Ruby – 使用雾在现有s3文件的末尾附加内容

require 'fog'
file    = "abc.csv"
bucket  = 'my_bucket'
storage = Fog::Storage.new(:provider => 'AWS',:aws_access_key_id => 'XXXXXXXX',:aws_secret_access_key => 'YYYYYYYY')
dir     = connection.directories.new(:key => bucket) # no harm,if this bucket already exists,if not create one
buffer  = ["big_chunk1","big_chunk2","big_chunk3","big_chunk4","big_chunk5"]

# I need help after this line. No changes above.
buffer.each do |chunk|
  # this will not work as it will not append text below the existing file or 
  # newly created one. I am not looking for solution suggesting,buffer.join('') 
  # and then write whole chunk at once. I have to write in chuck for some specific reason.
  # Also I dont want to first read existing data and then take in to memory
  # and then append and finally write back.
  dir.files.create(:key => file,:body => chunk,:public => false) 
end