A Noted Path by Theodore Nguyen-Cao

If you’ve been following my blog for awhile, you might have noticed I moved this blog from blog.notedpath.com to theodorenguyen-cao.com as it was more fitting domain. I originally just registered the domain, added the DNS record, and updated my apache config to have theodorenguyen-cao.com to be an server alias to blog.notedpath.com.

This allowed requests to blog.notedpath.com/* and theodorenguyen-cao/* respond with the same content. I thought I was done. I discovered this wasn’t the case when I saw blog.notedpath.com as a direct traffic source in my google analytics for theodorenguyen-cao.com. To fix the screwed up analytics, I needed to make it so that all requests that go to blog.notedpath.com are permanently redirected (301) to theodorenguyen-cao.com.

To do this I had to apply an Apache mod_alias redirect directive as such:

<VirtualHost *:80>
        VirtualDocumentRoot /var/www/blog
        ServerName blog.notedpath.com
        Redirect permanent / http://www.theodorenguyen-cao.com/
        ErrorLog /var/log/apache2/wp-error.log
        TransferLog /var/log/apache2/wp-access.log
</VirtualHost>

The virtual host for theodorenguyen-cao.com looks like:

<VirtualHost *:80>
    VirtualDocumentRoot /var/www/blog
    ServerName www.theodorenguyen-cao.com
    ServerAlias theodorenguyen-cao.com
    CustomLog /var/log/apache2/theodorenguyen-cao.com_access.log Combined
    ErrorLog /var/log/apache2/theodorenguyen-cao_error.log
</VirtualHost>

At first I thought this would only fix the simple case of blog.notedpath.com redirecting to theodorenguyen-cao.com, but blog.notepath.com/foobar not being translated to theodorenguyen-cao.com/foobar. However, this does exactly what I want. All blog.notedpath.com URLs will be replaced with theodorenguyen-cao.com URLs. Old bookmarks will simply redirect to a theodorenguyen-cao.com URL and not 404.

Success!

I’m still waiting to see if Google will update the search result links that point to blog.notedpath.com to be theodorenguyen-cao.com URLs.

rsvp.theoandpat.com had boolean flag to marked whether or not a visitor was going to be able to make it to our wedding. Unfortunately, if you selected you were not able to make it and submit the form, the application would return saying it could not process your submission because you have to say that you are going to make it. I argued, this is an RSVP form so you have to accept if you are RSVPing. That’s the point of the RSVP! Only people RSVP would bother submitting the form!  Pat wasn’t too happy about that and ask/told me to fix it. 

Digging into it, it turns out the way  for validates_presence_of relies on Object#blank which of course when sent

false.blank? # returns true

Reading up on the documentation, it is suggested to use validates_inclusion_of when dealing with booleans.

The one line change solved the problem:

validates_inclusion_of :accepted, :in => [true, false]

Inspired by a discussion of URL shortening, I took a weekend and implemented one of my own. When thinking about tiny URLs, a quote always came to mind.

Don’t use a big word where a diminutive one will suffice.

So after finding out the domain was available, diminutiveurl.com was born. Yes, it’s poking a little fun at the idea of a tiny url but it was fun to hack on. It’s very minimilistic at this point but I hope to add some interesting features.

For no other reason than to build something, I hope you enjoy it! I am glad to present diminitiveurl.com! Please let me know what you think.

I had heard of mod_rails awhile back but never had the time to take a closer look at it. While setting up a new rails app, I was getting frustrated with all of the configuration I needed to do to get the mongrel clusters and proxy balancers setup. So I decided to give passenger a chance. I’m a fan now

The process was dead simple.

1. Install the passenger gem

   sudo gem install passenger

2. Install passenger as an Apache module

   passenger-install-apache2-module

3. Load the passenger apache module by editing the Apache config

   LoadModule passenger_module /usr/lib/ruby/gems/1.8/gems/passenger-2.0.5/ext/apache2/mod_passenger.so
   PassengerRoot /usr/lib/ruby/gems/1.8/gems/passenger-2.0.5
   PassengerRuby /usr/bin/ruby1.8
   

4. Restart Apache

If all things went well, you have everything installed you need. If there were some missing dependencies, you should be presented with how to install those dependencies.

In the installation output, it tells you how to mod_railsify your apps by creating a vhost as such:

<VirtualHost *:80>
    ServerName www.mywebsite.com
    DocumentRoot /home/deploy/mywebsite/public
</VirtualHost>

That’s it! No more of this proxy balancer and mongrel_cluster.yml configuration.

There’s some magic going on in the background. As requests come in, passenger will spin up more application instances. For more tweaking your configuration options check out the user guide.

