gistfile1.txt

master ✗ % cat short_monsters 
baku
bugbear
curst
dryad
floater
goblyn
hobgoblin
khargra
magen
murderoid
parasite
razorvine
shadowperson
squealer
tressym
wemic

master ✗ % cat monster.rb 
File.foreach('short_monsters') do |monster|
  item = {
    "id" => monster,
    "status" => "available"
  }
  databag_item = Chef::DataBagItem.new
  databag_item.data_bag("hostnames")
  databag_item.raw_data = item
  databag_item.save
end

master ✗ % knife exec monster.rb                                                                                                                                 1 ↵

master ✗ % knife data bag show hostnames
[
  "baku",
  "bugbear",
  "curst",
  "dryad",
  "floater",
  "goblyn",
  "hobgoblin",
  "khargra",
  "magen",
  "monsters",
  "murderoid",
  "parasite",
  "razorvine",
  "shadowperson",
  "squealer",
  "tressym",
  "wemic"
]

master ✗ % knife data bag show hostnames baku
{
  "id": "baku",
  "status": "available"
}

% knife exec -E "puts search(:hostnames, 'NOT status:TAKEN').map { |a| a['id']}.choice"
murderoid
master ✗ % knife exec -E "puts search(:hostnames, 'NOT status:TAKEN').map { |a| a['id']}.choice"
goblyn