Hi Mathieu, I haven't explained well enough.
You are right, NM doesn't handle /etc/resolv.conf differently in Quantal. What has changed is the IP address that nm-dnsmasq listens on. This change *will* have an impact on some machines. A machine that has no file at /etc/resolv.conf, or an empty file there, falls back to the default "nameserver 127.0.0.1". (As resolv.conf(5), says "If no nameserver entries are present, the default is to use the name server on the local machine.") Such a machine has working name service with Precise NM, but loses name service as soon as Quantal NM is installed and restarted. Please note that I am not proposing that we do anything to /etc/resolv.conf. My proposal is that the administrator be *warned* that /etc/resolv.conf is missing. I also agree with the line of argument that administrators who customize their systems are responsible for adapting these customizations as necessary. Nevertheless I think we should do something in this case for two reasons. First, there were quite a few images derived from 12.04 which lacked /etc/resolv.conf. This was in part because at least two well known image-building tools failed to install the symlink on the generated image. So there are probably quite a few machines out there that lack /etc/resolv.conf, and in many cases the users won't have noticed any problem because name service worked on them for the reason described earlier. Second, because of broken images on one hand and inexperience with resolvconf on the other, some admins have undoubtedly deleted /etc/resolv.conf in order to "fix" name service; they will be not be happy if name service breaks again on the next upgrade. I have summarized these issues at https://bugs.launchpad.net/ubuntu/+source/resolvconf/+bug/1000244/comments/66 In order to confine warnings only to cases where we know that name service will break, we would issue the warning on upgrade to the new network-manager package only if we see that /etc/resolv.conf is missing and nm-dnsmasq is in use ("dns=dnsmasq" in /etc/NM/NM.conf). If /etc/resolv.conf is an empty file (as opposed to absent) then we should regard that as a deliberate configuration and issue no warning, since I haven't seen any reports of empty /etc/resolv.conf's arising from faulty images or tools. Less technically speaking, in the past few months I have corresponded with a number of Ubuntu users about resolvconf. What I repeatedly hear are complaints along the lines of: "you have changed the way UNIX has worked for decades" and "resolvconf isn't user-friendly" and "Ubuntu has fogotten the principle of K.I.S.S.". Obviously I don't share these feelings, but I do want to avoid making any more Ubuntu users feel this way if we can reasonably help it. And here is a case where I think we can easily avoid making some users angry with us. -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to network-manager in Ubuntu. https://bugs.launchpad.net/bugs/1060200 Title: Detect in the postinst that resolvconf is installed but /etc/resolv.conf is not a symlink to ../run/resolvconf/resolv.conf Status in “network-manager” package in Ubuntu: Triaged Bug description: I would like to start a discussion about a danger I see for 12.10. Resolvconf was introduced to Ubuntu core rather shortly before 12.04. Although resolvconf has been in Debian since 2003, popcon statistics suggest that this optional package is only installed on about 5% of Debian systems. Resolvconf proper hasn't been adopted by other major distros. Consequently resolvconf is not very well known yet. Consequently there are quite a few admins out there who don't know how to configure it. From the fact that there are so few resolvconf-related bug reports I think we can conclude that in the majority of cases the transition to resolvconf went fairly smoothly. The issues giving rise to bug #1000244 are, however, not negligible: there are images and tools out there that have set up Ubuntu 12.04 systems lacking the /etc/resolv.conf symlink. We can only imagine what has been done to fix up name resolving on those systems. I believe further that a significant number of admins out there have disabled resolvconf on their systems by deleting the /etc/resolv.conf symbolic link --- this was the quick way to get their system working without having to learn out how to configure resolvconf properly. The danger is that 12.10 will break a significant number of machines out there that lack symlink /etc/resolv.conf. Because of what was done to solve bug#959037, namely changing nm-dnsmasq's listen address to 127.0.1.1, any system that lacks the symlink and uses NetworkManager will have broken name service after upgrade. And it won't be obvious why name service is broken, either. Will we save ourselves and others a lot of trouble if we detect such cases and say in the network-manager postinst: "If resolvconf is installed and there is no symlink to ../run/resolvconf/resolv.conf at /etc/resolv.conf then put up a debconf warning telling the admin to address the issue, preferably by running 'dpkg-reconfigure resolvconf'"? To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/1060200/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp
