Turns out there is actually no black magic in systemd, they simply listen on 127.0.0.53 and forward dns requests there in resolv.conf.
Reason is the same as ours — to preserve compatibility with other applications. So we do the same in our code.
This PR also does two things:
- Adds `::1` into resolv.conf for IPv6 only resolvers.
- Drops `SO_REUSEPORT` from control options (it works without them).
Closes#8328
Signed-off-by: Dmitriy Matrenichev <dmitry.matrenichev@siderolabs.com>
This PR adds a new controller - `DNSServerController` that starts tcp and udp dns servers locally. Just like `EtcFileController` it monitors `ResolverStatusType` and updates the list of destinations from there.
Most of the caching logic is in our "lobotomized" "`CoreDNS` fork. We need this fork because default `CoreDNS` carries
full Caddy server and various other modules that we don't need in Talos. On our side we implement
random selection of the actual dns and request forwarding.
Closes#7693
Signed-off-by: Dmitriy Matrenichev <dmitry.matrenichev@siderolabs.com>
