Archive for July, 2009

Okay, so this is a long-awaited follow-up to my first post on the topic of  Debian Perl Packaging. Some of you might note I was pretty extreme in the first post, which is partially because people only really ever respond to extremes when they’re new to things. When you first begin programming, the advice you get is “hey, never use goto statements” — but as your progress in your ability and your understanding of how it works, what it’s actually doing in the compiler — then it might not be so bad after all. In fact, I hear the Linux kernel uses it extensively to provide Exceptions in C. The Wikipedia page on exception handling in various languages shows how to implement exceptions in C using setjmp/longjmp (which is essentially a goto statement). But I digress.

Back to the main point of this writeup. Previously I couldn’t really think of cases where packaging your own modules is really all that useful, especially when packaging them for Debian means that you benefit many communities — Debian, Ubuntu, and all of the distributions that are based on those.

During a discussion with Hans Dieter Piercey after his article providing a nice comparison between dh-make-perl and cpan2dist. (Aside: I feel like he was slightly biased toward cpan2dist in his writeup, but I’m myself biased toward dh-make-perl, so he might be right, even though I won’t admit it.)

I’m really glad for that article and the ensuing dialog, because it really got people talking about what they use Debian Perl packages for, and where it is useful to make your own.

Firstly, if you’ve got an application that depends on some Perl module that isn’t managed by Debian, but you need it yesterday, then you can either install that module via CPAN or roll your own Debian package. The idea here is to make and install the package so you can use it, but also file a Request For Package bug at the same time — see the reportbug command in Debian, or use LaunchPad if you’re on Ubuntu. This way, when the package is officially released and supported, you can move to that instead, and thus get the benefits of automatic upgrades of those packages.

Secondly, if you’ve got an application that depends on some internally-developed modules, then they probably wouldn’t exist on CPAN (some call this Perl code part of the DarkPAN), except in the rare case that a company open sources their work. But corporations will never open source all of their work, even if they consider the implications of providing some of it to the open source community, so at some point or another you’ll need to deal with internal packages. Previously, the best way to handle this was to construct your own CPAN local mirror, and have other machines install and upgrade from it — thus your internal code is easily distributed via the usual mechanism.

One of the advantages of using CPAN to distribute things is that it’s available on most platforms, builds things and runs tests automatically on many platforms. CPANPLUS will even let you remove packages, which was one of the main reasons I am so pro-Debian packages anyway. However, it does mean you’ll need to rebuild the package on other systems, which is prone to failures that cost time and money to track down and fix. CPAN and CPANPLUS are the Perl tradition of distributing packages.

If you are using an environment mostly with Debian systems, however, you may benefit from using a local Debian repository. This way, you only need to upgrade packages in your repository, and they’ll be automatically upgraded along with the rest of your operating system (you do run update and upgrade periodically right?). There is even the fantastic aptcron program to automate this, so there’s really no excuse not to automatically update.

In either case, creating a local package means you will be able to easily remove anything you no longer need via the normal package management tools. You can also distribute the binary packages between machines — though it sometimes depends on the platform (for modules that incorporate C or other platform-specific code that needs to be rebuilt). Generally, most Perl modules are Pure Perl, and thus you can compile and test it once, on one machine, and distribute it to other ones simply by installing the .deb package on other machines. You can copy packages to machines and use dpkg to install them, or better yet, create a local Debian mirror so it’s done automatically and via the usual mechanism (aptitude, etc.)

In conclusion: if you’re going to make your own Debian packages, do so with caution, and be aware of all the consequences (positive and negative) of what you’re doing. As always, a real understanding of everything is necessary.

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It’s been some time since I re-installed Debian over my Kubuntu install, so I thought I’d discuss some reasons why I changed back to Debian, what my experience was like, and some learning opportunities.

One reason I made the switch was because there was a utility newly packaged for Debian, Frama-C, which was not available in Kubuntu at the time. It also frustrated me that I was having various frustrations with the installation, not the least of which was an unreliable and quite crashy KDE Plasma.

When I reinstalled this time, I picked the normal install but told it to install a graphical environment, which gave me a GNOME desktop environment. I actually rather like it, the setup didn’t ask too many questions and everything was set up perfectly. There was some minor tweaking, but it was all done by the easily accessible System menu and all the applets therein.

Now, I wanted to be able to use the server both as a virtual machine and as a physical dual-boot. This wasn’t working properly with GRUB-2, so I had to stay with version 1.96, which works rather well. I even spent some time making a pretty splashimage for it, which looks rather nice, even if I don’t see it all that often.

If I boot into the Virtual Machine, all the hardware is detected properly, and there aren’t even complaints about the fact that a bunch of hardware disappeared — certainly very good news if you decide to do something like move your hard drive to a different machine. Likewise, if I boot into the desktop, everything works well there too.

