Multiple mysql engines on the same server

Someone asked me for a howto on setting up multiple mysql engines on the same linux server. There are many articles on the topic, but none provides an ready-to-use set of files which one can simply grab and go.

Thus I created multiple_mysql.tar.gz file that includes all files to run four mysql engines. The configuration assumes per-database directories /opt/db-330[4567] with bin_log, mysql  and relay_log directories. The mysql directory must have mysql database with associated tables (should be copied from an existing database).

Note that the files were created on Ubuntu Lucid 10.04 and will likely not work on other distro. Also, the password in debian-330?.cnf files will be different for each DB and must be updated before use.
Use the following command to set the password:
GRANT ALL ON mysql.* to "debian-sys-maint"@"localhost" IDENTIFIED BY "dxaskDkdkSkdSDLd";

The bashrc file contains useful CLI shortcuts to common mysql commands. You are encouraged to add these to your own .bashrc file.

Laggy ssh with clear network

Recently, after reboot, my ssh sessions to remote servers started behaving sluggishly, sometimes taking several seconds for typed characters to appear. The lag was especially noticeable with last character that got typed. Nature of ssh sessions it to type several characters and checking the output. You can imagine the frustration seeing most of keypresses delivered, but getting feedback after some delay. Ping to the server was showing reliable, speedy responses with not a single packet loss. Network was in excellent shape, no torrents or other heavy uploads. I did not know where to look or how to google for the problem. I then remembered that I waited several months for the reboot to check an X-related crash and found that I disabled all X acceleration in the /etc/X11/xorg.conf file:

    Option "DRI" "false"
    Option "shadow" "true"
    Option "NoAccel" "True"

Desperate about the whole issue, I enabled back all X acceleration options, restarted X and voila! The ssh is fast again! Now, I don't know whether it is a bug or which subsystem it is in. So I decided to describe the problem sprinkled with keywords I used while googling for the problem in hope it helps someone. Write in comments if it did. :)

Playlist detection on python

There are several popular playlists used for internet radio streaming: asx, m3u, smil, asf, pls... The playlist extension is not always visible in the URL that an ipradio station returns. Furthermore, the MIME type is not always correct. Sometimes one has no choice but to guess the playlist type by looking for the presence of certain markers.

After fruitless searches on the internet, I wrote an python library that detects playlist type. You can download it here.

I am sure that the detection algorithm can be improved. Please write suggestions in the comments.

Easy creating and destroying of lxc vservers

One big advantage of using amazon's EC2 servce is its deceptively easy way to create new servers - it is just API call or mouseclick away. The actual physical machine allocation, OS image copying, hostname, IP, dns, firewall and routing setup are done transparently in the background. You are only required to setup the payment ;) .

Big enterprise virtualization technology providers already have a mechanism to create virtual machines with given parameters on demand. Such a system would likely be overkill for a handful of physical servers. I also doubt they support the highly effective pseudo-virtualization LXC technology.

Thus I created a python "lmachine" script for our LXC servers, that copies an OS image into a selected "slot" with already pre-allocated IP number and server name. The script also modifies a couple of system files from the OS image accordingly.

The script can be downloaded here.

Preparing an LXC image

LXC images are easily created using the debootstrap utility. To make them ready for the lmachine script, you need to set the actual IP number with the IPNUMBER string and the actual server name with the VSERVERNAME string. Here is the list of files that needs to be modified:

• fstab
• lxc.conf
• root/etc/network/interfaces
• root/etc/hosts
• root/etc/hostname
• root/etc/mailname

Make sure you pre-allocate IP numbers and ltestXX DNS domain names in advance. Update the lmachine script with the list of pre-allocated IP numbers.

xls2csv using python-uno

While several xls2csv converters exist, on a recent assignment none of them were able to convert a multi-sheet, 300+MB Excel file into CSV format.

While searching for possible solutions, I found this (dated) blog entry on using python-uno. After assembling it into a single script and updating for changed LibreOffice arguments, I made it available here. You can check the script using the sample .XLS file with three sheets.

The power of the solution lies in the LibreOffice+UNO (Universal Network Objects) platform it uses. While xls2csv looks like a trivial task, the platform automatically supports reading all spreadsheet types LibreOffice supports. This means that the script might as well be called xlsx2csv or ods2csv.

The script can become a starting point for someone trying to implement complex documents management automation scripts. Leave a comments if you do :) .

xkb files for russian and hebrew keyboard switchers

Long ago, my xkb-based keyboard switcher method stopped working. I then moved over to using gnome-keyboard-properties to set up the keyboard switching. This worked for another several years until recent ubuntu changes in oneiric that removed the stand-alone gnome-keyboard-properties. Worse yet, the gnome-control-center crashes on me if not running from gnome-session.

Being loyal user of FVWM2 window manager for 15 years (see my config over here), I dug out the xkb keyboard switching files and fixed them to work with the evdev keyboard type. This works on ubuntu oneiric (11.10) system.

Here are the download links to my xkb files:

• russian
• hebrew

To load them use the following command:

xkbcomp -R/usr/share/X11/xkb/ russian.xkb $DISPLAY