Can Burak Çilingir

Halal and Organik Logos for Indonesia

2013-04-03T00:00:00-07:00

If you need “Halal” and “Organik” logos for Indonesia, here they are:

Halal Logo

Organik Logo

Integrating Mandrill and Postfix

2012-05-17T00:00:00-07:00

I was looking around for transactional email solutions and decided to test Mandrill. The easiest test case for me was to setup my laptop to relay over it. I am using Ubuntu 12.04. You can find your credentials in the settings page.

An easier method would be using swaks:

swaks --to YOUR_EMAIL \
      --server smtp.mandrillapp.com \
      --auth-user YOUR_USERNAME \
      --auth-password YOUR_API_KEY

First step is to set a fully qualified domain as your hostname. Check if hostname -f outputs an fqdn. On my laptop it nicely displayed gem.canb.net, so I was good to go. Please configure your hostname if it is not an FQDN. You can do it with hostname YOUR_FQDN. If you want this to survive a reboot, you are on your own.

Add this domain to your Mandrill account as outbound and set-up the DNS records as instructed by the DNS Settings button.

From now on, I’ll be closely following Postfix SASL documentation. Put the following into /etc/postfix/sasl_passwd:

[smtp.mandrillapp.com] YOUR_USERNAME:YOUR_API_KEY

Secure the file with chown root:root and chmod go-rwx and run postmap /etc/postfix/sasl_passwd. You’ll need postmap anytime you change your credentials.

Modify /etc/postfix/main.cf:

myhostname = gem.canb.net
mydestination = gem.canb.net, gem, localhost.localdomain, localhost

smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options = noanonymous

relayhost = [smtp.mandrillapp.com]:587

If you are going to use this setup for a longer time period, you have to setup TLS as we are sending everything in plaintext, thanks to smtp_sasl_security_options = noanonymous.

Restart Postfix and you can ps aux | mail -s test YOUR_EMAIL. You can tail -f /var/log/syslog to see what’s happening.

Jekyll and zenhabits

2012-04-03T00:00:00-07:00

Like all geeks I’ve tried many blogging solutions over the years and I always thought that latest one is the ultimate one.

This time is no different. I’ve switched from blogger.com to a ~~self-hosted~~ github-hosted jekyll.

After spending some time with vst, we were happy with jekyll. Bolts and nuts are in place. I searched for a decent theme and loved the Zen Habits theme.

Here I am with my ultimate blog solution.

Now I need another post to demote this one from the front page.

Story of an Analog POS

2012-02-18T00:00:00-08:00

I like to read Paul Venezia’s blog from time to time. He talks about things like MRJ21 cables or C19-to-L6-20 cables. Recently he wrote IT guy wanted; must have own tools which I remembered today when dealing with the problem I’ll talk about below.

Some of my work involves Brandsfever, which is a private shopping club in Singapore. Tomorrow we’ll have an offline sales event and I was unable to resist the idea of playing with a new toy, VeriFone Vx 510. When I had the device, I was ready to plug it to my laptop via one of my cisco console cables. Remembering how lucky guy I am, things didn’t go smooth and we realized that the device needs to operate on a good old analog phone line. I was expecting at least a SIM card or may be some Wi-Fi but I am still thankful that we don’t have to use a credit card imprint device.

It didn’t took long to realize that we are using elastix and we do not have any analog lines. Thankfully Melvin found a Linksys PAP2 buried in the IT drawer and configured it which provides us an analog line. After spending some time with the device we were able to charge my card 0.01$. We were ready for the event… A phone call disturbed my dream. We won’t have a line in the event’s place. I love problems to stack up. Thankfully I have my GPL’d portable wireless router which makes me the type of IT guy Venezia want. After spending some time configuring elastix and the Linksys device to work together over 3g, I’ve succeded to charge my credit card without a real phone line.

Hopefully, if you come to visit our event at 111 Somerset tomorrow, your card will be charged over a POS device which connects to the bank over a 3g connection with the help of a USB dongle connected to a wireless router, a Linksys PAP2 device and an Elastix server located in our office. It makes me feel like a hacker.

