A data bag is a global variable that's stored as JSON data and is accessible from a Chef server or chef-solo. A Chef server indexes a data bag, and hence it can be searched using Chef API. Recipes can also search a data bag and access its items.

A data bag has the following structure:

{
  "id": "item_name",
   "key_1": "value_1",
    . . .
    "key_n": "value_n"
}

Before an item can be uploaded to a data bag, a directory structure needs to be put in place to store the JSON files. In chef-repo, create a directory structure as follows:

chef-repo
|-- cookbooks
|-- data_bags
|-- environments
'-- roles

All the data bags will get stored in the data_bags directory. Let's say we've a data bag called users that will be used to store information such as the name, SSH key, and home directory of different users. This will require us to create a directory structure as follows:

chef-repo/data_bags
|-- users

All the JSON files corresponding to different users will go inside this directory.