Go to your website and you should see your rails app up and running.

So now we have your app up and running, how do we update or restart our app? Passenger provides two ways for us to do this.

The first is whenever apache is restarted, your application is restarted.

The second way allows us to restart a specified application without affecting Apache. Whenever passenger detects tmp/restart.txt, it will restart the application instances for us. We can integrate this into our Capistrano deploy flow by adding the following our config/deploy.rb

namespace :passenger do
  desc "Restart Application"
  task :restart do
    run "touch #{current_path}/tmp/restart.txt"
  end
end

after :deploy, "passenger:restart"

This will create that restart.txt after the cap:deploy task gets executed, causing the application to restart.

Finally, passenger comes with some pretty useful utilities.

Check out passenger-status which produces output showing current passenger server statuses.

Sample output:

----------- General information -----------
max      = 6
count    = 1
active   = 0
inactive = 1
Using global queue: no
Waiting on global queue: 0

----------- Applications -----------
/home/deploy/www.myapp.com/releases/20081206183156:
  PID: 30784     Sessions: 0

Another utility passenger-memory-status gives you insight into how much memory is being used by apache and passenger.

Sample output:

-------------- Apache processes ---------------
PID    PPID   Threads  VMSize    Private  Name
-----------------------------------------------
12841  1      1        225.9 MB  0.0 MB   /usr/sbin/apache2 -k start
28294  12841  1        248.4 MB  21.4 MB  /usr/sbin/apache2 -k start
28300  12841  1        243.7 MB  0.5 MB   /usr/sbin/apache2 -k start
28306  12841  1        248.4 MB  4.4 MB   /usr/sbin/apache2 -k start
28357  12841  1        249.1 MB  19.8 MB  /usr/sbin/apache2 -k start
29400  12841  1        249.4 MB  3.7 MB   /usr/sbin/apache2 -k start
29788  12841  1        249.3 MB  21.7 MB  /usr/sbin/apache2 -k start
29834  12841  1        245.8 MB  18.9 MB  /usr/sbin/apache2 -k start
29836  12841  1        245.8 MB  9.3 MB   /usr/sbin/apache2 -k start
29868  12841  1        245.8 MB  2.4 MB   /usr/sbin/apache2 -k start
29870  12841  1        246.5 MB  5.2 MB   /usr/sbin/apache2 -k start
### Processes: 11
### Total private dirty RSS: 107.44 MB

--------- Passenger processes ----------
PID    Threads  VMSize    Private  Name
----------------------------------------
28031  10       15.3 MB   0.1 MB   /usr/lib/ruby/gems/1.8/gems/passenger-2.0.5/ext/apache2/ApplicationPoolServerExecutable 0 /usr/lib/ruby/gems/1.8/gems/passenger-2.0.5/bin/passenger-spawn-server  /usr/bin/ruby1.8  /tmp/passenger_status.12841.fifo
28032  2        48.7 MB   0.6 MB   Passenger spawn server
29161  1        114.8 MB  0.7 MB   Passenger FrameworkSpawner: 2.1.2
30461  1        122.8 MB  32.3 MB  Passenger ApplicationSpawner: /home/deploy/www.myapp.com/releases/20081206183156
30784  1        129.3 MB  33.4 MB  Rails: /home/deploy/www.myapp.com/releases/20081206183156
### Processes: 5
### Total private dirty RSS: 67.08 MB

Pretty sweet.

I fired up Photoshop for the first time in a long time. I created a transparent PNG for an image that would be used as a CSS background-image. It keeps displaying with a gray background even though the page background color was something else.

This is a pretty well documented bug. Luckily, there are a couple of ways to fix this.

Here are my two favorites:

The first solution is well documented:

Download iepngfix.zip. The development version 2.0 Alpha 3 has support for background position and repeat. Extract the zip and copy iepngfix.htc and blank.gif somewhere. I put in under stylesheets.

Add the following snippet to your CSS stylesheet:

img {
	behavior: url(/stylesheets/iepngfix.htc);
}

And you’re done! Hit refresh in IE6 and transparent PNG images should render correctly now.

You can add apply this fix to other elements that may be using PNG images as CSS background images as such:

img, #logo {
	behavior: url(/stylesheets/iepngfix.htc);
}

where logo is a div that has a background-image that is a transparent PNG.

Note: If you are using v2.0 and want to take advantage of background-repeat and position support, copy iepngfix_tilebg.js to your javascripts folder and include the js file in the HTML files you need it for.

The second way to fix this is to get everyone off IE6 but I guess that’s just wishful thinking…