community.general.filesize module – Create a file with a given size, or resize it if it exists

Note

This module is part of the community.general collection (version 5.4.0).

You might already have this collection installed if you are using the ansible package. It is not included in ansible-core. To check whether it is installed, run ansible-galaxy collection list.

To install it, use: ansible-galaxy collection install community.general.

To use it in a playbook, specify: community.general.filesize.

New in version 3.0.0: of community.general

Synopsis

  • This module is a simple wrapper around dd to create, extend or truncate a file, given its size. It can be used to manage swap files (that require contiguous blocks) or alternatively, huge sparse files.

Requirements

The below requirements are needed on the host that executes this module.

  • dd (Data Duplicator) in PATH

Parameters

Parameter

Comments

attributes

aliases: attr

string

added in 2.3 of ansible.builtin

The attributes the resulting filesystem object should have.

To get supported flags look at the man page for chattr on the target system.

This string should contain the attributes in the same order as the one displayed by lsattr.

The = operator is assumed as default, otherwise + or - operators need to be included in the string.

blocksize

raw

Size of blocks, in bytes if not followed by a multiplicative suffix.

The numeric value (before the unit) MUST be an integer (or a float if it equals an integer).

If not set, the size of blocks is guessed from the OS and commonly results in 512 or 4096 bytes, that is used internally by the module or when size has no unit.

force

boolean

Whether or not to overwrite the file if it exists, in other words, to truncate it from 0. When true, the module is not idempotent, that means it always reports changed=true.

force=true and sparse=true are mutually exclusive.

Choices:

  • no ← (default)

  • yes

group

string

Name of the group that should own the filesystem object, as would be fed to chown.

When left unspecified, it uses the current group of the current user unless you are root, in which case it can preserve the previous ownership.

mode

raw

The permissions the resulting filesystem object should have.

For those used to /usr/bin/chmod remember that modes are actually octal numbers. You must either add a leading zero so that Ansible’s YAML parser knows it is an octal number (like 0644 or 01777) or quote it (like '644' or '1777') so Ansible receives a string and can do its own conversion from string into number.

Giving Ansible a number without following one of these rules will end up with a decimal number which will have unexpected results.

As of Ansible 1.8, the mode may be specified as a symbolic mode (for example, u+rwx or u=rw,g=r,o=r).

If mode is not specified and the destination filesystem object does not exist, the default umask on the system will be used when setting the mode for the newly created filesystem object.

If mode is not specified and the destination filesystem object does exist, the mode of the existing filesystem object will be used.

Specifying mode is the best way to ensure filesystem objects are created with the correct permissions. See CVE-2020-1736 for further details.

owner

string

Name of the user that should own the filesystem object, as would be fed to chown.

When left unspecified, it uses the current user unless you are root, in which case it can preserve the previous ownership.

path

path / required

Path of the regular file to create or resize.

selevel

string

The level part of the SELinux filesystem object context.

This is the MLS/MCS attribute, sometimes known as the range.

When set to _default, it will use the level portion of the policy if available.

serole

string

The role part of the SELinux filesystem object context.

When set to _default, it will use the role portion of the policy if available.

setype

string

The type part of the SELinux filesystem object context.

When set to _default, it will use the type portion of the policy if available.

seuser

string

The user part of the SELinux filesystem object context.

By default it uses the system policy, where applicable.

When set to _default, it will use the user portion of the policy if available.

size

raw / required

Requested size of the file.

The value is a number (either int or float) optionally followed by a multiplicative suffix, that can be one of B (bytes), KB or kB (= 1000B), MB or mB (= 1000kB), GB or gB (= 1000MB), and so on for T, P, E, Z and Y; or alternatively one of K, k or KiB (= 1024B); M, m or MiB (= 1024KiB); G, g or GiB (= 1024MiB); and so on.

If the multiplicative suffix is not provided, the value is treated as an integer number of blocks of blocksize bytes each (float values are rounded to the closest integer).

When the size value is equal to the current file size, does nothing.

