I have the sneaking suspicion that Amazon's Elastic Load Balancer is based on HAProxy (and has been tracking the 1.5 series in development for some time). Nothing particularly evidentiary, but it's a glass slipper that fits very snugly.

I believe they use nginx. Traditionally ELB has been the most featureless LB's you'd ever encounter. That's in direct contrast with HAProxy. Truly a pain point with AWS IMO.

The AWS approach to things has been to launch things that are very basic and then add complexity only gradually and when they see steady demand for something. The flipside of that is that a) when they release something it, it's generally very solid, and b) what they support generally stays supported.

That does mean that there are a lot of people who want AWS to support some particular feature. But having seen how featuritis can really ruin a code base, I'm glad they're conservative; I want my infrastructure to be very reliable.

Mostly, HAProxy. In contrast, the AWS-clone Eucalyptus IaaS platform uses HAProxy for ELB functionality, mimicking AWS ELB functionality [1]

[1] https://github.com/eucalyptus/architecture/blob/master/featu...

ELB has features that nginx does not (health checks for one), and does not take advantage of many features that nginx does have. On the other hand, the feature set of HAProxy (1.5 branch, now "released") matches remarkably closely.

> ELB has features that nginx does not (health checks for one)

Check out Tengine, a Nginx fork made by Alibaba guys ;)

AWS is certainly on the list of "Who is using HAProxy" here: https://www.haproxy.com/

We heavily use Haproxy at Clever Cloud

It's not necessarily part of OpenStack, but you'll most likely find it in every openstack deployment out there.

We use it quite extensively for Rackspace's Cloudfiles (Openstack Swift). I discuss it a bit in this talk: https://www.youtube.com/watch?v=YxnFUQHIwNs

Linode's NodeBalancers are clearly HAProxy. I just wish they exposed more config options (such as the PROXY protocol - it's useless for SMTP without that).

Heh... I do feel like I'm promoting bud a way too much here, but it seems that it could be better suited for PaaS than HAProxy, mostly because of it's async SNI feature.

Basically, bud can load the certificates and private keys for a domain name on the fly, without putting all of them into configuration.