Set the service name of the database to the enviroment variable CF_FLUENT_DB
and start the container in your cloud foundry space.
Or you can configure the postgres manually by enviroment variables
fluent_host="localhost"
fluent_port=5432
fluent_database="dbname"
fluent_username="user"
fluent_password="secret"
cf add-network-policy <fluntd-service-name> --destination-app <your-app> --port 24224 --protocol tcp