Working with Knife

knife runs from a management workstation and sits in-between a Chef server and an organization’s infrastructure. knife interacts with a Chef server by using the same REST API that is used by a chef-client. Role-based authentication controls (RBAC) can be used to authorize changes when knife is run with the Chef server. knife is configured during workstation setup, but subsequent modifications can be made using the knife.rb configuration file.

JSON Data Format

Most data is entered using a text editor in JSON format, unless the --disable-editing option is entered as part of a command. (Encrypted data bags use YAML, which is a superset of JSON.) JSON is a common, language-independent data format that provides a simple text representation of arbitrary data structures. For more information about JSON, see http://www.json.org/ or http://en.wikipedia.org/wiki/JSON.

Using Quotes

Values can be entered with double quotes (” ”) or single quotes (‘ ‘), but this should be done consistently.

Subcommands

knife comes with a collection of built in subcommands that work together to provide all of the functionality required to take specific actions against any object in an organization, including cookbooks, nodes, roles, data bags, environments, and users. A knife plugin extends the functionality beyond built-in subcommands.

knife has the following subcommands: bootstrap, client, configure, cookbook, cookbook site, data bag, delete, deps, diff, download, edit, environment, exec, index rebuild, list, node, recipe list, role, search, show, ssh, status, tag, upload, user, and xargs.

Note

The following subcommands run only against the open source Chef server: index rebuild and user.

Verb Subcommands

knife includes a set of subcommands that are built around common verbs: create, delete, download, list, show, and upload. These subcommands allow knife to issue commands that interact with any object stored in the chef-repo or stored on the Chef server. Some important principles behind this group of subcommands includes:

  • A command that works with each object in the chef-repo. The subcommands specify the desired action (the “verb”), and then directory in which that object resides (cookbooks/, data_bags/, environments/, and roles/). For example: download cookbooks/
  • Uses the Chef server as if it were a file system, allowing the chef-repo on the Chef server to behave like a mirror of the chef-repo on the workstation. The Chef server will have the same objects as the local chef-repo. To make changes to the files on the Chef server, just download files from the Chef server or upload files from the chef-repo
  • The context from which a command is run matters. For example, when working in the /roles directory, knife will know what is being worked with. Enter knife show base.json and knife will return the base role from the Chef server. From the chef-repo root, enter knife show roles/base.json to get the same result

Plug-ins

Chef provides the following plugins, which work the same as built-in subcommands (including common options), but must be installed separately (using RubyGems): knife azure, knife bluebox, knife ec2, knife eucalyptus, knife google, knife linode, knife openstack, knife rackspace, knife terremark, knife vcloud, and knife windows.

The community provides many other plugins for knife: http://community.opscode.com/.

Syntax

All knife subcommands have the following syntax:

knife subcommand [ARGUMENT] (options)

Each subcommand has its own set of arguments and options.

Note

All syntax examples in this document show variables in ALL_CAPS. For example -u PORT_LIST (where PORT_LIST is a comma-separated list of local and public UDP ports) or -F FORMAT (where FORMAT determines the output format, either summary, text, json, yaml, or pp). These variables often require specific values that are unique to each organization.

Many Users, Same Repo

It is possible for multiple users to access the Chef server using the same knife.rb file. (A user can even access multiple organizations if, for example, each instance of the chef-repo contained the same copy of the knife.rb file.) This can be done by adding the knife.rb file to the chef-repo, and then using environment variables to handle the user-specific credential details and/or sensitive values. For example:

current_dir = File.dirname(__FILE__)
  user = ENV['OPSCODE_USER'] || ENV['USER']
  node_name                user
  client_key               "#{ENV['HOME']}/chef-repo/.chef/#{user}.pem"
  validation_client_name   "#{ENV['ORGNAME']}-validator"
  validation_key           "#{ENV['HOME']}/chef-repo/.chef/#{ENV['ORGNAME']}-validator.pem"
  chef_server_url          "https://api.opscode.com/organizations/#{ENV['ORGNAME']}"
  syntax_check_cache_path  "#{ENV['HOME']}/chef-repo/.chef/syntax_check_cache"
  cookbook_path            ["#{current_dir}/../cookbooks"]
  cookbook_copyright       "Your Company, Inc."
  cookbook_license         "apachev2"
  cookbook_email           "cookbooks@yourcompany.com"

  # Amazon AWS
  knife[:aws_access_key_id] = ENV['AWS_ACCESS_KEY_ID']
  knife[:aws_secret_access_key] = ENV['AWS_SECRET_ACCESS_KEY']

  # Rackspace Cloud
  knife[:rackspace_api_username] = ENV['RACKSPACE_USERNAME']
  knife[:rackspace_api_key] = ENV['RACKSPACE_API_KEY']