Django on EC2 and S3

[frederi...@gmail.com]

I plan to go very big with django and use EC2 from Amazon.
Right now, I have the basic situation.
http://media.djangobook.com/content/chapter21/scaling-1.png (linux
instance,media, postgres on the same virtual machine)

But I plan to go bigger ;-) just in case
http://media.djangobook.com/content/chapter21/scaling-5.png

If you know EC2, you know that the two IP (private/public) for an
instance are distributed dynamically (and everything is lost when the
instance terminates).

That's not a problem for the first tier with dyndns and a ddlcient.
But what is the point for the database server (postgres/pgpool) in
cluster mode.

That's is not the only thing I plan. I would also do dynamic launch of
EC2 instance when needed. How would I manage that in configuration
files without restarting any server ???

I've got already account with weoceo.weogeo.com and www.rightscale.com,
but I don't know yet if these image would solve my questions.

Frédéric

[Joseph Heck]

You've pretty well nailed "issues with hosting on EC2" on the head. Some companies (non-Django related) are doing it, and they're backing up their databases to S3 and maintain a permanent proxy on dedicated hardware external to EC2 (as opposed to dyndns).

To my knowedlge, there's not been much heavy focus on people attempting to scale up a database on EC2 itself, but quite a number of folks have made aggressive use of instances that just do caching (memcached). The services have, at least, been reputed to be reasonably stable. I'm not sure I'd make that choice - there isn't any SLA, nor is there likely to be any - but if you're up for a gamble, it isn't out of the question.

There is an API to control bringing up and taking down instances, but you'd be better off asking those kinds of questions of the forums that Amazon maintains for their API's and services. Start digging around at http://developer.amazonwebservices.com/connect/forumindex.jspa

My own investigation indicated that I could just as easily, and more cheaply, get the immediate scale I needed with virtual server hosting external to Amazon. You might even consider looking around at alternate VPS and see what makes sense for you.

-joe