cookbook_file Resource

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Use the cookbook_file resource to transfer files from a sub-directory of COOKBOOK_NAME/files/ to a specified path located on a host that’s running Chef Infra Client. The file is selected according to file specificity, which allows different source files to be used based on the hostname, host platform (operating system, distro, or as appropriate), or platform version. Files that are located in the COOKBOOK_NAME/files/default sub-directory may be used on any platform.

During a Chef Infra Client run, the checksum for each local file is calculated and then compared against the checksum for the same file as it currently exists in the cookbook on the Chef Infra Server. A file isn’t transferred when the checksums match. Only files that require an update are transferred from the Chef Infra Server to a node.

Syntax

A cookbook_file resource block manages files by using files that exist within a cookbook’s /files directory. For example, to write the home page for an Apache website:

cookbook_file '/var/www/customers/public_html/index.php' do
  source 'index.php'
  owner 'web_admin'
  group 'web_admin'
  mode '0755'
  action :create
end

where:

• '/var/www/customers/public_html/index.php' is path to the file to be created
• 'index.php' is a file in the /files directory in a cookbook that is used to create that file (the contents of the file in the cookbook will become the contents of the file on the node)
• owner, group, and mode define the permissions

The full syntax for all of the properties that are available to the cookbook_file resource is:

cookbook_file 'name' do
  atomic_update              true, false
  backup                     Integer, false # default value: 5
  cookbook                   String
  force_unlink               true, false # default value: false
  group                      String, Integer
  inherits                   true, false
  manage_symlink_source      true, false
  mode                       String, Integer
  owner                      String, Integer
  path                       String # default value: 'name' unless specified
  rights                     Hash
  source                     String, Array
  verify                     String, Block
  action                     Symbol # defaults to :create if not specified
end

where:

• cookbook_file is the resource.
• name is the name given to the resource block.
• action identifies which steps Chef Infra Client will take to bring the node into the desired state.
• atomic_update, backup, checksum, content, cookbook, deny_rights, force_unlink, manage_symlink_source, path, rights, and source are the properties available to this resource.

Actions

The cookbook_file resource has the following actions:

:create

(default) Create a file. If a file already exists (but does not match), update that file to match.

:create_if_missing

Create a file only if the file does not exist. When the file exists, nothing happens.

:delete

Delete a file.

:nothing

This resource block doesn’t act unless notified by another resource to take action. Once notified, this resource block either runs immediately or is queued up to run at the end of a Chef Infra Client run.

:touch

Touch a file. This updates the access (atime) and file modification

Properties

The cookbook_file resource has the following properties:

atomic_update

Ruby Type: true, false | Default Value: False if modifying /etc/hosts, /etc/hostname, or /etc/resolv.conf within Docker containers. Otherwise default to the client.rb 'file_atomic_update' config value.

Perform atomic file updates on a per-resource basis. Set to true for atomic file updates. Set to false for non-atomic file updates. This setting overrides file_atomic_update, which is a global setting found in the client.rb file.

backup

Ruby Type: Integer, false | Default Value: 5

The number of backups to be kept in /var/chef/backup (for UNIX- and Linux-based platforms) or C:/chef/backup (for the Microsoft Windows platform). Set to false to prevent backups from being kept.

cookbook

Ruby Type: String | Default Value: The current cookbook name

The cookbook in which a file is located (if it is not located in the current cookbook).

force_unlink

Ruby Type: true, false | Default Value: false

How Chef Infra Client handles certain situations when the target file turns out not to be a file. For example, when a target file is actually a symlink. Set to true for Chef Infra Client to delete the non-file target and replace it with the specified file. Set to false for Chef Infra Client to raise an error.

group

Ruby Type: Integer, String

A string or ID that identifies the group owner by group name or SID, including fully qualified group names such as domain\group or group@domain. If this value is not specified, existing groups remain unchanged and new group assignments use the default POSIX group (if available).

inherits

Ruby Type: true, false | Default Value: true

Microsoft Windows only. Whether a file inherits rights from its parent directory.

manage_symlink_source

Ruby Type: true, false | Default Value: true

(with warning) Change the behavior of the file resource if it is pointed at a symlink. When this value is set to true, Chef Infra Client will manage the symlink’s permissions or will replace the symlink with a normal file if the resource has content. When this value is set to false, Chef Infra Client will follow the symlink and will manage the permissions and content of symlink’s target file. The default behavior is true, but emits a warning that the default value will be changed to false in a future version; setting this explicitly to true or false suppresses this warning.

mode

Ruby Type: Integer, String

If mode is not specified and if the file already exists, the existing mode on the file is used. If mode is not specified, the file does not exist, and the :create action is specified, Chef Infra Client assumes a mask value of '0777' and then applies the umask for the system on which the file is to be created to the mask value. For example, if the umask on a system is '022', Chef Infra Client uses the default value of '0755'.

