Support for flannel?

[bmorton]

CoreOS added a software network fabric for containers called flannel in version 554. Basically, it gives every Docker container an IP that is accessible from anywhere in the cluster.

For deployster, this means that we could stop doing the port mapping stuff and switch over to using these IPs directly. Open questions:

• Should we require flannel and use only this approach?
• Should we support both approaches and make this configurable?
• Should we just stick with what we've got?

If we go the flannel route, there's configuration information available. One thing we'd have to make sure and add to our service unit files are these directives:

Requires=flanneld.service
After=flanneld.service
Restart=always|on-failure

Other notes: We can get the Docker container's IP with: docker inspect --format '{{ .NetworkSettings.IPAddress }}' id