November 19th, 2009
preamble
Even on mid-size applications logs grow enormously fast, it’s a pity Rails doesn’t provide built-in functionality for that like Apache web-server does. Fortunately there is an easy and fast solution for that issue.
1. Install cronolog
“cronolog [http://cronolog.org/] is a simple filter program that reads log file entries from standard input and writes each entry to the output file specified by a filename template and the current date and time.”
For details, and list of parameters see: [http://cronolog.org/usage.html]
On GNU/Linux Debian:
# apt-get install cronolog
2. Setup your Rails application
Edit necessary environment file: like ‘config/environments/production.rb’ file
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| # system logger configuration
# config.logger = SyslogLogger.new
config.logger = Logger.new(IO.popen("FULL_PATH_TO_CRONOLOG log/production.log.%Y%m%d", "w"))
config.logger.level = Logger::INFO |
That’s all, fast and easy .. Enjoy!
Tags: Rails, RoR
Posted in ruby, web-development | No Comments »
November 2nd, 2009
We have common task: image scaling [http://en.wikipedia.org/wiki/Image_scaling], and correct understanding that: we can’t ask users to provide image of appropriate sizes, just use width and height CSS parameters for images, and thumbnail is always required feature.
Luckily we have ImageMagic library [http://www.imagemagick.org] and program interfaces for popular languages.
install RMagic gem
# gem install rmagick
add small code:
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| require 'rubygems'
require 'RMagick'
class ImageController < ApplicationController
def index
# determine basic params
w = params[:w]
h = params[:h]
path = params[:path]
if !w.to_s.empty? && !h.to_s.empty? && File.exists?(path)
begin
image = Magick::Image.read(path).first
transformed_image = image.resize_to_fill(w.to_i, h.to_i)
# send image
send_data(transformed_image.to_blob, :disposition => 'inline',
:type => "image/#{image.format.downcase}")
rescue Exception => e
Rails.logger.error e.message
Rails.logger.error e.backtrace.join("\n")
render :text => "Error processing image #{type}/#{aliaz}", :code => 404, :layout => false
end
end
end |
Here to re-size images we use ‘resize_to_fill’ ImageMagic method:
re-size the image to fit within the specified dimensions while retaining the aspect ratio of the original image, and if necessary, crop the image in the larger dimension.
Sure you understand that resizing takes time and so you should cache re-sized images.
For additional info look thru:
[http://studio.imagemagick.org/RMagick/doc/]
Posted in ruby, web-development | No Comments »
September 3rd, 2009
preamble
Ruby on Rails is a great framework that still luck some common features, among them: multi-domain support.
Here I will describe fast solution that doesn’t work for every browser and another one that do the work.
Ok, you did your homework and google something like ‘ruby on rails multi-domain’.
Very often provided solution:
edit environment.rb
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| config.action_controller.session = {:domain => '.mydomain.com'} |
With that parameter Rails always read cookies from same domain. In real some browsers forbid for applications to read cookies from other domain due to insecurity of that operation. And as Mozilla Firefox in set of browsers that forbid that we just need another solution.
Now it’s clear that we should implement necessary functionality other way.
Here we go:
1. will store session ID in the database(by default Rails2 store it in cookies)
environment.rb:
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| config.action_controller.session_store = :active_record_store |
and then execute rake task that create necessary DB migration:
Apply it with: rake db:migrate.
2. setup session parameters
environment.rb:
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| require "rubygems"
require "active_support"
config.action_controller.session = {
:session_key => '_myapp_session_id', # session identification key
:secret => '89sHslddfsd98klasdKd', # hash code of session generator(make it random and longer)
:cookie_only => false,
:expire_after => 1.week, # TTL (time to live)
} |
3. let’s create session creation handler
application_controller.rb:
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| before_filter { |controller|
opts = controller.request.session_options
key = opts[:key]
# use session ID if it's passed
if controller.params[key]
# session initialization with old ID
controller.session[:nothing]
opts[:id] = controller.params[key]
controller.request.session_options = opts
# session initialization with new ID
controller.session[:nothing]
end
} |
4. session pass
We need to pass session ID as parameter when user change domain name, and within domain we still use cookie.