The behavior is different depending on the platform.

UNIX- and Linux-based systems: A quoted 3-5 character string that defines the octal mode that is passed to chmod. For example: '755', '0755', or 00755. If the value is specified as a quoted string, it works exactly as if the chmod command was passed. If the value is specified as an integer, prepend a zero (0) to the value to ensure that it is interpreted as an octal number. For example, to assign read, write, and execute rights for all users, use '0777' or '777'; for the same rights, plus the sticky bit, use 01777 or '1777'.

Microsoft Windows: A quoted 3-5 character string that defines the octal mode that is translated into rights for Microsoft Windows security. For example: '755', '0755', or 00755. Values up to '0777' are allowed (no sticky bits) and mean the same in Microsoft Windows as they do in UNIX, where 4 equals GENERIC_READ, 2 equals GENERIC_WRITE, and 1 equals GENERIC_EXECUTE. This property cannot be used to set :full_control. This property has no effect if not specified, but when it and rights are both specified, the effects are cumulative.

owner

Ruby Type: Integer, String

A string or ID that identifies the group owner by user name or SID, including fully qualified user names such as domain\user or user@domain. If this value is not specified, existing owners remain unchanged and new owner assignments use the current user (when necessary).

path

Ruby Type: String | Default Value: The resource block's name

The full path to the file, including the file name and its extension. For example: /files/file.txt. Default value: the name of the resource block. Microsoft Windows: A path that begins with a forward slash / will point to the root of the current working directory of the Chef Infra Client process. This path can vary from system to system. Therefore, using a path that begins with a forward slash / is not recommended.

rights

Ruby Type: Integer, String

Microsoft Windows only. The permissions for users and groups in a Microsoft Windows environment. For example: rights <permissions>, <principal>, <options> where <permissions> specifies the rights granted to the principal, <principal> is the group or user name, and <options> is a Hash with one (or more) advanced rights options.

source

Ruby Type: String, Array | Default Value: The resource block's name.

The name of the file in COOKBOOK_NAME/files/default or the path to a file located in COOKBOOK_NAME/files. The path must include the file name and its extension. This can be used to distribute specific files depending upon files depending upon the platform used - see File Specificity for more information.'

verify

Ruby Type: String, Block

A block or a string that returns true or false. A string, when true is executed as a system command.

A block is arbitrary Ruby defined within the resource block by using the verify property. When a block is true, Chef Infra Client will continue to update the file as appropriate.

For example, this should return true:

cookbook_file '/tmp/baz' do
  verify { 1 == 1 }
end

This should return true:

cookbook_file '/etc/nginx.conf' do
  verify 'nginx -t -c %{path}'
end

This should return true:

cookbook_file '/tmp/bar' do
  verify { 1 == 1}
end

And this should return true:

cookbook_file '/tmp/foo' do
  verify do |path|
    true
  end
end

Whereas, this should return false:

cookbook_file '/tmp/turtle' do
  verify '/usr/bin/false'
end

If a string or a block return false, the Chef Infra Client run will stop and an error is returned.

Atomic File Updates

Atomic updates are used with file-based resources to help ensure that file updates can be made when updating a binary or if disk space runs out.

Atomic updates are enabled by default. They can be managed globally using the file_atomic_update setting in the client.rb file. They can be managed for each resource using the atomic_update property that’s available with the cookbook_file, file, remote_file, and template resources.

Windows File Security

The rights property can be used in a recipe to manage access control lists (ACLs), which allow permissions to be given to multiple users and groups. Use the rights property can be used as many times as necessary; Chef Infra Client will apply them to the file or directory as required. The syntax for the rights property is as follows:

rights permission, principal, option_type => value

where

permission

Use to specify which rights are granted to the principal. The possible values are: :read, :write, read_execute, :modify, :full_control, or an integer.

Integers used for permissions must match the following list FileSystemRights Enum fields.

These permissions are cumulative. If :write is specified, then it includes :read. If :full_control is specified, then it includes both :write and :read.