One issue I came across during the installation was having to teach Network-Manager how to configure my network interfaces. In my VMware NAT setup, there is no DHCP server, so the IP address, subnet and gateway information needs to be statically defined. Luckily, Network-Manager was able to do this based on the MAC address of the adapter — inside my virtual machine, it had a VMware-assigned static one. Through this, Network-Manager had an easy way to determine how to configure my network, and it works beautifully for Ethernet and Wireless (when Debian is running as the main operating system) and also for VMware NAT (when inside the virtual machine container).

Anyway, I have now been developing quite happily inside a Debian + GNOME desktop environment. The system runs fine even within a constrained environment, though I miss KDE’s setup with sudo; with GNOME, the option seems to be to have the root password entered every time privilege escalation is necessary. I don’t like using a root password — on my server system I don’t use the root password at all, and do everything I need to do via sudo. It’s okay for me because I log into the server with a private key and have disabled SSH password authentication for security reasons.

One thing that is still weird for me is that my system currently shows a time of 01:53 even though it is 23:57 in my timezone. Presumably the few minutes of difference is because the virtual machine clock and my system hardware clock aren’t synchronized perfectly, but more than that, I think it’s an issue with the Date applet somehow. I haven’t looked into this because the thing is running inside a virtual machine, so it doesn’t bother me much.

I have looked high and low to see where to change the time zone, and to my knowledge the system knows that it’s in the America/Toronto time zone. The house picture next to Timmins (the city I am in right now, though it doesn’t matter since the timezone is the same) seems to indicate to me that it’s set to the appropriate time zone.

I think it’s due to VMware synchronizing the virtual machine clock with my host machine clock. Windows (my host operating system) stores the time in the local format, which I believe Linux thinks is UTC. Still, it doesn’t explain the weird display it’s got going.

Someone noted last time that I didn’t make direct mention of which programs are only offered on Windows and not on Linux/etc, and that do not have reasonable replacement on these systems. Kapil Hari Paranjape noted that I was sounding somewhat like a troll by simply saying that I don’t think Linux is yet ready to replace my environment. Here was my reply:

Far from a troll, I’d really like Debian and Ubuntu, but moreso Linux in general, to improve at the pace it has been doing so. It’s made great progress since the last time I tried it out on my desktop, but I have to acknowledge that there are lots of rough edges right now that should be worked out.

One of the advantages of huge proprietary development organizations like Microsoft is that they have tons of developers and can implement new features at a relatively quick pace, even if they’re half-assed. Developers’ pride in the FOSS community prevents this overly quick pace of development in favour of more secure, more stable platforms. Which is a good thing, I think. But nonetheless it results in a “slower” development pace.

The applications I’m complaining about are things like:
– SolidWorks (a CAD tool for designing parts and assemblies, used in manufacturing and mechanical engineering)
– SpectrumSoft Micro-Cap (a version of software similar to PSpice used by my school)
– AutoCAD (another CAD tool)

Luckily this is changing, but only for the large & most popular distributions:
– MathWorks MATLAB (runs on Linux and Solaris, etc.)
– Wolfram Mathematica (which has versions for Linux and MacOS X)
– FEKO (runs on Linux and Solaris among others)

Anyway, I still consider SolidWorks to be a rather big program not supported on Linux, which is a big issue for those working on Civil Engineering programs. There are most probably others which are very domain-specific that I don’t even know about.

There is a nice matrix comparing cross-platform capabilities of CAD software: http://en.wikipedia.org/wiki/Comparison_of_CAD_software

Oh, one final thought: perhaps that KDE Recommends: should be moved to a Suggests: instead, on account of its heavy dependencies, requiring mysql-server installed on desktop machines.. WTF!

Oh, and on another note, I re-installed Debian using the non-expert Auto Install and it installed Gnome rather flawlessly, much like installing Ubuntu, which was pretty nice. So kudos to those who have been working on the main installer; it seems as though the advanced ones really give you some rope to hang yourself with, though :-)

Oh, and k3ninho told me that there is an initiative from the Ubuntu community called “100 Paper Cuts” to help fix small bugs like those I was complaining about. I hope this leads to an improved user experience, and I’d really like to see some of those changes propagated both upstream to Debian and upstream to the KDE folk.

During my install of Kubuntu + KDE, I felt that plasma was crashing more than Windows Explorer — it felt like the days when I was running Windows ME, and the shell would crash, and the system would restart it. Repeatedly. It’s exactly what seemed to happen with plasma. I’m not sure if it was something I screwed up during configuration (presumably so), but KDE was far too complicated for me to try and debug. It might also have been a result of me running my system within a fairly constrained virtual machine environment – the system only gets 768MB of RAM and no access to the actual graphics processor unit (since it’s virtualized).

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