Does any module support the heathy check of the backend upstreams?

[Michael Shadle]

On Wed, Jun 10, 2009 at 2:45 PM, merlin corey<merlincorey at dc949.org> wrote:
> How often do you really expect servers to go up and down?  I think you
> are correct, though, HUP can take a bit of time/resources.  My point
> is, are you really having upstreams die constantly?  Seems like you
> would have much worse problems than what it takes to HUP at that
> point...

In an infrastructure with 10's or 100's of servers, in theory you
could have one going up and down anytime.

Look at Amazon's whitepaper about Dynamo or how Google addresses the
whole "commodity" issue. Things will go up and down at anytime, and
you should gracefully handle it. nginx is almost capable of gracefully
doing it (mid-transfer I don't think it would unless the client
re-issued the request with a range offset) but with the
try-next-upstream approach it gracefully handles that already...

I'm looking to have a solution in place which can scale and is "set it
and forget it" - a HUP may be a lot of work, especially if nginx is
being the frontend for so many connections/servers. I don't know. I
guess Igor/Maxim would be the most knowledgeable about what exactly a
HUP will do to all of that...