[erlang-questions] Why Amazon EC2 isn't yet a platform for real web applications

Toby DiPasquale <>
Thu Jun 21 19:44:56 CEST 2007


On 6/21/07, Brad Anderson <> wrote:
> Joel Reymont wrote:
> > Suppose you _do_ use the instances as load balancers _and_ use HTTP
> > redirect.
> >
> > Won't there be a separate connection to the target instance of your
> > choice once the load balancer figures out what the instance is and tells
> > the web browser?
>
> It could potentially be set up that way if you had all public IP addresses.  I
> just confirmed at ?DAYJOB that we do not have public IP's and all the traffic
> flows through our load balancers and the servers pass a private IP back and forth.
>
> >
> > On Jun 21, 2007, at 2:59 PM, Toby DiPasquale wrote:
> >
> >> Each instance only gets a fixed bandwidth limit, so they can't
> >> effectively be used as load balancers for other instances above
> >> whatever is the limit for a single instance (I think its 250Mbit at
> >> this point).
>
> This is why I think EC2 is a bit broken.  They gotta be hearing this from the
> masses.  Hopefully they have a solution forthcoming.

There are multiple threads on the EC2 forum asking for/lamenting the
missing load balancing functionality. As far as I could tell, doing
the round robin DNS was basically the only way to get load distributed
across EC2 instances without hitting the per-instance bandwidth limit.
If anyone has any other ideas, I'd love to hear them.

> How does your 'A records with multiple IPs' work?  You're using your registrar
> as a load balancer?  I guess you don't have much of a chance to manage
> affinity, if you need it at all.

Yeah, I am. I'm using Nettica (*) because they were the only ones to
provide a SOAP API to update these records when I turn instances up
and down (others' APIs didn't have this particular functionality that
I had found). Its actually baked right into the startup/shutdown
scripts of the instance. You are right, as well: I have no real
opportunity to manage affinity doing this.

(*) http://www.nettica.com/

-- 
Toby DiPasquale



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