(For those who know the Windows API: :read corresponds to GENERIC_READ; :write corresponds to GENERIC_WRITE; :read_execute corresponds to GENERIC_READ and GENERIC_EXECUTE; :modify corresponds to GENERIC_WRITE, GENERIC_READ, GENERIC_EXECUTE, and DELETE; :full_control corresponds to GENERIC_ALL, which allows a user to change the owner and other metadata about a file.)

principal

Use to specify a group or user. The principal can be specified by either name or SID. When using name, this is identical to what’s entered in the login box for Windows, such as user_name, domain\user_name, or user_name@fully_qualified_domain_name. When using a SID, you may use either the standard string representation of a SID (S-R-I-S-S) or one of the SDDL string constants. Chef Infra Client doesn’t need to know if a principal is a user or a group.

option_type

A hash that contains advanced rights options. For example, the rights to a directory that only applies to the first level of children might look something like: rights :write, 'domain\group_name', :one_level_deep => true.

Possible option types:

:applies_to_children

Specify how permissions are applied to children. Possible values: true to inherit both child directories and files; false to not inherit any child directories or files; :containers_only to inherit only child directories (and not files); :objects_only to recursively inherit files (and not child directories).

:applies_to_self

Indicates whether a permission is applied to the parent directory. Possible values: true to apply to the parent directory or file and its children; false to not apply only to child directories and files.

:one_level_deep

Indicates the depth to which permissions will be applied. Possible values: true to apply only to the first level of children; false to apply to all children.

For example:

resource 'x.txt' do
  rights :read, 'S-1-1-0'
  rights :write, 'domain\group'
  rights :full_control, 'group_name_or_user_name'
  rights :full_control, 'user_name', applies_to_children: true
end

or:

rights :read, %w(Administrators Everyone)
rights :full_control, 'Users', applies_to_children: true
rights :write, 'Sally', applies_to_children: :containers_only, applies_to_self: false, one_level_deep: true

Some other important things to know when using the rights attribute:

• Only inherited rights remain. All existing explicit rights on the object are removed and replaced.
• If rights aren’t specified, nothing will be changed. Chef Infra Client doesn’t clear out the rights on a file or directory if rights aren’t specified.
• Changing inherited rights can be expensive. Windows will propagate rights to all children recursively due to inheritance. This is a normal aspect of Windows, so consider the frequency with which this type of action is necessary and take steps to control this type of action if performance is the primary consideration.

Use the deny_rights property to deny specific rights to specific users. The ordering is independent of using the rights property. For example, it doesn’t matter if rights are granted to everyone is placed before or after deny_rights :read, ['Julian', 'Lewis'], both Julian and Lewis will be unable to read the document. For example:

resource 'x.txt' do
  rights :read, 'Everyone'
  rights :write, 'domain\group'
  rights :full_control, 'group_name_or_user_name'
  rights :full_control, 'user_name', applies_to_children: true
  deny_rights :read, %w(Julian Lewis)
end

or:

deny_rights :full_control, ['Sally']

By default, a file or directory inherits rights from its parent directory. Most of the time this is the preferred behavior, but sometimes it may be necessary to take steps to more specifically control rights. The inherits property can be used to specifically tell Chef Infra Client to apply (or not apply) inherited rights from its parent directory.

For example, the following example specifies the rights for a directory:

directory 'C:\mordor' do
  rights :read, 'MORDOR\Minions'
  rights :full_control, 'MORDOR\Sauron'
end

and then the following example specifies how to use inheritance to deny access to the child directory:

directory 'C:\mordor\mount_doom' do
  rights :full_control, 'MORDOR\Sauron'
  inherits false # Sauron is the only person who should have any sort of access
end

If the deny_rights permission were to be used instead, something could slip through unless all users and groups were denied.

Another example also shows how to specify rights for a directory:

directory 'C:\mordor' do
  rights :read, 'MORDOR\Minions'
  rights :full_control, 'MORDOR\Sauron'
  rights :write, 'SHIRE\Frodo' # Who put that there I didn't put that there
end

but then not use the inherits property to deny those rights on a child directory:

directory 'C:\mordor\mount_doom' do
  deny_rights :read, 'MORDOR\Minions' # Oops, not specific enough
end

Because the inherits property isn’t specified, Chef Infra Client will default it to true, which will ensure that security settings for existing files remain unchanged.

Common Resource Functionality

Chef resources include common properties, notifications, and resource guards.