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| “#{request.session_options[:key]}” => request.session_options[:id] |
It’s wise to use session initialization before request.session_options[:id] invocation due to Rails use lazy loading, and session can be uninitialized.
Use something like: session[:nothing].
Pay attention that information that Rails get from cookie has bigger priority, and so if you have some parameter in cookie Rails will use it firstly.
Note:
An attacker can still steal you session ID by sniffing the network, or exploiting javascript, he/she gets the value from the cookie itself. If you care about security so much just use HTTPS.
Posted in internet, ruby, web-development | 4 Comments »
August 26th, 2009
Today even great application can die alone .. world has too many great applications.
me
Do you know what software development company sell?
Not just some abstract peace of software but application that can solve customer’s problems .. we should understand what customer wants from the application, what tasks he/she wants to solve with application.
We provide to customer our vision and suggest technology/platform/approach, customer provide ideas/plans/limitations .. together we will end with some satisfied result. But what then?
Then as usual we get our money and leave customer alone with his application.
What else we can give to them?
We should give business advices that can bring closer customer’s target.
Client can take them or not but part of our work is to give ones. Customers see that we care, that help to build better relationship and get great satisfaction .. we make great applications that work!
Posted in be smart, business, internet | No Comments »
August 12th, 2009
preamble
Everybody who works with ruby on rails more then month knows at least 2 things:
it’s great framework, but can’t handle multiple requests simultaneously due to it still doesn’t use threads.
fast start
As scalability is common issue, rubyonrails site wiki provides full set of solutions:
[http://wiki.rubyonrails.org/#deployment_stacks]
But we as fast solution will use great OpenBSD pf (Packet Filter) that capable to do many cool things.
First issue is standard mongrail cluster that can start several instances of mongrail can only create them on one IP with different ports,
and pf can’t distribute requests among different ports on same IP.
Here we can create 2 simple scripts that start and destroy server instances:
# cat start.sh
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| count=1
for ip in 10.0.0.1 10.0.0.2 10.0.0.3 10.0.0.4 10.0.0.5
do
mongrel_rails start -e production -d --user myapp --group myapp --chdir /var/www/railsdocs/myapp \
--address ${ip} \
--pid /var/www/railsdocs/myapp/tmp/pids/mongrel.${count}.pid \
--log /var/www/railsdocs/myapp/log/mongrel.${count}.log
count=$(($count + 1))
done |
# cat stop.sh
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| for instance in {1..5}
do
mongrel_rails stop --wait 3 --chdir /var/www/railsdocs/myapp \
--pid /var/www/railsdocs/myapp/tmp/pids/mongrel.${instance}.pid
end |
And we need to enable pf:
#/etc/rc.conf.local
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| pf=YES
#pflogd_flags= # add more flags, ie. "-s 256" |
add one string to configuration file for load distribution:
#/etc/pf.conf
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| rdr pass log on re0 proto tcp from any to SOME_IP port 80 ->
{10.0.0.1, 10.0.0.2, 10.0.0.3, 10.0.0.4, 10.0.0.5 } port 3000 round-robin |
check work with:
# pfctl -s nat
monitor with:
tcpdump -n -e -ttt -i pflog0
for more info on pf:
http://www.openbsd.org/faq/pf/
man pf.conf (especially ‘TRANSLATION’ and ‘POOL OPTIONS’ sections)
Then when you see you need more advanced solution for load distribution you can install haproxy.
Check it with [http://www.openbsd.org/4.5_packages/i386/haproxy-1.3.15.7.tgz-long.html]
Posted in internet, openBSD, ruby, web-development | 1 Comment »
