On Tue, Aug 30, 2016 at 6:18 AM, Maciej Katafiasz < mkatafi...@purestorage.com> wrote:
> On 27 August 2016 at 14:32, Tim Düsterhus <t...@bastelstu.be> wrote: > > Hello > > > > I want to run HAProxy 1.6.8 with a backend server that may have multiple > > A records corresponding to different containers. > > > > During testing I noticed that HAProxy only tries to connect to the first > > A record returned, instead of cycling through the different IP addresses > > returned (effectively treating every IP as a different backend server, > > with independent health checks). In case of a timeout the whole backend > > is treated as DOWN as well, instead of trying the next IP address. > > > > The reason for this setup is that it would be easier for me to add and > > remove backend containers in DNS than generating a new HAProxy > > configuration and reloading HAProxy whenever something changes. > > Be aware though that DNS round-robin reduces the availability of the > entire setup, since there are no provisions in the protocol for the > eviction of dead nodes. So unless you're very sure there will never be > any in your DNS and also have the TTL set to some very low value, > multiple DNS records will defeat some of the care HAProxy takes to > ensure it only sends requests to backends that can service them. > > Cheers, > Maciej > > Hmmm, one would think though the backend health check and fail over should take care of this ... or maybe not??? Anyway, in case you use something like Consul which I mentioned before to provide the DNS records, then Consul itself will remove the failed node from the DNS record.
