refactoring: extract shared code into exchange

README.md

@@ -0,0 +1 @@
+realtime charts of amazon ec2 spot prices.

app/exchange.rb

@@ -1,3 +1,7 @@
+require 'time'
+require 'rubygems'
+require 'twitter'
+
 class Exchange
 
   def regular_price(which)
@@ -7,9 +11,92 @@ def regular_price(which)
   def spot_price(which)
     spot_price_map[which]
   end
+
+  def update_prices
+    current = {}
+    ['us-east-1', 'us-west-1', 'eu-west-1'].each do |region|
+      fetch_region(region)
+      data = parse_region(region)
+      store_region(region, data)
+
+      data.keys.each do |type|
+        which = "#{region}.#{type}"
+        price = data[type].last[1]
+        current[which] = price
+      end
+    end
+    store_prices(current)
+  end
 
 private
 
+  def fetch_region(region)
+    puts "#{Time.now} - fetching #{region}"
+    last = Time.parse(`tail -1 #{history_file(region)}`.split[2])
+    open(history_file(region), 'a') do |file|
+      url = "https://#{region}.ec2.amazonaws.com"
+      start = last.strftime('%Y-%m-%dT%H:%M:%S')
+      `ec2-describe-spot-price-history --url #{url} --start-time #{start}`.each do |line|
+        if Time.parse(line.split[2]) > last
+          file.puts line
+          puts line
+        end
+      end
+    end
+  end
+
+  def parse_region(region)
+    data = {}
+    open(history_file(region), 'r').each do |line|
+      col = line.split
+      price = col[1].to_f
+      stamp = Time.parse(col[2]).utc
+      inst = col[3]
+      os = col[4].split('/')[0].downcase
+      type = "#{os}.#{inst}"
+      values = data[type] ||= []
+      values << [stamp - 1, values.last[1]] unless values.empty?
+      values << [stamp, price]
+    end
+    data.each do |type, values|
+      values << [Time.now.utc, values.last[1]]
+    end
+    data
+  end
+
+  def store_region(region, data)
+    data.keys.each do |type|
+      which = "#{region}.#{type}"
+      atomic_write("#{data_dir}/#{which}.csv") do |file|
+        data[type].each do |stamp, price|
+          file.puts "#{stamp.strftime('%Y-%m-%d %H:%M:%S')},#{price}"
+        end
+      end
+      price = data[type].last[1]
+      percent = (price / regular_price(which) * 100).round
+      old_price = spot_price(which)
+      tweet(which, price, percent) if old_price and old_price.to_s != price.to_s
+    end
+  end
+
+  def tweet(which, price, percent)
+    password = open(File.join(File.dirname(__FILE__), '..', '.twitter')).read.chomp
+    client = Twitter::Base.new(Twitter::HTTPAuth.new('cx_ticker', password))
+    url = "http://cloudexchange.org/charts/#{which}.html"
+    message = "#{which} — $#{'%.3f' % price} — #{percent}% — #{url}"
+    puts message
+    client.update message
+  rescue Crack::ParseError => ignored
+  end
+
+  def store_prices(data)
+    atomic_write("#{data_dir}/spot.csv") do |file|
+      data.each do |type, price|
+        file.puts "#{type},#{price}"
+      end
+    end
+  end
+
   def regular_price_map
     @regular_price_map ||= price_map('regular')
   end
@@ -26,9 +113,21 @@ def price_map(name)
     end
     result
   end
+
+  def history_file(region)
+    "#{data_dir}/history.#{region}.txt"
+  end
 
   def data_dir
     "#{File.dirname(__FILE__)}/public/data"
   end
 
+  def atomic_write(path)
+    tmpfile = "/tmp/ruby.#{rand}"
+    open(tmpfile, 'w') do |file|
+      yield file
+    end
+    `mv #{tmpfile} #{path}`
+  end
+
 end

app/updater.rb

@@ -0,0 +1,6 @@
+#!/usr/bin/env ruby
+
+require File.join(File.dirname(__FILE__), 'exchange')
+
+exchange = Exchange.new
+exchange.update_prices

config/buildout.sh

@@ -55,13 +55,4 @@ vi .profile
   export PATH=$EC2_HOME/bin:$PATH
 
 #cronjob
-crontab -e
-
-  JAVA_HOME=/usr/lib/jvm/java-6-openjdk
-  EC2_URL=https://eu-west-1.ec2.amazonaws.com
-  EC2_PRIVATE_KEY=/home/ubuntu/.ec2/pk-TM374PQ4KXOLLOWN5DUYXYB3M3EX3IQP.pem
-  EC2_CERT=/home/ubuntu/.ec2/cert-TM374PQ4KXOLLOWN5DUYXYB3M3EX3IQP.pem
-  EC2_HOME=/home/ubuntu/ec2-api-tools-1.3-46266
-  PATH=/home/ubuntu/ec2-api-tools-1.3-46266/bin:/opt/ruby/bin:/usr/local/bin:/usr/bin:/bin
-
-  */5 * * * * /home/ubuntu/cloudexchange.org/fetch_history.rb >> /home/ubuntu/cloudexchange.org/cron.log 2>&1
+crontab -e