Openweathermap input uses 3h rain value instead of 1h

[lhanson]

Relevant telegraf.conf:

[[inputs.openweathermap]]
  app_id = "my openweathermap API token"
  city_id = "[5261457]"
  fetch = ["weather"]
  units = "imperial"
  interval = "10m"

System info:

Telegraf 1.12.4
Raspbian Linux, kenrel 4.19.66

Steps to reproduce:

It's raining at my location right now. Temperature, humidity, and other values are refreshed every 10m by the plugin. The sample plugin configuration says that API data is updated every 10 minutes, though the openweathermap site merely indicates "<2 hours".

A call to the API shows this:

$ curl --silent "http://api.openweathermap.org/data/2.5/weather?id=5261457&units=imperial&appid=$OPENWEATHERMAP_TOKEN" | jq '.rain' 
{
  "1h": 0.91
}

Because the plugin references the 3h value which isn't present at the moment in the API, my graphs do not show that it is currently raining.

Expected behavior:

I'd like my data points to reflect current rain values as much as possible.

Actual behavior:

Current rain values aren't shown as the API isn't returning a "3h" average.

[lhanson]

And now that it's been >3h since I last checked in, the openweathermap API is still only showing 1h, so it apparently has nothing to do with actual rain values. Nothing on the openweathermap site is indicative of why that might be (though the fact that I'm not currently giving them money might be a factor).

If the upstream source doesn't seem to be providing the 3h values, I suggest the plugin switch to 1h. If this makes sense and it's a change which would be merged, I'd be happy to submit the PR myself.

[lhanson]

This seems to be something of a known issue, though not predictable when calling the API, and the rain values in general seem to be a bit flaky judging from the OpenWeatherMap support forum. The plugin should probably be flexible enough to use 1h if present, otherwise fall back to 3h.