/Chef 12


A knife.rb file is used to specify the chef-repo-specific configuration details for knife.

A knife.rb file:

  • Is loaded every time this executable is run
  • Is not created by default
  • Is located by default at ~/chef-repo/.chef/knife.rb (UNIX and Linux platforms) or c:\Users\username\.chef (Microsoft Windows platform, starting with Chef development kit version 0.7.0); use the --config option from the command line to change this location
  • Will override the default configuration when a knife.rb file exists at the default path or the path specified by the --config option


When running Microsoft Windows, the knife.rb file is located at %HOMEDRIVE%:%HOMEPATH%\chef-repo\.chef (e.g. c:\Users\<username>\chef-repo\.chef). If this path needs to be scripted, use %USERPROFILE%\chef-repo\.chef.


This configuration file has the following settings:

The path to a template file to be used during a bootstrap operation.

The URL for the Chef server. For example:

chef_server_url 'https://localhost/organizations/ORG_NAME'

Enable chef-zero. This setting requires local_mode to be set to true. Default value: false. For example:

chef_zero.enabled true

The port on which chef-zero is to listen. Default value: 8889. For example:

chef_zero[:port] 8889

The location of the file that contains the client key. Default value: /etc/chef/client.pem. For example:

client_key '/etc/chef/client.pem'
The name of the copyright holder. This option places a copyright notice that contains the name of the copyright holder in each of the pre-created files. If this option is not specified, a copyright name of “COMPANY_NAME” is used instead; it can easily be modified later.
The email address for the individual who maintains the cookbook. This option places an email address in each of the pre-created files. If not specified, an email name of “YOUR_EMAIL” is used instead; this can easily be modified later.
The type of license under which a cookbook is distributed: apachev2, gplv2, gplv3, mit, or none (default). This option places the appropriate license notice in the pre-created files: Apache v2.0 (for apachev2), GPL v2 (for gplv2), GPL v3 (for gplv3), MIT (for mit), or license 'Proprietary - All Rights Reserved (for none). Be aware of the licenses for files inside of a cookbook and be sure to follow any restrictions they describe.

The sub-directory for cookbooks on the chef-client. This value can be a string or an array of file system locations, processed in the specified order. The last cookbook is considered to override local modifications. For example:

cookbook_path [

The minimum required version of data bag encryption. Possible values: 1 or 2. When all of the machines in an organization are running chef-client version 11.6 (or higher), it is recommended that this value be set to 2. For example:

data_bag_encrypt_version 2
Allows OpenSSL to enforce FIPS-validated security during the chef-client run. Set to true to enable FIPS-validated security.

Run the chef-client in local mode. This allows all commands that work against the Chef server to also work against the local chef-repo. For example:

local_mode true

The name of the node. This may be a username with permission to authenticate to the Chef server or it may be the name of the machine from which knife is run. For example:

node_name 'user_name'


node_name 'machine_name'

A comma-separated list of URLs that do not need a proxy. Default value: nil. For example:

no_proxy 'localhost, 10.*, *.example.com, *.dev.example.com'
The amount of time (in seconds) to wait for an SSH connection time out.

Set the verify mode for HTTPS requests.

  • Use :verify_none to do no validation of SSL certificates.
  • Use :verify_peer to do validation of all SSL certificates, including the Chef server connections, S3 connections, and any HTTPS remote_file resource URLs used in the chef-client run. This is the recommended setting.

Depending on how OpenSSL is configured, the ssl_ca_path may need to be specified. Default value: :verify_peer.

All files in a cookbook must contain valid Ruby syntax. Use this setting to specify the location in which knife caches information about files that have been checked for valid Ruby syntax.
Split the Tmux window. Default value: false.

The name of the chef-validator key that is used by the chef-client to access the Chef server during the initial chef-client run. For example:

validation_client_name 'chef-validator'

The location of the file that contains the key used when a chef-client is registered with a Chef server. A validation key is signed using the validation_client_name for authentication. Default value: /etc/chef/validation.pem. For example:

validation_key '/etc/chef/validation.pem'
Verify the SSL certificate on the Chef server. When true, the chef-client always verifies the SSL certificate. When false, the chef-client uses the value of ssl_verify_mode to determine if the SSL certificate requires verification. Default value: false.

