Working around the chef azure cookbook -- no blob download method... here, let me write one for you :-/ Will need to rewrite to integrate with actual cookbook.

azure_get_blob.rb

require 'azure'


# run looks like this
#
# $ ruby get_blob.rb
# write-pdf - length: 9613706, last-modified: Fri, 27 Jun 2014 18:28:49 GMT
# Target content length: 9613706
# --- progress 43.63 percent, time: 29.08 s
# --- progress 87.26 percent, time: 26.68 s
# --- progress 100.00 percent, time: 25.49 s
# 
# Total dl time: 81.25 seconds
# Avg dl rate: 0.1128  MBytes/sec
 
MB=1024*1024
CHUNK_MAX=4*MB

storage_account = "<you create this>"
account_key="<you create this>"

def create_container(abs)
  abs.create_container(container_name)
end

def upload_blob(abs, container_name, file_name, blob_name)
  # Upload a Blob
  print "uploading file: #{file_name} to blob: #{blob_name}\n"
  content = File.open(file_name, 'rb') { |file| file.read }
  abs.create_block_blob(container_name, blob_name, content)
end

def list_containers(abs)
  # List containers
  abs.list_containers()
end

def list_blobs(abs, container_name)
  # List Blobs
  abs.list_blobs(container_name).each do |blob|
    print "#{blob.name} - length: #{blob.properties[:content_length]}, last-modified: #{blob.properties[:last_modified]}\n"
  end
end


def dl_blob(abs, container_name, blob_name, write_name)
  content_length=-1
  # check if exists
  abs.list_blobs(container_name).each do |blob|
    if blob.name == blob_name
      content_length=blob.properties[:content_length]
      print "Target content length: #{content_length}\n"
    end
  end
  if content_length == -1
    "Content length -1 -- aborting"
    return
  end

  # if write_name exist, copy to .1?   or something
  if File.exists?(write_name)
    File.rename(write_name, "#{write_name}.1")
  end

  blob_pointer=0
  File.open(write_name, "wb") do |f|
    total_time=0.0
    while blob_pointer < content_length
       #loop
      # NOTE: 4MB is max size chunk azure can handle
      blob_end_pointer = blob_pointer + CHUNK_MAX
      #print "to block #{blob_end_pointer}\n"
      if blob_end_pointer > content_length
        blob_end_pointer = content_length
      end
      # do your work
      t1 = Time.now
      blob, content = abs.get_blob(container_name, blob_name)
      t2 = Time.now
      delta = t2 - t1
      total_time += delta
      printf "--- progress %.2f percent, time: %.2f s\n", (blob_end_pointer.to_f/content_length.to_f * 100).to_f, delta
      f.write(content)
      blob_pointer = blob_end_pointer+1
    end
    print "\nTotal dl time: %.2f seconds \n" % total_time
    print "Avg dl rate: %.4f  MBytes/sec\n" % (content_length.to_f/1024/1024/total_time.to_f)
  end
end

def delete_blob(abs, container_name, blob_name)
  # Delete a Blob
  abs.delete_blob(container_name, blob_name)
end

def blob_test(bs, container_name, name, blob_name)
  upload_blob(bs, container_name, name, blob_name )
  list_blobs(bs, container_name)
  dl_blob(bs, container_name, blob_name, "#{name}.new")
  delete_blob(bs, container_name, blob_name)
end

#############################################################################
Azure.configure do |config|
  # Configure these 2 properties to use Storage
  config.storage_account_name = storage_account
  config.storage_access_key   = account_key
end

container_name = "test-container"
pdf_name='programming-ruby.pdf'
pdf_blob_name='write-pdf'

# Create an azure storage blob service object
bs = Azure::BlobService.new

blob_test(bs, container_name, pdf_name, pdf_blob_name)