Common Properties

The following properties are common to every resource:

compile_time

Ruby Type: true, false | Default Value: false

Control the phase during which the resource is run on the node. Set to true to run while the resource collection is being built (the compile phase). Set to false to run while Chef Infra Client is configuring the node (the converge phase).

ignore_failure

Ruby Type: true, false, :quiet | Default Value: false

Continue running a recipe if a resource fails for any reason. :quiet won’t display the full stack trace and the recipe will continue to run if a resource fails.

retries

Ruby Type: Integer | Default Value: 0

The number of attempts to catch exceptions and retry the resource.

retry_delay

Ruby Type: Integer | Default Value: 2

The delay in seconds between retry attempts.

sensitive

Ruby Type: true, false | Default Value: false

Ensure that sensitive resource data isn’t logged by Chef Infra Client.

Notifications

notifies

Ruby Type: Symbol, 'Chef::Resource[String]'

A resource may notify another resource to take action when its state changes. Specify a 'resource[name]', the :action that resource should take, and then the :timer for that action. A resource may notify more than one resource; use a notifies statement for each resource to be notified.

If the referenced resource doesn’t exist, an error is raised. In contrast, subscribes won’t fail if the source resource isn’t found.

A timer specifies the point during a Chef Infra Client run at which a notification is run. The following timers are available:

:before

Specifies that the action on a notified resource should be run before processing the resource block in which the notification is located.

:delayed

Default. Specifies that a notification should be queued up, and then executed at the end of a Chef Infra Client run.

:immediate, :immediately

Specifies that a notification should be run immediately, for each resource notified.

The syntax for notifies is:

notifies :action, 'resource[name]', :timer

subscribes

Ruby Type: Symbol, 'Chef::Resource[String]'

A resource may listen to another resource, and then take action if the state of the resource being listened to changes. Specify a 'resource[name]', the :action to be taken, and then the :timer for that action.

Note that subscribes doesn’t apply the specified action to the resource that it listens to - for example:

file '/etc/nginx/ssl/example.crt' do
  mode '0600'
  owner 'root'
end

service 'nginx' do
  subscribes :reload, 'file[/etc/nginx/ssl/example.crt]', :immediately
end

In this case the subscribes property reloads the nginx service whenever its certificate file, located under /etc/nginx/ssl/example.crt, is updated. subscribes doesn’t make any changes to the certificate file itself, it merely listens for a change to the file, and executes the :reload action for its resource (in this example nginx) when a change is detected.

If the other resource doesn’t exist, the subscription won’t raise an error. Contrast this with the stricter semantics of notifies, which will raise an error if the other resource doesn’t exist.

A timer specifies the point during a Chef Infra Client run at which a notification is run. The following timers are available:

:before

Specifies that the action on a notified resource should be run before processing the resource block in which the notification is located.

:delayed

Default. Specifies that a notification should be queued up, and then executed at the end of a Chef Infra Client run.

:immediate, :immediately

Specifies that a notification should be run immediately, for each resource notified.

The syntax for subscribes is:

subscribes :action, 'resource[name]', :timer

Guards

A guard property can be used to evaluate the state of a node during the execution phase of a Chef Infra Client run. Based on the results of this evaluation, a guard property is then used to tell Chef Infra Client if it should continue executing a resource. A guard property accepts either a string value or a Ruby block value:

• A string is executed as a shell command. If the command returns 0, the guard is applied. If the command returns any other value, then the guard property isn’t applied. String guards in a powershell_script run Windows PowerShell commands and may return true in addition to 0.
• A block is executed as Ruby code that must return either true or false. If the block returns true, the guard property is applied. If the block returns false, the guard property isn’t applied.

A guard property is useful for ensuring that a resource is idempotent by allowing that resource to test for the desired state as it’s being executed, and then if the desired state is present, for Chef Infra Client to don’thing.

The following properties can be used to define a guard that’s evaluated during the execution phase of a Chef Infra Client run:

not_if

Prevent a resource from executing when the condition returns true.

only_if

Allow a resource to execute only if the condition returns true.

File Specificity

A cookbook is frequently designed to work across many platforms and is often required to distribute a specific file to a specific platform. A cookbook can be designed to support the distribution of files across platforms, while ensuring that the correct file ends up on each system.

