facter script that create custom facts on the memory of the node

mem_size.rb

require 'facter'

{   :MemorySizeRaw => "MemTotal",
    :MemoryFreeRaw => "MemFree",
    :SwapSizeRaw   => "SwapTotal",
    :SwapFreeRaw   => "SwapFree"
}.each do |fact, name|
    Facter.add(fact) do
        confine :kernel => :linux
        setcode do
            memsize_raw = ""
            Thread::exclusive do
                File.readlines("/proc/meminfo").each do |l|
                    memsize_raw = $1.to_i if l =~ /^#{name}:\s+(\d+)\s+\S+/
                    # MemoryFree == memfree + cached + buffers
                    #  (assume scales are all the same as memfree)
                    if name == "MemFree" &&
                        l =~ /^(?:Buffers|Cached):\s+(\d+)\s+\S+/
                        memsize_raw += $1.to_i
                    end
                end
            end
            memsize_raw
        end
    end
end