Lin He he9lin

Instrument Anything in Rails 3

With Rails 3.0 released a few weeks ago I've migrated a few apps and I'm constantly finding useful new improvements. One such improvement is the ability to log anything in the same way that Rails internally logs ActiveRecord and ActionView. By default Rails 3 logs look slightly spiffier than those produced by Rails 2.3: (notice the second line has been cleaned up)

Started GET "/" for 127.0.0.1 at Mon Sep 06 01:07:11 -0400 2010
  Processing by HomeController#index as HTML
  User Load (0.2ms)  SELECT `users`.* FROM `users` WHERE (`users`.`id` = 3) LIMIT 1
  CACHE (0.0ms)  SELECT `users`.* FROM `users` WHERE (`users`.`id` = 3) LIMIT 1

Rendered layouts/_nav.html.erb (363.4ms)

Note that this validation runs both after the file is uploaded and after CarrierWave has processed the image. If your base uploader includes a filter to resize the image then the validation will be run against the resized image, not the original one that was uploaded. If this causes a problem for you, then you should avoid using a resizing filter on the base uploader and put any specific size requirements in a version instead.

So instead of this:

require 'carrierwave/processing/mini_magick'

Setup Rails application production environment on Ubuntu

Add deploy user

ssh root@YOURDOMAIN
adduser deploy
visudo # Add deploy ALL=(ALL) ALL

Install necessary libraries

How to install PhantomJS on Ubuntu

Version: 1.9.8

Platform: x86_64

First, install or update to the latest system software.

sudo apt-get update
sudo apt-get install build-essential chrpath libssl-dev libxft-dev

In many production systems you'll want to have one module capable of talking to many potential implementations of a collaborator module (e.g a in memory cache, a redis-based cache etc). While testing it's useful to control which module the module under test is talking to.

Here are the approaches I can see. The two points that seem to divide the approaches are their tool-ability (dialyzer) and their ability to handle stateful implementations (which need a pid).

Passing modules

Modules are first class, so you can pass them in. Used in EEx, where passed module must implement a behaviour.

	class Api::RegistrationsController < Api::BaseController

	respond_to :json
	def create

	user = User.new(params[:user])
	if user.save
	render :json=> user.as_json(:auth_token=>user.authentication_token, :email=>user.email), :status=>201
	return
	else

	class OauthController < ApplicationController

	class ApiOAuthError < StandardError

	attr_accessor :code, :description, :uri, :state

	def initialize(code, description, uri = nil, state = nil)
	@code = code
	@description = description
	@uri = uri

	#!/usr/bin/env bash
	apt-get -y update
	apt-get -y install build-essential zlib1g-dev libssl-dev libreadline5-dev libyaml-dev
	cd /tmp
	wget ftp://ftp.ruby-lang.org/pub/ruby/1.9/ruby-1.9.3-p125.tar.gz
	tar -xvzf ruby-1.9.3-p125.tar.gz
	cd ruby-1.9.3-p125/
	./configure --prefix=/usr/local
	make
	make install

	#
	# PREDICTING LONG TERM CUSTOMER VALUE WITH BTYD PACKAGE
	# Pareto/NBD (negative binomial distribution) modeling of
	# repeat-buying behavior in a noncontractual setting
	#
	# Matthew Baggott, [email protected]
	#
	# Accompanying slides at:
	# http://www.slideshare.net/mattbagg/baggott-predict-customerinrpart1#
	#

	#!/bin/bash

	# generate new personal ed25519 ssh keys
	ssh-keygen -o -a 100 -t ed25519 -f ~/.ssh/id_ed25519 -C "rob thijssen <[email protected]>"
	ssh-keygen -o -a 100 -t ed25519 -f ~/.ssh/id_robtn -C "rob thijssen <[email protected]>"

	# generate new host cert authority (host_ca) ed25519 ssh key
	# used for signing host keys and creating host certs
	ssh-keygen -t ed25519 -f manta_host_ca -C manta.network