Connection limit is inconsistent

[Michael Johnson]

Our API and CLI show the connection limit as '-1' which gets translated to not specifying a connection limit in the HAProxy configuration. When there is no connection limit specified in the HAProxy configuration it defaults to 2000 [1].
We are incorrectly documenting -1 as infinite in the documentation.

I think we should make the default 2000 and use that as the default instead of -1. There really isn't an "infinite" setting for HAProxy and setting it to 2000 means it is much less likely that the user will exhaust the amphora memory and cause the amphora to fail/failover.

[1] http://cbonte.github.io/haproxy-dconv/1.5/configuration.html#4.2-maxconn

[Stephen Balukoff (sbalukoff)]

That's correct. I don't think there's a way to tell haproxy to have "unlimited" connections, since it defaults to that value so it can set its open files limits properly on start-up. So yes, since haproxy is our default, it seems to make sense to me for this to default to 2000.

Note, in our testing, we could get to just shy of 10k connections on the default amphora image with default memory before the haproxy process on the amphora crashed. So, if we wanted, we could potentially set it a little higher than 2000. However, 2000 is probably a good place to start: Except for applications that have a LOT of long-lived connections, it's hard to even get to that 2000 limit for even high-volume sites.

[Dustin Lundquist (dlundquist)]

Where do we document a connection limit of -1 as being unlimited? I think it is an undefined connection limit, rather than an unlimited connection limit. I agree it is questionable to include either an undefined or unlimited connnection limit, a reasonable default would be a good idea. In choosing a default value, we should consider the future flavor framework and choose a default small enough to be accommodated in the smallest expected flavor.

[Michael Johnson (johnsom)]

It is listed as "unlimited' in the API docs:
http://developer.openstack.org/api-ref/networking/v2/?expanded=create-listener-detail

I have been reviewing our API reference for the merge and that is what caught my eye...

[Gregory Thiemonge (gthiemonge)]

Abandoned after re-enabling the Octavia launchpad.