Introducing the Fan – simpler container networking

“Canonical just announced a new, free, and very cool way to provide thousands of IP addresses to each of your VMs on AWS. Check out the fan networking on Ubuntu wiki page to get started, or read Dustin’s excellent fan walkthrough. Carry on here for a simple description of this happy little dose of awesome.

Containers are transforming the way people think about virtual machines (LXD) and apps (Docker). They give us much better performance and much better density for virtualisation in LXD, and with Docker, they enable new ways to move applications between dev, test and production. These two aspects of containers – the whole machine container and the process container, are perfectly complementary. You can launch Docker process containers inside LXD machine containers very easily. LXD feels like KVM only faster, Docker feels like the core unit of a PAAS.

The density numbers are pretty staggering. It’s *normal* to run hundreds of containers on a laptop.

And that is what creates one of the real frustrations of the container generation, which is a shortage of easily accessible IP addresses.

It seems weird that in this era of virtual everything that a number is hard to come by. The restrictions are real, however, because AWS restricts artificially the number of IP addresses you can bind to an interface on your VM. You have to buy a bigger VM to get more IP addresses, even if you don’t need extra compute. Also, IPv6 is nowehre to be seen on the clouds, so addresses are more scarce than they need to be in the first place.

So the key problem is that you want to find a way to get tens or hundreds of IP addresses allocated to each VM…”

Introducing the Fan – simpler container networking