Recommended way for encrypted overlay network to allow inter containers traffic (possible RTFM)


My team is running a small (old) setup of LXD & containers comprised of 90+ LXD images running on 4+ physical servers, using vpncloud (L2) and a dedicated container running a DHCP + DNS server to provide internal IP addresses to the containers connecting to the overlay network.
All containers have 2 NICs, 1 to connect to the overlay network, the (optional) other if internet connectivity though the LXD bridge is needed.

The setup works but involves a lot of moving parts and components outside of the LXD ecosystem. 4+ years later is there a standard/recommended way to achieve the same setup? As LXD & associated technologies are evolving rapidly, there may be a more standard stack to support this inter container communication. In particular, use of OVN seems a suitable candidate but may fall short for encryption (and L2?).

Required features:

  • Containers should be able to reach each other using internal naming, regardless of the physical server they are hosted on
  • Dynamic “internal” IP address allocation through DHCP with internal DNS eg $HOSTNAME.internal is added to the DNS internal resolver as soon as $HOSTNAME is provided an IP address by the DHCP server
  • Traffic between servers (or containers) is encrypted
  • Containers are non visible from the internet by default, explicit exposure (eg through lxd proxy) required
  • ability to add new physical servers and have guest on those servers accessing the overlay network, preferably without having the declare the new physical server on each existing server) / auto discovery
  • (optional) IP address allocation remains the same if an image is moved from one physical server to another. Today this is achieve through MAC address migration along with the container.

I regularly check but fail to see if the various proposed setups would be a suitable replacement / upgrade. As mentioned what is in place somehow “works” even if it feels clunky.


I think OVN will be able to provide what you’ve described here.

With the exception of encrypted overlay tunnels, which isn’t something LXD currently configures in OVN.

I’ve not explored it yet, but it does look like this is possible to enable in OVN though: