Presenting qtchooser

A few days ago we the Qt/KDE team uploaded a new tool in the Qt ecosystem: qtchooser.

This tool is a wrapper tool used to select between different Qt versions. Of course, the first and easiest example is choosing between Qt4 and Qt5. But it doesn't end there: it can also be used to select a user's build of Qt.

To experienced Debian users, at first sight, it might resemble Debian's alternatives system. But it goes much further than that, allowing users (not sysadmins) to decide their defaults, and even adding new ones, user-wide. All this can be done using different methods like command line arguments, environment variables and configuration files.

Apart from all that, this is the recommended upstream way of managing Qt, being picked up by several (if not all) distributions, so it can easily be supported by upstream in their documentation.

My Qt4 package in Debian does not uses qtchooser, do I need to change anything?

No, we have tried to make things as smooth as possible. Your Qt4 packages should be safe. There will be more info on this later.

Debian/Ubuntu packages caching and mobile workstations

Not so long ago I read Dmitrijs' blog post on how to configure apt-cacher-ng to advertise it's service using avahi. As I normally use my laptop in my home and at work, and both networks have apt-cacher-ng running, I decided to give it a try.

I have been administering apt-cacher-ng for three networks so far, and I really find it a useful tool. Then, thanks to the aforementioned blog post, I discovered squid-deb-proxy. I don't use squid, so it's not for my normal use case, but some people will surely find it interesting.

But I found it's client package to be really interesting. It will discover any service providing _apt_proxy._tcp through avahi and let apt use it. But then the package wasn't available in Debian. So, I contacted Michael Vogt to see if he was interested in putting at least the client in Debian's archive. He took the opportunity to upload the full squid-deb-proxy, so thanks a lot Michael :-)

I then filled a wishlist bug against apt-cacher-ng to provide the avahi configuration for publishing the service, which Eduard included in the last version of it. So thanks a lot Eduard too!

tl;dr

You know only need apt-cacher-ng >= 0.7.13-1 and avahi-daemon installed on your server and your mobile users just need squid-deb-proxy-client. Then the proxy autoconfiguration for apt will just work.

One again, thanks a lot to the respective maintainers for allowing this into Jessie :-)

Gotchas

Yes, there are still some rough edges. On one of the networks I'm behind a proxy. While configuring my machine to use apt-cacher-ng's service as a proxy trough apt.conf, apt-listbugs would just work. But now, using the service as discovered by squid-deb-proxy-client, apt-listbugs just times out. Maybe I need to fill some other bug yet...

Qt 4.8.4 in experimental.

Since a few days we have Qt 4.8.4 (4:4.8.4+dfsg-3) in some archs of the experimental Debian archive. This release allows Qt4 to coexist with Qt5 while avoiding FTBFSs of current Qt4 packages in the archive.

So if you maintain a Qt4 app and want to check how it works with 4.8.4, you should be ready to go.