Archive for the ‘gentoo’ Category

Preserving your OpenAFS installation when switching IP addresses

March 30, 2008

About a week ago during spring break, I actually got OpenAFS running on an old computer that someone gave to me. There are two parts to the configuration, the client and the server. Getting the installation to properly run on the server was a challenge, but it worked. The client on the actual server was working, however when I tried to make it work with another separate computer, it totally crapped out. After a long waiting period in an IRC chatroom, it was noted that I had my /etc/hosts file totally wrong, and the file is not the same for the client and the server. For future reference, this is what the file needs to look like:                localhost

I was on a private network, so I just used ecks-net.priv for the network.ext string. However, whenever I used the vos listvldb command, it was showing me wrong output. Even when I fixed my /etc/hosts file it was showing the incorrect IP address. Apperently OpenAFS keeps a database of the server’s ip address taken from /etc/hosts upon initialization of the software, and keeps that in there no matter if you change your /etc/hosts file or IP address. If something like that happens, or for some reason the client registers the incorrect ip address, this is what you will need to do at the server:

vos syncvldb -server `hostname`  -verbose -localauth
vos syncserv -server `hostname`  -verbose -localauth
vos changeaddr localhost -remove -local
vos listaddr -nore
/etc/init.d/bos shutdown
cd /var/lib/openafs/DB
rm vldb.DB0 vldb.DBSYS1
cd /var/lib/openafs
rm sysid sysid.old
cd /var/log/openafs
rm *
/etc/init.d/openafs-server start
vos listvldb
vos syncvldb `hostname` -local- verbose
vos listvldb

Your vldb should now contain the correct hostname. What we did is we deleted the database file, then regenerated it back again. Here is a reference to the actual IRC log, you can track down the conversation by looking for the “noecksit” string. This is very useful when you change your static IP address and have to reconfigure OpenAFS with the new IP address.


gentoo-haskell ebuild

December 25, 2007

I just got done with another semester of college. It was tougher than usual since I had 6 classes. With the little time that I have had, I’ve been intently trying to learn Haskell, which is nothing like I have seen before, since it is purely functional, unlike all the other imperative languages I’m used to. It seems promising, but will probably take a while to fully grasp it. In trying to learn the languages, I’ve thought about making libmpd-haskell work with xmonad to play and stop music with a button. Midway through, someone changed something some feature in xmonad, and it stopped working anymore. Rather than try to fix this in a language I don’t know, I made a nice ebuild for gentoo instead.

my first ebuild

August 4, 2007

I have been using gentoo for quite a while and really love it, it gives you all the tools and more you would need. I especially love how easy it is to emerge stuff, all the dependencies are automatically installed without problems. I remember back in the days when I used Mandrake, I would have to search for hours trying to find which packages depended on which, and then manually install each one. It was really painful. Gentoo’s portage reminds me of FreeBSD’s ports that I used for half a year before switching. Gentoo, however has a much better package management system that FreeBSD, I think. Anyways, because I run a server at home, it is also behind a router, which assigns an ip address using dhcp everytime it boots up. The only way my computer can function as a server is if its DMZ ip address is set to the server. Therefore, I would have to manually update that ip address every time it is changed. Well, since computers are so good at automation, I decided to write a script in python that updates that the DMZ’s ip address every time it starts. Writing the script was relatively easy, because of python’s great urllib2 module, which can do almost anything involving http. The way Gentoo works is, it has a special folder inside /etc/init.d that have special scripts that are formatted just as if you are starting a service. For instance, to start apache, you would type:

$ /etc/init.d/apache2 start

This file also depends on a file in /etc/conf.d/ with the same name that supplies its global variables. Using ntp-client as an example, I was able to write up two files that call that script at start-up. Since this is a Gentoo-specific program, I also decided to write an ebuild, just for practice and to see what it looks like. Well, let me just say that my initial effort was fruitless. Thanks to the article on gentoo-wiki, I was able to with ease create an overlay in /usr/local/portage. When I looked at similar ebuilds, I realized that they have the syntax of a bash script, except they have custom names for installing and compiling packages. For instance, the make utility is called emake, and no use of tar is necessary, the key command is unpack. Well, initially I used dobin, which installs a file in /usr/bin, doconfd, installing in /etc/conf.d, and doinitd, installing in /etc/init.d. However, I realized soon that the files in conf.d and init.d actually have the same name, which they cannot have in the tar archive. I luckily found out they had newconfd and newinitd, which as a second argument specifies the destination file. Therefore, I could have two files with different names in the archive, but when they are installed, they will have the same name, just different paths. However, to my disappointment, when I tried to emerge the package, it said that they could not find the files in the current directory. Apparently, the current directory is known as $S (source) and the destination is $D. $S in turn translates into $WORKDIR/$P, whereas $WORKDIR is the the directory being worked on, and $P is just the name of the ebuild. In turn, through a regular cp command I realized that I needed $WORKDIR rather than $S as my current working directory. Changing into $WORKDIR worked quite well. Please check out my ebuild here.