When the dnsmasq package is installed its postinst starts the dnsmasq
daemon via the initscript. Dnsmasq initially reads what is most probably
an empty file from /var/run/dnsmasq/resolv.conf and so initially can't
resolve names. (The file is probably empty because it is generated by
/etc/resolvconf/update.d/dnsmasq which is included in the dnsmasq
package.) Then the dnsmasq initscript tells resolvconf that dnsmasq is
listening at 127.0.0.1. In response to this, resolvconf runs the
aforementioned hook script /etc/resolvconf/update.d/dnsmasq which writes
a new /var/run/dnsmasq/resolv.conf containing information about other
nameservers. The dnsmasq binary notices that the latter file has changed
and re-reads it. Meanwhile resolvconf updates /etc/resolv.conf to
contain "nameserver 127.0.0.1" so that the resolver will talk to
dnsmasq.
It's this "meanwhile" that is the problem. Resolvconf may update
resolv.conf to point to dnsmasq before dnsmasq is ready to resolve names
on the basis of the information just written to
/var/run/dnsmasq/resolv.conf.
In other words, you're right. :)
I think that the postinst should be enhanced such that if
/etc/resolvconf/update.d/dnsmasq has appeared or changed on install or
upgrade then it (the postinst) does "resolvconf -u" before starting
dnsmasq. The postinst should refrain from doing the "resolvconf -u" if
IGNORE_RESOLVCONF is set in /etc/default/dnsmasq.
** Changed in: dnsmasq (Ubuntu)
Status: New => Confirmed
** Also affects: dnsmasq (Debian)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1247803
Title:
dnsmasq temporarily breaks DNS resolution when starting for the first
time
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