When the size value is bigger than the current file size, bytes from source (if sparse is not false) are appended to the file without truncating it, in other words, without modifying the existing bytes of the file.

When the size value is smaller than the current file size, it is truncated to the requested value without modifying bytes before this value.

That means that a file of any arbitrary size can be grown to any other arbitrary size, and then resized down to its initial size without modifying its initial content.

source

path

Device or file that provides input data to provision the file.

This parameter is ignored when sparse=true.

Default: “/dev/zero”

sparse

boolean

Whether or not the file to create should be a sparse file.

This option is effective only on newly created files, or when growing a file, only for the bytes to append.

This option is not supported on OSes or filesystems not supporting sparse files.

force=true and sparse=true are mutually exclusive.

Choices:

  • no ← (default)

  • yes

unsafe_writes

boolean

added in 2.2 of ansible.builtin

This option is silently ignored. This module always modifies file size in-place.

Choices:

  • no ← (default)

  • yes

Notes

Note

  • This module supports check_mode and diff.

See Also

See also

dd(1) manpage for Linux

Manual page of the GNU/Linux’s dd implementation (from GNU coreutils).

dd(1) manpage for IBM AIX

Manual page of the IBM AIX’s dd implementation.

dd(1) manpage for Mac OSX

Manual page of the Mac OSX’s dd implementation.

dd(1M) manpage for Solaris

Manual page of the Oracle Solaris’s dd implementation.

dd(1) manpage for FreeBSD

Manual page of the FreeBSD’s dd implementation.

dd(1) manpage for OpenBSD

Manual page of the OpenBSD’s dd implementation.

dd(1) manpage for NetBSD

Manual page of the NetBSD’s dd implementation.

busybox(1) manpage for Linux

Manual page of the GNU/Linux’s busybox, that provides its own dd implementation.

Examples

- name: Create a file of 1G filled with null bytes
  community.general.filesize:
    path: /var/bigfile
    size: 1G

- name: Extend the file to 2G (2*1024^3)
  community.general.filesize:
    path: /var/bigfile
    size: 2G

- name: Reduce the file to 2GB (2*1000^3)
  community.general.filesize:
    path: /var/bigfile
    size: 2GB

- name: Fill a file with random bytes for backing a LUKS device
  community.general.filesize:
    path: ~/diskimage.luks
    size: 512.0 MiB
    source: /dev/urandom

- name: Take a backup of MBR boot code into a file, overwriting it if it exists
  community.general.filesize:
    path: /media/sdb1/mbr.bin
    size: 440B
    source: /dev/sda
    force: true

- name: Create/resize a sparse file of/to 8TB
  community.general.filesize:
    path: /var/local/sparsefile
    size: 8TB
    sparse: true

- name: Create a file with specific size and attributes, to be used as swap space
  community.general.filesize:
    path: /var/swapfile
    size: 2G
    blocksize: 512B
    mode: u=rw,go=
    owner: root
    group: root

Return Values

Common return values are documented here, the following are the fields unique to this module:

Key

Description

cmd

string

Command executed to create or resize the file.

Returned: when changed or failed

Sample: “/usr/bin/dd if=/dev/zero of=/var/swapfile bs=1048576 seek=3072 count=1024”

filesize

dictionary

Dictionary of sizes related to the file.

Returned: always

blocks

integer

Number of blocks in the file.

Returned: success

Sample: 500

blocksize

integer

Size of the blocks in bytes.

Returned: success

Sample: 1024

bytes

integer

Size of the file, in bytes, as the product of blocks and blocksize.

Returned: success

Sample: 512000

iec

string

Size of the file, in human-readable format, following IEC standard.

Returned: success

Sample: “500.0 KiB”

si

string

Size of the file, in human-readable format, following SI standard.

Returned: success

Sample: “512.0 kB”

path

string

Realpath of the file if it is a symlink, otherwise the same than module’s param.

Returned: always

Sample: “/var/swap0”

size_diff

integer

Difference (positive or negative) between old size and new size, in bytes.

Returned: always

Sample: -1234567890

Authors

  • quidame (@quidame)