[dns] resolution fails on linux if running avahi-daemon

Question

[dns] resolution fails on linux if running avahi-daemon

samschlegel opened this issue 5 years ago · comments

If running avahi on Linux, it seems that it takes priority over the cluster.local. stub. dig works fine as that bypasses mDNS. Disabling avahi fixes name resolution.

Dmitriy Kalinin · Answer 1 · Thu Aug 08 2019 07:25:04 GMT+0800 (China Standard Time)

i havent tried linux setup with avahi but was aware of its existence. i take it you are unblocked by disabling it? were you relying on it on your system, or was it just default install?

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Sam Schlegel · Answer 2 · Fri Aug 09 2019 05:37:24 GMT+0800 (China Standard Time)

I rely on it for printing and connecting to some servers on my LAN, so while disabling it unblocked running kwt, it's not a long term solution.

Dmitriy Kalinin · Answer 3 · Fri Aug 09 2019 06:08:12 GMT+0800 (China Standard Time)

i see.

looks like currently i only enable mdns on os x:

https://github.com/k14s/kwt/blob/01506ff961c116370c4c7ceed1f6067d9630df57/pkg/kwt/cmd/net/dns_flags.go#L32 which controls https://github.com/k14s/kwt/blob/01506ff961c116370c4c7ceed1f6067d9630df57/pkg/kwt/cmd/net/dns_factory.go#L45

can you try running kwt net start command with --dns-mdns=true flag while avahi is running?

Sam Schlegel · Answer 4 · Fri Aug 09 2019 06:31:49 GMT+0800 (China Standard Time)

Hmm. kwt picks up the mdns requests and answers about 20 times, but curl still errors due to not being able to resolve the host. avahi-resolve -n also times out.

Sam Schlegel · Answer 5 · Fri Aug 09 2019 06:38:07 GMT+0800 (China Standard Time)

I could debug with Wireshark or something later, but for now I just adjusted my /etc/nsswitch.conf to not include [NOTFOUND=return] after mdns_minimal in order for it to fall back to DNS. Might also try using the built-in mDNS in systemd-resolved

Olav Cleemann · Answer 6 · Tue Sep 03 2019 03:18:58 GMT+0800 (China Standard Time)

I fixed it by moving the "dns" flag before the "mdns" flag in the /etc/nsswitch.conf. My "hosts" entry in that file now looks like this:

hosts: files dns mdns4_minimal [NOTFOUND=return] myhostname

Robert Kielty · Answer 7 · Sun Nov 10 2019 17:42:54 GMT+0800 (China Standard Time)

@phluks Thanks for this, your solution works for me.
For passers-by, make sure that you have your hostname at the of the end line

@cppforlife thanks for bringing my attention to this issue in particular and thanks for the k14s in general. Brilliant work.