3 ms·

I've been exploring DNS PTR/SRV records for seamless service discovery regardless of whether you have access to an authoritative DNS server configured for a giv

by dcow 9y ago

I've been exploring DNS PTR/SRV records for seamless service discovery regardless of whether you have access to an authoritative DNS server configured for a given local domain or not (so things simply devolve to whether or not use use multicast or unicast to resolve SRV records). Basically DNS-SD. The idea of using SRV records in general seems foreign even in the ops realm. It's awesome to see HAProxy beginning to familiarize people with the concept of SRV records.

jlgaddis 9y ago
> The idea of using SRV records in general seems foreign even in the ops realm. I'm not suggesting you use it but (as for how it works in general) look into how Microsoft's Active Directory works. They've had the "service discovery" problem figured out for going on two decades, including preferences for "closer" servers, weighting, and so on. I'm no MS fan by any means but AD is one MS product that really is awesome.
- snuxoll 9y ago
  And how does MS do it? SRV records, that’s right.
  - jlgaddis 9y ago
    Yeah, exactly. That's why I suggested he look into how it works (since "the idea ... seems foreign" to him). I didn't mean to suggest that they had some revolutionary new unique way of handling service discovery or even that they were the first. I think maybe you misinterpreted or misunderstood my intentions.
    - snuxoll 9y ago
      It’s all good, I got what you meant :) LDAP and Kerberos of all implementation are probably the most common use case for SRV records, most people probably don’t even know it. Real shame, in many ways I wish A/AAAA records weren’t even a thing for the vast majority of services (HTTP, I’m looking at you!)
empath75 9y ago
Consul supports this out of the box.
- bedis9 9y ago
  And HAProxy supports Consul out of the box thanks to this new feature :)
inopinatus 9y ago
I would love to see HTTP adopt SRV as well. Sadly the browser vendors think they're important enough that they can squat the address record all for themselves.
- tepmoc 9y ago
  Last argument I heard in chrome bugtracker it was - doing additional dns lookup slowdown user experience, which is why they abandoned idea adding it https://bugs.chromium.org/p/chromium/issues/detail?id=22423 https://bugs.chromium.org/p/chromium/issues/detail?id=22423
  - inopinatus 9y ago
    That is what we call in Australia a "furphy". SRV records do not intrinsically require an additional lookup or round trip. Poor zone configurations may fare less well. But that is true of all poor DNS configuration. For sites that care about resolution speed, they already optimise as necessary, and they would for SRV as well. Browsers do not own the A record and should never have been using it in the first place, so to continue squatting them and invent specious reasons for doing so is simple arrogance and assertion of unwarranted privilege. Instead we have the multiple warts and misbehaviours of misusing the DNS for URL endpoint resolution.

by dcow 9y ago

jlgaddis 9y ago

> The idea of using SRV records in general seems foreign even in the ops realm. I'm not suggesting you use it but (as for how it works in general) look into how Microsoft's Active Directory works. They've had the "service discovery" problem figured out for going on two decades, including preferences for "closer" servers, weighting, and so on. I'm no MS fan by any means but AD is one MS product that really is awesome.

snuxoll 9y ago
And how does MS do it? SRV records, that’s right.
- jlgaddis 9y ago
  Yeah, exactly. That's why I suggested he look into how it works (since "the idea ... seems foreign" to him). I didn't mean to suggest that they had some revolutionary new unique way of handling service discovery or even that they were the first. I think maybe you misinterpreted or misunderstood my intentions.
  - snuxoll 9y ago
    It’s all good, I got what you meant :) LDAP and Kerberos of all implementation are probably the most common use case for SRV records, most people probably don’t even know it. Real shame, in many ways I wish A/AAAA records weren’t even a thing for the vast majority of services (HTTP, I’m looking at you!)

empath75 9y ago

Consul supports this out of the box.

bedis9 9y ago
And HAProxy supports Consul out of the box thanks to this new feature :)

inopinatus 9y ago

I would love to see HTTP adopt SRV as well. Sadly the browser vendors think they're important enough that they can squat the address record all for themselves.

tepmoc 9y ago
Last argument I heard in chrome bugtracker it was - doing additional dns lookup slowdown user experience, which is why they abandoned idea adding it https://bugs.chromium.org/p/chromium/issues/detail?id=22423 https://bugs.chromium.org/p/chromium/issues/detail?id=22423
- inopinatus 9y ago
  That is what we call in Australia a "furphy". SRV records do not intrinsically require an additional lookup or round trip. Poor zone configurations may fare less well. But that is true of all poor DNS configuration. For sites that care about resolution speed, they already optimise as necessary, and they would for SRV as well. Browsers do not own the A record and should never have been using it in the first place, so to continue squatting them and invent specious reasons for doing so is simple arrogance and assertion of unwarranted privilege. Instead we have the multiple warts and misbehaviours of misusing the DNS for URL endpoint resolution.