Hi Willy, > Yes it is! They're typically used to drain old user sessions while > progressively taking a server off. Some also use them to let an > overloaded server cool down for a moment with no extra session. This > is completely unrelated to backup servers in fact, which have their > own weights and which can even be load balanced when all active servers > are dead.
This makes sense. I'm glad I know (now) I can use 0 weights to drain servers. > I suspect that it's more a property of the resolvers than the servers. > I mean, if you know that you're using your DNS servers this way, this > should really have the same meaning for all servers. So you shouldn't > have a per-server option to adjust this behavior but a per-resolvers > section. That's even better! And probably more easily implemented. I'll wait for Baptiste's response. Best, Luke — Luke Seelenbinder Stadia Maps | Founder stadiamaps.com > On 27 Feb 2020, at 16:11, Willy Tarreau <w...@1wt.eu> wrote: > > Hi Luke, > > On Thu, Feb 27, 2020 at 03:07:35PM +0100, Luke Seelenbinder wrote: >> Hello List, >> >> We use SRV records extensively (for internal service discovery, etc.). >> >> When the patch was integrated to support a 0 weighted SRV records, I thought >> that would simplify our setup, because at the time, I thought 0 weight meant >> "backup server" without a "backup" flag on the server. Unfortunately for our >> simplicity, that is not the case. A 0 weight means "will never be used unless >> explicitly chosen". >> >> That leads me to my questions: >> >> - Is that the intended behaviors of 0 weight servers: to not function as a >> backup if all other servers are down? > > Yes it is! They're typically used to drain old user sessions while > progressively taking a server off. Some also use them to let an > overloaded server cool down for a moment with no extra session. This > is completely unrelated to backup servers in fact, which have their > own weights and which can even be load balanced when all active servers > are dead. > >> - Would you (Willy?) accept a patch that used the Priority field of SRV >> records to determine backup/non-backup status? Or perhaps an additional >> server option to specify 0 weighted SRV records means "backup"? > > I suspect that it's more a property of the resolvers than the servers. > I mean, if you know that you're using your DNS servers this way, this > should really have the same meaning for all servers. So you shouldn't > have a per-server option to adjust this behavior but a per-resolvers > section. I'm personally not opposed to having more flexibility, and I > even find that it is a good idea. however I'm really not skilled at all > in the DNS area and Baptiste is the maintainer so I'm CCing him and > will let him decide. > > Cheers, > Willy
