The simplest libgfapi example Ruby FFI version.

hellogluster.rb

require 'ffi'

module GLFS
  extend FFI::Library
  ffi_lib 'gfapi'
  attach_function :new, :glfs_new, [:string], :pointer
  attach_function :set_volfile_server, :glfs_set_volfile_server,
    [:pointer, :string, :string, :int], :int
  attach_function :init, :glfs_init, [:pointer], :int
  attach_function :creat, :glfs_creat, [:pointer, :string, :int, :int], :pointer
  attach_function :write, :glfs_write, [:pointer, :string, :uint, :int], :uint
  attach_function :close, :glfs_close, [:pointer], :int
end

fs = GLFS.new 'volume_name'
ret = GLFS.set_volfile_server fs, 'tcp', 'server_address', 24007
ret = GLFS.init fs
fd = GLFS.creat fs, 'filename', 2, 0644
s = "hello gluster\n"
ret = GLFS.write fd, s, s.size+1, 0
GLFS.close fd