Add environment to hostname in environment variable

In the docker-compose config for one of my stacks I’ve got this:

SYSLOG_HOSTNAME: {{ index .Container.Config.Labels "" }}

and then in the logs this is shown with a hostname as ipsec-ipsec-router-4, for example.
Is it possible to add the environment name to the syslog_hostname value? So that it goes like development-ipsec-ipsec-router-4 for example?