Please SingTel, don’t let us down! And thanks to Venezia for the inspiration to write this post.

Update: After a couple of charges over this system, luckily we were able to use a real phone line and switched back to the real analog for our charges. Now, I want to connect this to a computer.

Push data to google analytics with python

2012-01-16T00:00:00-08:00

I’ll share with you how to push data to Google Analytics with a simple Python example. You can collect/plot/analyze some interesting data:

If you have a programmable door lock in the office, you can track employees’ office hours.
Track the commits of your team. Tag with branch/hash etc.
Track your own computer usage

Google Analytics is mostly used with a JavaScript snippet on the client side but if you browse the documentation, you’ll see that they also provide mobile tracking features which help you to collect data without a web browser or even if the client doesn’t support JavaScript.

Basically, mobile client displays an image which is served by a server-side script hosted by you and the script pushes the visit data to Google via GET request. The parameters of this method is listed on Troubleshooting the Tracking Code section of the documentation.

After looking at this list and PHP/Perl codes provided by Google, with some trial and error I’ve found the minimum parameters to push data.

utmwv: tracking code version. The latest version at the time of this writing is 5.2.2d.

utmn: unique ID generated for each GIF request to prevent caching of the GIF image. Example value in the documentation is 10 digits so stick to maximum of 10 digits.

utmp: requested path of the current page.

utmac: account string (property id).

utmcc: cookie values. __utma is required. These 2 posts discusses this cookie in detail. 1 can be used for each part except unique visitor id. For the visitor id, you can generate something unique for each visitor which doesn’t change between visits. The safe assumption for the length of the id 10 because google Analytics itself uses around 10 digits.

After this data is generated, simply request http://www.google-analytics.com/__utm.gif with these parameters in the query string.

Here is the proof of concept Python code:

I’ve provided you the bare minimum. Now you can add more variables and track whatever you need. Don’t forget to share your hack in the comments.

How to serve static files with Pyramid

2012-01-11T00:00:00-08:00

If you want to host your Pyramid static files in s3 or compile everything to a local folder, just like Django’s collectstatic, van.static is to the rescue.

Before going further, ensure that all of your statics are resolved from the request object and any references from CSSs use relative paths. A Mako example would be: ${request.static_url("app:static/image.png")}.

Install van.static to your virtual environment with pip install van.static.

Setup van.static in your app’s entry point:

from van.static import cdn
static_resources = (('static', 'app:static'),)
cdn.config_static(config,
                  static_resources,
                  static_cdn=settings.get("static_cdn"))

If you want to collect all static files together:

python -m van.static.cdn --target=file:///srv/static/myapp/ --resource="app:static"

van.static has 2 modes. If you do not provide it a static_cdn parameter, it works in development mode and it serves everything via Pyramid’s static view. If you provide the parameter, it goes into oroduction mode and simply generates unique urls for each version of your application, prefixing the given URL.

The software is not even a month old but already can compress files with YUI compressor and seems to be pretty usable.

Automatically decorating all views of a django project

2010-01-06T00:00:00-08:00

Now the real thing, a middleware for Django.

This middleware auto-decorates each view function in a view module (views.py, or views/) with the decorators defined in settings.py.

An example setting is:

Think this middleware as a firewall. Whether you decorated your view functions or not, this ensures that your content is protected by using the decorators.

Note that this middleware needs to be at the end of the middlewares list because it always return an HttpResponse by calling the view function; which means no other middleware after this is executed.

Here is the function:

Emacs buffer coding system

2009-02-15T00:00:00-08:00

If emacs doesn’t recognize the encoding of your file, you can give it some tips to recognize it. For example, I have a file encoded as “iso-8859-9” but emacs is unable to display it properly.

The solution is not hard. You do a C-x RET c iso-8859-9, followed by C-x C-f, and you now have a properly encoded buffer.

To save this file in utf-8, you do a C-x RET c utf-8 C-x C-w.

If you have a problem with line coding, append a -dos, -unix or -mac while reading or writing the file.