mechanix

Varnish cache stats on cacti

2009-02-20T14:01:00.000-08:00

Here are some stats I've developed for varnish to be monitored via cacti:
http://forums.cacti.net/post-156230.html

Drupal Boost rules for nginx

2009-02-10T12:47:00.001-08:00

Drupal has a nice module to boost its performance called Boost. It provides static page caching for anonymous users, i.e. it creates a static page for each url once it was requested. Static caching fully relies on rewrite rules, and Boost developers provide sample mod_rewrite rules to use with apache web server.

Unfortunately I couldn't find any working rules for nginx, so I have to develop them by myself. The main problem with nginx is that you can't specify multiple conditions. However there is a workaround (an ugly one, but it works).

Following lines should be inserted under "location /". Remember that order is important here, last rule is default drupal rule for nginx.

## Boost rewrite rules
set $boost "";

if ( $request_method = GET ) {
set $boost G;
}
if ($http_cookie !~ "DRUPAL_UID") {
set $boost "${boost}D";
}
if ($query_string = "") {
set $boost "${boost}Q";
}

if ( -f $document_root/cache/$host/0/index.html ) {
set $boost "${boost}I";
}

## GDQI, request is for main page
if ($boost = GDQI) {
rewrite ^/$ /cache/$server_name/0/index.html break;
}

if ( -f $document_root/cache/$host/0$request_uri.html ) {
set $boost "${boost}F";
}

## GDQIF, the request is for subpage
if ($boost = GDQIF) {
rewrite .? /cache/$server_name/0$request_uri.html break;
}

if ( -d $document_root/cache/$host/0$request_uri ) {
set $boost "${boost}E";
}
if ( -f $document_root/cache/$host/0$request_uri/index.html ) {
set $boost "${boost}F";
}
## GDQEF, the request is for module main page
if ($boost = GDQEF) {
rewrite .? /cache/$server_name/0$request_uri/index.html break;
}
## Boost rewrite rules end

if (!-e $request_filename) {
rewrite ^/(.*)$ /index.php?q=$1 last;
}

LDAP group based access for Drupal

2008-12-24T08:39:00.000-08:00

Sometimes you need to limit access to a Drupal instance to a single group in LDAP. Drupal has LDAP authentication module which works great. However, there is no way of setting group based access via its web interface.

The solution is to adjust ldapauth_user_filter function in sites/all/modules/ldap_integration/ldap_integration/ldapauth.conf.php. In order to allow users from "drupal_access" group only, change it to something similar to this:

function ldapauth_user_filter(&$attributes) {
if ($attributes['memberof'][0] == "CN=drupal_access,CN=Users,DC=domain,DC=local")
return TRUE;
else
return FALSE;
}

Python telnetlib "TypeError: 'in ' requires string as left operand" error

2008-12-03T04:20:00.000-08:00

If you receive following error while using telnetlib in python 2.X, you are hitting http://bugs.python.org/issue1772794 which is fixed in python 3.0

File "/usr/lib64/python2.5/telnetlib.py", line 289, in write
if IAC in buffer:
TypeError: 'in ' requires string as left operand

A fix for that in python 2.X can be forcing encoding of string you send to telnet, i.e. instead of
telnetconnection.write('just a test')

Use
telnetconnection.write('just a test').encode('latin-1'))

Using django ORM in a non-django project

2008-12-02T14:58:00.000-08:00

One of my latest project is split in 2 interconnected parts, one is using django framework for web interface and the other is third application scecific. And I thought of using django ORM in latter part to keep things simple and not to break anything in database. Quick lookup on internet gave me nothing, so I digged into it and found out that the only thing a script/application needs to use django ORM is DJANGO_SETTINGS_MODULE enviroment variable set. So here comes the solution:

import os

os.environ['DJANGO_SETTINGS_MODULE'] = 'myproject.settings'

from myproject.campaign.models import Campaign, List

The important thing here is not to try to import anything django-specific before actually setting enviroment variable. After that you will be able to use django ORM in your non-django project.

I really enjoy it

2008-09-08T14:35:00.000-07:00

From onwindows.com earlier last year (http://www.onwindows.com/Articles/LSE-TradElect-system-goes-live/843/Default.aspx) :

TradElect, the London Stock Exchange's new electronic trading system, has gone live.

The new technology platform has been developed using the Microsoft .NET Framework, with support from Microsoft and Accenture, and marks the final phase of the Exchange's four-year Technology Road Map project. TradElect enables significant increases in both speed of trading and system capacity.

From slashdot.com (http://tech.slashdot.org/article.pl?sid=08/09/08/185238):

"TradElect, the Microsoft .Net based trading platform for the London Stock Exchange, was offline for about seven hours, meaning that their 5-nines SLAs are shot for approximately the next 100 years. The TradElect system was launched back in June of 2007 and was designed for increased speed and system capacity."

Hurray to the MS based systems! Are there people that still think that MS can be reliable?

Sharing info

2008-06-26T06:29:00.000-07:00

Although I do have a personal mediawiki setup where I put info regarding tricks, tips and problem solutions, I thought it would be useful to share some of non confidential information with the community.