The pattern for file specificity depends on two things: the lookup path and the source attribute. The first pattern that matches is used:

1. /host-\$fqdn/\$source
2. /\$platform-\$platform_version/\$source
3. /\$platform/\$source
4. /default/\$source
5. /\$source

Use an array with the source attribute to define an explicit lookup path. For example:

file '/conf.py' do
  source ['#{node.chef_environment}.py', 'conf.py']
end

The following example emulates the entire file specificity pattern by defining it as an explicit path:

file '/conf.py' do
  source %W(
    host-#{node['fqdn']}/conf.py
    #{node['platform']}-#{node['platform_version']}/conf.py
    #{node['platform']}/conf.py
    default/conf.py
  )
end

A cookbook may have a /files directory structure like this:

files/
    host-foo.example.com
    ubuntu-20.04
    ubuntu-20
    ubuntu
    redhat-8.2
    redhat-7.8
    ...
    default

and a resource that looks something like the following:

cookbook_file '/usr/local/bin/apache2_module_conf_generate.pl' do
  source 'apache2_module_conf_generate.pl'
  mode '0755'
  owner 'root'
  group 'root'
end

This resource is matched in the same order as the /files directory structure. For a node that’s running Ubuntu 20.04, the second item would be the matching item and the location to which the file identified in the cookbook_file resource would be distributed:

host-foo.example.com/apache2_module_conf_generate.pl
ubuntu-20.04/apache2_module_conf_generate.pl
ubuntu-20/apache2_module_conf_generate.pl
ubuntu/apache2_module_conf_generate.pl
default/apache2_module_conf_generate.pl

If the apache2_module_conf_generate.pl file was located in the cookbook directory under files/host-foo.example.com/, the specified files would only be copied to the machine with the domain name foo.example.com.

Host Notation

The naming of folders within cookbook directories must literally match the host notation used for file specificity matching. For example, if a host is named foo.example.com, the folder must be named host-foo.example.com.

Examples

The following examples demonstrate various approaches for using the cookbook_file resource in recipes:

Transfer a file

cookbook_file 'file.txt' do
  mode '0755'
end

Handle cookbook_file and package resources in the same recipe

When a cookbook_file resource and a package resource are both called from within the same recipe, use the flush_cache attribute to dump the in-memory Yum cache, and then use the repository immediately to ensure that the correct package is installed:

cookbook_file '/etc/yum.repos.d/custom.repo' do
  source 'custom'
  mode '0755'
end

package 'only-in-custom-repo' do
  action :install
  flush_cache [ :before ]
end

Install repositories from a file, trigger a command, and force the internal cache to reload

The following example shows how to install new Yum repositories from a file, where the installation of the repository triggers a creation of the Yum cache that forces the internal cache for Chef Infra Client to reload:

execute 'create-yum-cache' do
 command 'yum -q makecache'
 action :nothing
end

ruby_block 'reload-internal-yum-cache' do
  block do
    Chef::Provider::Package::Yum::YumCache.instance.reload
  end
  action :nothing
end

cookbook_file '/etc/yum.repos.d/custom.repo' do
  source 'custom'
  mode '0755'
  notifies :run, 'execute[create-yum-cache]', :immediately
  notifies :create, 'ruby_block[reload-internal-yum-cache]', :immediately
end

Use a case statement

The following example shows how a case statement can be used to handle a situation where an application needs to be installed on multiple platforms, but where the install directories are different paths, depending on the platform:

cookbook_file 'application.pm' do
  path case node['platform']
    when 'centos','redhat'
      '/usr/lib/version/1.2.3/dir/application.pm'
    when 'arch'
      '/usr/share/version/core_version/dir/application.pm'
    else
      '/etc/version/dir/application.pm'
    end
  source "application-#{node['languages']['perl']['version']}.pm"
  owner 'root'
  group 'root'
  mode '0755'
end

Manage dotfiles

The following example shows using the directory and cookbook_file resources to manage dotfiles. The dotfiles are defined by a JSON data structure similar to:

"files": {
  ".zshrc": {
    "mode": '0755',
    "source": "dot-zshrc"
    },
  ".bashrc": {
    "mode": '0755',
    "source": "dot-bashrc"
     },
  ".bash_profile": {
    "mode": '0755',
    "source": "dot-bash_profile"
    },
  }

and then the following resources manage the dotfiles:

if u.has_key?('files')
  u['files'].each do |filename, file_data|

  directory "#{home_dir}/#{File.dirname(filename)}" do
    recursive true
    mode '0755'
  end if file_data['subdir']

  cookbook_file "#{home_dir}/#{filename}" do
    source "#{u['id']}/#{file_data['source']}"
    owner 'u['id']'
    group 'group_id'
    mode 'file_data['mode']'
    ignore_failure true
    backup 0
  end
end