Append cookbook versions to cookbooks. Set to false to hide cookbook versions: cookbooks/apache. Set to true to show cookbook versions: cookbooks/apache-1.0.0 and/or cookbooks/apache-1.0.1. When this setting is true, knife download downloads ALL cookbook versions, which can be useful if a full-fidelity backup of data on the Chef server is required. For example:

versioned_cookbooks true

Proxy Settings

In certain situations the proxy used by the Chef server requires authentication. In this situation, three settings must be added to the configuration file. Which settings to add depends on the protocol used to access the Chef server: HTTP or HTTPS.

If the Chef server is configured to use HTTP, add the following settings:


The proxy server for HTTP connections. Default value: nil. For example:

http_proxy 'http://proxy.vmware.com:3128'
The user name for the proxy server when the proxy server is using an HTTP connection. Default value: nil.
The password for the proxy server when the proxy server is using an HTTP connection. Default value: nil.

If the Chef server is configured to use HTTPS (such as the hosted Chef server), add the following settings:

The proxy server for HTTPS connections. (The hosted Chef server uses an HTTPS connection.) Default value: nil.
The user name for the proxy server when the proxy server is using an HTTPS connection. Default value: nil.
The password for the proxy server when the proxy server is using an HTTPS connection. Default value: nil.

Use the following setting to specify URLs that do not need a proxy:

A comma-separated list of URLs that do not need a proxy. Default value: nil.

Optional Settings

In addition to the default settings in a knife.rb file, there are other subcommand-specific settings that can be added. When a subcommand is run, knife will use:

  1. A value passed via the command-line
  2. A value contained in the knife.rb file
  3. The default value

A value passed via the command line will override a value in the knife.rb file; a value in a knife.rb file will override a default value.

Before adding any settings to the knife.rb file:

  • Verify the settings by reviewing the documentation for the knife subcommands and/or knife plugins
  • Verify the use case(s) your organization has for adding them

Also note that:

  • Custom plugins can be configured to use the same settings as the core knife subcommands
  • Many of these settings are used by more than one subcommand and/or plugin
  • Some of the settings are included only because knife checks for a value in the knife.rb file

To add settings to the knife.rb file, use the following syntax:

knife[:setting_name] = value

where value may require quotation marks (‘ ‘) if that value is a string. For example:

knife[:ssh_port] = 22
knife[:bootstrap_template] = 'ubuntu14.04-gems'
knife[:bootstrap_version] = ''
knife[:bootstrap_proxy] = ''

Some of the optional knife.rb settings are used often, such as the template file used in a bootstrap operation. The frequency of use of any option varies from organization to organization, so even though the following settings are often added to a knife.rb file, they may not be the right settings to add for every organization:

The proxy server for the node that is the target of a bootstrap operation.
The path to a template file to be used during a bootstrap operation.
The version of the chef-client to install.
The $EDITOR that is used for all interactive commands.
The SSH tunnel or gateway that is used to run a bootstrap action on a machine that is not accessible from the workstation. Adding this setting can be helpful when a user cannot SSH directly into a host.
The SSH port.

Other SSH-related settings that are sometimes helpful when added to the knife.rb file:

Enable SSH agent forwarding.
The attribute used when opening an SSH connection.
The SSH password. This can be used to pass the password directly on the command line. If this option is not specified (and a password is required) knife prompts for the password.
The SSH user name.

Some organizations choose to have all data bags use the same secret and secret file, rather than have a unique secret and secret file for each data bag. To use the same secret and secret file for all data bags, add the following to knife.rb:

The encryption key that is used for values contained within a data bag item.
The path to the file that contains the encryption key.

Some settings are better left to Ohai, which will get the value at the start of the chef-client run:

Same as node_name. Recommended configuration is to allow Ohai to collect this value during each chef-client run.
See the description above for this setting.

When working with chef-container, add the following setting:

The path to the directory in which Docker contexts are stored. Default value: /var/chef/dockerfiles.


Review the full list of optional settings that can be added to the knife.rb file. Many of these optional settings should not be added to the knife.rb file. The reasons for not adding them can vary. For example, using --yes as a default in the knife.rb file will cause knife to always assume that “Y” is the response to any prompt, which may lead to undesirable outcomes. Other settings, such as --hide-healthy (used only with the knife status subcommand) or --bare-directories (used only with the knife list subcommand) probably aren’t used often enough (and in the same exact way) to justify adding them to the knife.rb file. In general, if the optional settings are not listed on the main knife.rb topic, then add settings only after careful consideration. Do not use optional settings in a production environment until after the setting’s performance has been validated in a safe testing environment.

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           "[email protected]"

  # 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']

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