Comment 3 for bug 1183831

This is an interesting use case that we hadn't considered, but I'm not sure we're in a position to support it in the immediate future; the most significant issue is that it's a provider-specific constraint; and each of those comes with a cost: that, while it makes juju more immediately valuable to a small number of people, it makes juju less valuable to everyone long-term, because it's a clear failure to express the concepts important to the user in a portable way.

So, "ec2-zone" is much too specific, and even "availability-zone" still isn't quite good enough; but, maybe, the ideas of "risk diversification" and "network distance" might effectively express the high-level goals enabled by zones, but in a manner suitable for use across clouds. We have mid-term plans to address both of these, but I'm not sure how well they address your use case; if you can spare the time, I'd like to know a little bit more about what you're doing, in case we can still come up with some neat refinement that solves your problems.