How to echo variable env in telegraf [[input.exec]] - bash

Question

I have a variable env and I want to get it in telegraf. I use [[inputs.exec]]
My code:
[[inputs.exec]]
commands = ["echo $val_env"]
data_format = "value"
data_type = "string"
name_override = "value_A"
But I can't get this value $val_env. I also test another way such as [echo "${val_env}"] or ["$val_env"], ... but as same.
How I can get value variable env in commands [[input.exec]] telegraf.

Answer 1

The variable val_env has to be exported to the environment that is running telegraf.
Here's an example, with most of the noise removed for brevity, and I've added to my config exactly what you described:
$ grep '^\[\[inputs.exec' -A4 /etc/telegraf/telegraf.conf
[[inputs.exec]]
commands = ["echo $val_env"]
data_format = "value"
data_type = "string"
name_override = "value_A"
$ export val_env='Tai Do'
$ telegraf
2022-12-22T11:51:31Z I! Using config file: /etc/telegraf/telegraf.conf
2022-12-22T11:51:31Z I! Starting Telegraf 1.25.0
2022-12-22T11:51:31Z I! Available plugins: 227 inputs, 9 aggregators, 26 processors, 21 parsers, 57 outputs, 2 secret-stores
2022-12-22T11:51:31Z I! Loaded inputs: cpu disk diskio exec kernel mem processes swap system
2022-12-22T11:51:31Z I! Loaded aggregators:
2022-12-22T11:51:31Z I! Loaded processors:
2022-12-22T11:51:31Z I! Loaded secretstores:
2022-12-22T11:51:31Z I! Loaded outputs: exec file
...
value_A,host=***,user=root value="Tai Do" 1671709900000000000