[LRUG] Idempotency vs the cloud

[Tom Taylor]

On 17 Jul 2013, at 12:13, Tom Stuart <tom at codon.com> wrote:

> If things begin to move more in that direction, can we stop caring about idempotent configuration management, and can it therefore become drastically simpler?

There's a lot to like about this approach, but for most applications, that need to maintain state in memory and on disk, it feels like you'd be moving more of the individual machine state into the global state, and that feels like a more complex beast to manage, with more unknown unknowns.

As Paul mentioned, moving storage around has a lot of friction, but there's also things cached in RAM that need rebuilding, and so on.

I've always found that a good design rule in engineering is to reduce the number of things that move. For many services a single well specced dedicated server will result in better reliability over a number of years than a distributed system spread across a number of VMs (at the trade off of flexibility).

That said, these are good problems to overcome, and solving them is attractive, not least because as you approach the scale of Google, Amazon and friends you're pretty much forced to. But they also feel sufficiently complex that I'd rather avoid them for as long as possible.

I think there's definitely room for a Sinatra to Chef/Puppet's Rails, but as most of us know, it doesn't take much to wish we'd just started the project in Rails.

t.