Question: I'm using docker-compose for managing containers.

How to I turn off iptables (set --iptables=false for docker) when starting via docker-compose up?

Answer: 
The `--iptables` option only applies to the Docker daemon; it's not a per-container option. The corollary is that this isn't something you could ever set from your `docker-compose.yaml` file.

You would need to modify the options passed to the Docker daemon; on Red Hat systems and derivatives this means you would modify `/etc/sysconfig/docker` and updte the `OPTIONS=` line (and restart Docker). There will be a similar process for other distributions.
Could check out saltstack if you're looking for this level of automation. They have a dockerng state which allows you to specify options.

<https://docs.saltstack.com/en/latest/ref/states/all/salt.states.dockerng.html>