I used to have a docker version (maybe 0.6.2->0.6.5) where ip of a specific container stayed the same upon restarts.

Now, with 0.6.6, the ip changes at each container restart, is it a feature or a regression ?

/cc @jpetazzo

CC from my email on docker dev :
We have had some recent threads about docker networking support and today Jamshid Afshar started another related thread with the same problematic users already have.

From my humble point of experimentations:
Today:

• At each restart containers ip change.
• Docker applies rules on the fly, and cannot have a way to reconfigure network mapping rules (PAT) on demand.

Those are big stoppers for other tools integration like shorewall which for example:

• Does not support PAT rules with hostname/dns inside
• Does not support custom named chains unless you write some perl. Personally, Perl is not my cup of tea.
• My solution as of now is to write some scripts to save/reload the docker conf, see http://www.shorewall.net/shorewall_extension_scripts.htm. Idea is to save docker chains and restore them at different stages of the shorewall starting process.
• In other words, without care if shorewall (re)starts after docker, it kills the docker networking.

A reliable and predictable ip (re)configuration system is a musthave feature i think.

• In an ideal world, we can have a way to statically assign ourselves the ip addresses of the containers.
• And more generally, in any case, we must have a way to tell docker to (re)configure its networking mappings & rules without restarting the whole docker daemon & containers (reapply the docker rules & postrouting stuff). This would prevent to write unreliable & prone to errors cruft in other tools to save/restore docker stuff.