activerecord_script.rb

#!/usr/bin/env ruby 
require 'rubygems'
require 'activerecord' 
require 'spec'

class DiskFreeSpace < ActiveRecord::Base; end

class DiskFreeSpaceRunner
  
  def initialize(environment = 'production')
    establish_database(environment)
  end

  def collect
    `df -h`.to_a.each do | line |
      next if line =~ /^Filesystem/
      filesystem, size, used, available, capacity, mounted_on = line.chomp.split(/\s+/)
      DiskFreeSpace.create!(
        :filesystem => filesystem, 
        :size => size,
        :used => used, 
        :available => available,
        :capacity => capacity,
        :mounted_on => mounted_on
       )
    end
  end
  
  def report
    DiskFreeSpace.find(:all).each do | df |
      puts "#{df.created_at.strftime("%Y-%m-%d %H:%M:%S")} " + 
        "#{df.filesystem} #{df.size} #{df.used} #{df.available} #{df.capacity} #{df.mounted_on}"
      puts "-" * 80
    end
  end
  
  def establish_database(environment)
    ActiveRecord::Base.establish_connection( 
      :adapter => "sqlite3",
      :dbfile => "#{File.basename($0, '.rb')}_#{environment}.db"
    ) 

    unless  ActiveRecord::Base.connection.tables.include?("disk_free_spaces")
      ActiveRecord::Schema.define do
        create_table :disk_free_spaces do |t|
          t.string :filesystem
          t.string :size
          t.string :used 
          t.string :available 
          t.string :capacity
          t.string :mounted_on
          t.timestamps
        end
      end
    end
  end
end

if __FILE__ == $0 
  
  unless ARGV.size == 1 
    puts "\nusage: #{__FILE__} {collect|report|test}\n\n"
    exit 1
  end
  
  case ARGV.shift
  when 'report'
    DiskFreeSpaceRunner.new.report
  when 'collect' 
    DiskFreeSpaceRunner.new.collect
  when 'test'
    runner = DiskFreeSpaceRunner.new('test')

    describe DiskFreeSpace do 
      before(:each) do 
        now = Time.now
        Time.stub!(:now).and_return(now)
        DiskFreeSpace.delete_all 
        df_h = "Filesystem     Size   Used  Avail Capacity  Mounted on\n" +
        "/dev/disk0s2   96Gi   87Gi  8.4Gi    91%    /\n" + 
        "devfs         122Ki  122Ki    0Bi   100%    /dev\n" 
        runner.should_receive(:`).with("df -h").and_return(df_h)
        runner.collect
      end

      it "should collect disk free space data" do
        dfs = DiskFreeSpace.find(:all)
        dfs.size.should == 2 
        df = dfs.first
        df.filesystem.should == "/dev/disk0s2"
        df.size.should == "96Gi"
        df.used.should == "87Gi"
        df.available.should == "8.4Gi"
        df.capacity.should == "91%"
        df.mounted_on.should == "/"

        df = dfs.last
        df.filesystem.should == "devfs"
        df.size.should == "122Ki"
        df.used.should == "122Ki"
        df.available.should == "0Bi"
        df.capacity.should == "100%"
        df.mounted_on.should == "/dev"
      end

      it "should report disk free space data" do
        runner.should_receive(:puts).with("#{Time.now.strftime("%Y-%m-%d %H:%M:%S")} /dev/disk0s2 96Gi 87Gi 8.4Gi 91% /")
        runner.should_receive(:puts).with("#{Time.now.strftime("%Y-%m-%d %H:%M:%S")} devfs 122Ki 122Ki 0Bi 100% /dev")
        runner.should_receive(:puts).with("-" * 80).twice
        runner.report
      end
    end
  else
    puts "Unrecognized option"
  end
end