file Resource

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Use the file resource to manage files directly on a node.

Note

Use the cookbook_file resource to copy a file from a cookbook’s /files directory. Use the template resource to create a file based on a template in a cookbook’s /templates directory. And use the remote_file resource to transfer a file to a node from a remote location.

Syntax

A file resource block manages files that exist on nodes. For example, to write the home page for an Apache website:

file '/var/www/customers/public_html/index.php' do
  content '<html>This is a placeholder for the home page.</html>'
  mode '0755'
  owner 'web_admin'
  group 'web_admin'
end

where:

'/var/www/customers/public_html/index.php' is path to the file and also the filename to be managed
content defines the contents of the file

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

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

where:

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, force_unlink, group, inherits, manage_symlink_source, mode, owner, path, rights, and verify are properties of this resource, with the Ruby type shown.

Actions

The 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 does not 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 (mtime) times for a file.

Properties

The 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.

checksum

Ruby Type: String

The SHA-256 checksum of the file. Use to ensure that a specific file is used. If the checksum does not match, the file is not used.

content

Ruby Type: String

A string that is written to the file. The contents of this property replace any previous content when this property has something other than the default value. The default behavior will not modify content.

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

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

A quoted 3-5 character string that defines the octal mode. For example: '755', '0755', or 00755.

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.

verify

Ruby Type: String, Block, Symbol

Allows verification of a file’s contents before it is created. Creates a temporary file and then allows execution of commands or Ruby code. If this code evaluates to true, the file is created. If the code evaluates to false, an error is raised.

The types for this property are a block, string, or a symbol. When specified as a block, it returns true or false. When specified as a string, it is executed as a system command. It returns true if the command returns 0 as its exit status code and false if the command returns a non-zero exit status code. When using a built-in verifier symbol it returns true if the verifier succeeds else it returns false.

Currently suppported verifiers are :yaml, :json and :systemd_unit.

Note

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

For example, this should return true:

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

This should also return true:

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

In this example, the %{path} portion of this command is expanded to the temporary location where a copy of the file to be created exists. This will use Nginx’s syntax checking feature to ensure the file is a valid Nginx configuration file before writing the file. An error will be raised if the executed command returns a non-zero exit status code.

This should return true:

file '/tmp/foo' do
  content "hello"
  verify do |path|
    open(path).read.include?       "hello"
  end
end

Whereas, this should return false:

file '/tmp/foo' do
  content "goodbye"
  verify do |path|
    open(path).read.include?       "hello"
  end
end

When using one of the built-in symbols(:json, :yaml, :systemd_unit)

This should return true:

file 'foo.json' do
  content '{"foo": "bar"}'
  verify :json
end

Whereas, this should return false:

file 'foo.yaml' do
    content "--- foo: 'foo-"
    verify :yaml
end

If a string, block or symbol returns false, the Chef Infra Client run will stop and an error is raised.

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 is available with the cookbook_file, file, remote_file, and template resources.

Note

On certain platforms, and after a file has been moved into place, Chef Infra Client may modify file permissions to support features specific to those platforms. On platforms with SELinux enabled, Chef Infra Client will fix up the security contexts after a file has been moved into the correct location by running the restorecon command. On the Microsoft Windows platform, Chef Infra Client will create files so that ACL inheritance works as expected.

Windows File Security

To support Windows security, the template, file, remote_file, cookbook_file, directory, and remote_directory resources support the use of inheritance and access control lists (ACLs) within recipes. Access Control Lists (ACLs)

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 is 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 does not 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 are not specified, nothing will be changed. Chef Infra Client does not clear out the rights on a file or directory if rights are not 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']

Inheritance

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 is not 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 will not 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 is not 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 does not exist, an error is raised. In contrast, subscribes will not fail if the source resource is not 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 does not 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 does not 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 does not exist, the subscription will not raise an error. Contrast this with the stricter semantics of notifies, which will raise an error if the other resource does not 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 is not 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 is not 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 is being executed, and then if the desired state is present, for Chef Infra Client to do nothing.

Properties

The following properties can be used to define a guard that is 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.

Examples

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

Create a file

file '/tmp/something' do
  owner 'root'
  group 'root'
  mode '0755'
  action :create
end

Create a file in Microsoft Windows

To create a file in Microsoft Windows, be sure to add an escape character—\—before the backslashes in the paths:

file 'C:\\tmp\\something.txt' do
  rights :read, 'Everyone'
  rights :full_control, 'DOMAIN\\User'
  action :create
end

Remove a file

file '/tmp/something' do
  action :delete
end

Set file modes

file '/tmp/something' do
  mode '0755'
end

Delete a repository using yum to scrub the cache

# the following code sample thanks to gaffneyc @ https://gist.github.com/918711

execute 'clean-yum-cache' do
  command 'yum clean all'
  action :nothing
end

file '/etc/yum.repos.d/bad.repo' do
  action :delete
  notifies :run, 'execute[clean-yum-cache]', :immediately
  notifies :create, 'ruby_block[reload-internal-yum-cache]', :immediately
end

Add the value of a data bag item to a file

The following example shows how to get the contents of a data bag item named impossible_things, create a .pem file located at some/directory/path/, and then use the content attribute to update the contents of that file with the value of the impossible_things data bag item:

private_key = data_bag_item('impossible_things', private_key_name)['private_key']

file "some/directory/path/#{private_key_name}.pem" do
  content private_key
  owner 'root'
  group 'group'
  mode '0755'
end

Write a YAML file

The following example shows how to use the content property to write a YAML file:

file "#{app['deploy_to']}/shared/config/settings.yml" do
  owner "app['owner']"
  group "app['group']"
  mode '0755'
  content app.to_yaml
end

Write a string to a file

The following example specifies a directory, and then uses the content property to add a string to the file created in that directory:

status_file = '/path/to/file/status_file'

file status_file do
  owner 'root'
  group 'root'
  mode '0755'
  content 'My favourite foremost coastal Antarctic shelf, oh Larsen B!'
end

Create a file from a copy

The following example shows how to copy a file from one directory to another, locally on a node:

file '/root/1.txt' do
  content IO.read('/tmp/1.txt')
  action :create
end

where the content attribute uses the Ruby IO.read method to get the contents of the /tmp/1.txt file.