td-agent not picking up environment variables

[mattups]

I'm trying to make td-agent use and environment variable to get the user password for elasticsearch:

@type elasticsearch
host myelasticsearch
user fluentd
password "#{ENV['FLUENTD_PASSWORD']}"
port 9200

This snippet above is called by an @include directive of another file.

I tried to use export FLUENTD_PASSWORD=mypassord but when starting up td-agent it cannot authenticate to my elastcsearch.

td-agent version is: td-agent 4.1.1 fluentd 1.12.3 (b6e76c09d60ee866de6470f2bdd2551e7c8591d3)