visibility"

The output looks like this; the visibility field appears twice:

> file,lat=34.1355,lon=-116.0543 feels_like=299.75,humidity=28,pressure=1003,temp=300.56,temp_max=301.56,temp_min=297.02,visibility=10000 1718608445000000000
> file,lat=34.1355,lon=-116.0543 deg=307,gust=7.15,speed=3.58,visibility=10000 1718608445000000000

Example JSON:

{
    "coord": {
        "lon": -116.0543,
        "lat": 34.1355
    },
    "weather": [
        {
            "id": 800,
            "main": "Clear",
            "description": "clear sky",
            "icon": "01n"
        }
    ],
    "base": "stations",
    "main": {
        "temp": 300.56,
        "feels_like": 299.75,
        "temp_min": 297.02,
        "temp_max": 301.56,
        "pressure": 1003,
        "humidity": 28
    },
    "visibility": 10000,
    "wind": {
        "speed": 3.58,
        "deg": 307,
        "gust": 7.15
    },
    "clouds": {
        "all": 0
    },
    "dt": 1718605565,
    "sys": {
        "type": 2,
        "id": 2020992,
        "country": "US",
        "sunrise": 1718541141,
        "sunset": 1718593069
    },
    "timezone": -25200,
    "id": 5404198,
    "name": "Twentynine Palms",
    "cod": 200
}
2

As a workaround, I added each field separately, instead of using objects. That works fine, but it makes the config file more verbose.

3

Out of curiosity, is there missing data or a reason you have not used the existing OpenWeatermap input plugin?

4

Haha, nope! I did not know it existed. I was just using inputs.http