Kapacitor template with optional string variables

Dear team,

I tried to set up an optional string variable but causes a configuration error.

var output_measurement_preffix = string : ‘9010’

The only example I found is related to a lambda datatype as follows:
var optional_var = lamba : TRUE

Thank you

var output_measurement_prefix = '9010'

is enough and already a string.


I didn’t explain properly. I am using a template with a json parameter with the values.
@Mert this case is a constant. I would like to be a variables from an input file and in case of missing the parameter set a default value.

Best regards