jonasporto

Rails Migration

http://guides.rubyonrails.org/migrations.html

Migrations methods:

• add_column
• add_index
• change_column
• change_table
• create_table
• drop_table

jonasporto

supervisord [supervisord.org]
=============================

* Set up jobs via a config file (.ini style)

	Example:
	--------
	[program:forever]
	command=/usr/bin/python /root/supervisoreval/bin/forever.py &
	numprocs=1

jonasporto

On Tue Oct 27, 2015, history.state.gov began buckling under load, intermittently issuing 500 errors. Nginx's error log was sprinkled with the following errors:

2015/10/27 21:48:36 [crit] 2475#0: accept4() failed (24: Too many open files) 2015/10/27 21:48:36 [alert] 2475#0: *7163915 socket() failed (24: Too many open files) while connecting to upstream...

An article at http://www.cyberciti.biz/faq/linux-unix-nginx-too-many-open-files/ provided directions that mostly worked. Below are the steps we followed. The steps that diverged from the article's directions are marked with an *.

1. • Instead of using su to run ulimit on the nginx account, use ps aux | grep nginx to locate nginx's process IDs. Then query each process's file handle limits using cat /proc/pid/limits (where pid is the process id retrieved from ps). (Note: sudo may be necessary on your system for the cat command here, depending on your system.)
2. Added fs.file-max = 70000 to /etc/sysctl.conf
3. Added `nginx soft nofile 1

jonasporto

Virtual DOM and diffing algorithm

There was a [great article][1] about how react implements it's virtual DOM. There are some really interesting ideas in there but they are deeply buried in the implementation of the React framework.

However, it's possible to implement just the virtual DOM and diff algorithm on it's own as a set of independent modules.

jonasporto

#301 Redirects for .htaccess

#Redirect a single page:
Redirect 301 /pagename.php http://www.domain.com/pagename.html

#Redirect an entire site:
Redirect 301 / http://www.domain.com/

#Redirect an entire site to a sub folder
Redirect 301 / http://www.domain.com/subfolder/

jonasporto

import cv2.cv as cv
import tesseract
gray = cv.LoadImage('captcha.jpeg', cv.CV_LOAD_IMAGE_GRAYSCALE)
cv.Threshold(gray, gray, 231, 255, cv.CV_THRESH_BINARY)
api = tesseract.TessBaseAPI()
api.Init(".","eng",tesseract.OEM_DEFAULT)
api.SetVariable("tessedit_char_whitelist", "0123456789abcdefghijklmnopqrstuvwxyz")
api.SetPageSegMode(tesseract.PSM_SINGLE_WORD)
tesseract.SetCvImage(gray,api)
print api.GetUTF8Text()

jonasporto

Originally published in June 2008

When hiring Ruby on Rails programmers, knowing the right questions to ask during an interview was a real challenge for me at first. In 30 minutes or less, it's difficult to get a solid read on a candidate's skill set without looking at code they've previously written. And in the corporate/enterprise world, I often don't have access to their previous work.

To ensure we hired competent ruby developers at my last job, I created a list of 15 ruby questions -- a ruby measuring stick if you will -- to select the cream of the crop that walked through our doors.

What to expect

Candidates will typically give you a range of responses based on their experience and personality. So it's up to you to decide the correctness of their answer.

jonasporto

This list is based on aliases_spec.rb.

You can see also Module: RSpec::Matchers API.

matcher	aliased to	description
a_truthy_value	be_truthy	a truthy value
a_falsey_value	be_falsey	a falsey value
be_falsy	be_falsey	be falsy
a_falsy_value	be_falsey	a falsy value

jonasporto

# Simple approach to sending email from the Rails console
# Implementation idea courtesy of Steve Klabnik
# http://blog.steveklabnik.com/posts/2012-09-09-random-ruby-tricks--class-new

# Create the mailer class with a block and assign to a variable
mailer = Class.new(ActionMailer::Base) do
  def example_message
    mail(to: "[email protected]", from: "[email protected]", subject: "Example Message") do |format|
      format.text { render text: "Example message body" }
    end

jonasporto

AWS region code	AWS region name	Number of AZs	AZ names
us-east-1	Virginia	4	us-east-1a, us-east-1b, us-east-1c, us-east-1e
us-west-1	N. California	2	us-west-1a, us-west-1b
us-west-2	Oregon	3	us-west-2a, us-west-2b, us-west-2c
eu-west-1	Ireland	3	eu-west-1a, eu-west-1b, eu-west-1c
eu-central-1	Frankfurt	2	eu-central-1a, eu-central-1b
ap-southeast-1	Singapore	2	ap-southeast-1a, ap-southeast-1b
ap-southeast-2	Sydney	2	ap-southeast-2a, ap-southeast-2b, ap-southeast-2c
ap-northeast-1	Tokyo	2	ap-northeast-1a, ap-nort