Downloading files

Wow it's been a year since I've last posted!

I'm currently checking out dragonfly, the new kid on the block file processor. It's mean to replace stuff like paperclip and attachment_fu. To make things simple, especially if you don't have a lot of files, when migrating from either of those to dragonfly it may be simpler to just download the file and upload it again via dragonfly. This way you don't have to study the internals of each file management plugin.

So, here's how to download a file.

require 'net/http'

url = URI.parse "http://url.to/file.name"
Net::HTTP.start url.host do |http|
response = http.get url.path
MyModel.create! :file => response.body
# Here you tell your model to create the file.
# This is what the create action in the controller calls
# but instead of params[:file], you have response.body
end

Vim Setup

I've posted many a setup in vim before, but I've decided to put it on github for easier management.

Stars and acts_as_rateable

I recently wanted to implement a star system in Rails. I looked at this rateable plugin and followed this tutorial to create the stars.

It wasn't as cut and dried as I had hoped, so here is the code I used. It's pretty complete. Disclaimer: I used haml and sass and if you don't, you should still be able to understand the code. In case you don't use sass, here's the generated CSS that you get from the sass file.

before_create should return the right boolean!

This is a small thing, but I wasted an hour or so figuring this thing out. I had an a before_create where I set a boolean variable to false and then my tests started to fail? Why? Because before_create will stop the creation of the record if it returns false!

class A << AR::Base
 before_create :set_enabled

 def set_enabled
   self.enabled = false
   true # so that it doesn't fail
 end
end

Passenger, Monit, Postfix

Setting up Passenger was quite easy, coming from the world of Mongrel. For the most part I followed this. It's pretty comprehensive, but I'll just add some stuff that I had to do on my own.

This is far from a comprehensive list, and if you just follow this things won't work. This also assumes you have _some_ knowledge of how Postfix, Monit, Linux works.

Postfix
I accept and read mail somewhere else (not on the VPS that sends mail). For example, I may use Google to accept mail on the Internet, however, I don't connect my server to Google to send mail. Because of this, when postfix on my server tried to send mail to mydomain.com, it always something like "there is no user on this server". So I opened up /etc/postfix/main.cf and make sure that mydestination doesn't contain your domain name. mydestination tells postfix what resides on your local machine.

mydestination = localhost.localdomain, localhost

Also, to use it, my Rails app's setting were like this:

ActionMailer::Base.delivery_method = :smtp
ActionMailer::Base.smtp_settings = {
  :address => "localhost",
  :port => 25,
  :domain => "www.theinksquad.com"
}

SilverRack and Sources
Installing the clean 8.04 on SilverRack, /etc/apt/sources.list is virtually empty. You need to add:

deb http://ubuntu.media.mit.edu/ubuntu/ hardy main restricted universe multiverse
deb-src http://ubuntu.media.mit.edu/ubuntu/ hardy restricted main multiverse universe

deb http://ubuntu.media.mit.edu/ubuntu/ hardy-updates main restricted universe multiverse
deb-src http://ubuntu.media.mit.edu/ubuntu/ hardy-updates restricted main multiverse universe

deb http://security.ubuntu.com/ubuntu/ hardy-security main restricted universe multiverse
deb-src http://security.ubuntu.com/ubuntu/ hardy-security restricted main multiverse universe

Then "sudo apt-get update" after

Monit
The tutorial above didn't have any tutorial for Monit or God.rb. Install the dependencies first:

sudo apt-get install flex byacc bison -y

Then monit (Make sure this is the latest and greatest version):

wget http://mmonit.com/monit/dist/beta/monit-5.0_beta7.tar.gz
tar -xzvf monit-5.0_beta7.tar.gz && cd monit-5.0_beta7/ && sudo ./configure && sudo make && sudo make install && cd ../
sudo mkdir /etc/monit.d

Then make the monit file for Apache. This file basically tells monit what to watch out for, and how.

Sample /etc/monit.d/apache.monitrc

check process apache with pidfile /var/run/apache2.pid
  start program = "/etc/init.d/apache2 start"
  stop program = "/etc/init.d/apache2 stop"
  if cpu > 60% for 2 cycles then alert
  if cpu > 80% for 5 cycles then restart
  if totalmem > 200.0 MB for 5 cycles then restart
  if children > 250 then restart
  if loadavg(5min) greater than 20 for 8 cycles then alert
  group yourappnamehere

Since I use workling, I also made a seperate file for it:
server$ sudo vi /etc/monit.d/workling.monitrc
and paste (do a "which ruby" to find out where ruby is and replace the /usr/bin/ruby if needed)

check process workling with pidfile /var/www/yourappname/shared/log/workling.pid
  start program = "/bin/bash -c 'HOME=/var/www/yourappname/current RAILS_ENV=production /usr/bin/ruby /var/www/yourappname/current/script/workling_client start'"
  stop program = "/bin/bash -c '/usr/bin/ruby /var/www/yourappname/current/script/workling_client stop'"
  if totalmem is greater than 180.0 mb for 5 cycles then restart
  if cpu is greater than 90% for 5 cycles then restart
  if 20 restarts within 20 cycles then timeout
  group yourappname

Then reload monit via "sudo monit reload".

Now monit needs to be told to start automatically when we startup and when/if it crashes, we'll use upstart (this is for Ubuntu only?)

 server$ sudo vi /etc/event.d/service_monit

and paste (do a "which monit" to find out where monit is and replace the /usr/local/bin/monit if needed)

# This is an event.d (upstart) script to keep monit running
# To install disable the old way of doing things:
#
# /etc/init.d/monit stop && update-rc.d -f monit remove
#
# then put this script here: /etc/event.d/monit
#
# You can manually start and stop monit like this:
# 
# start monit
# stop monit
#
# Michael Hale (http://halethegeek.com)

start on startup
start on runlevel 2
start on runlevel 3
start on runlevel 4
start on runlevel 5

stop on runlevel 0
stop on runlevel 6

exec /usr/local/bin/monit -Ic /etc/monit/monitrc
respawn

Moving To Passenger, Workling

I've used backgroundrb for a while now. Coupled with mongrels, monit, it wasn't a pleasant experience. Oh, I forgot to mention that I was learning Linux at the time (still am actually), so it was very difficult for me.

Lately, I've been comtemplating moving my production environment to Passenger, Apache, Workling and God. The next few posts will talk about my experience and what I did. :)

For now, let me just say that this help page played a big part in speeding up my staging.

Cleaning Up Your ActiveRecord Sessions

I was looking for a way to do this and found a good resource to find out how (without coding it yourself!)

http://www.quarkruby.com/2007/10/21/sessions-and-cookies-in-ruby-on-rails#sexpire refers to a plugin called limited session but the link is no longer valid. Check out http://iprog.com/project/limited_sessions

Update: this breaks in Rails 2.3, I think it's because of the lazy loading. I've never learned much about sessions, so for now I'll move back to file stored.