ansible.builtin.set_fact – Set host variable(s) and fact(s).

Note

This module is part of ansible-core and included in all Ansible installations. In most cases, you can use the short module name set_fact even without specifying the collections: keyword. However, we recommend you use the FQCN for easy linking to the module documentation and to avoid conflicting with other collections that may have the same module name.

New in version 1.2: of ansible.builtin

Synopsis

  • This action allows setting variables associated to the current host.

  • These variables will be available to subsequent plays during an ansible-playbook run via the host they were set on.

  • Set cacheable to yes to save variables across executions using a fact cache. Variables will keep the set_fact precedence for the current run, but will used ‘cached fact’ precedence for subsequent ones.

  • Per the standard Ansible variable precedence rules, other types of variables have a higher priority, so this value may be overridden.

Note

This module has a corresponding action plugin.

Parameters

Parameter Choices/Defaults Comments
cacheable
boolean
added in 2.4 of ansible.builtin
    Choices:
  • no ←
  • yes
This boolean converts the variable into an actual 'fact' which will also be added to the fact cache. It does not enable fact caching across runs, it just means it will work with it if already enabled.
Normally this module creates 'host level variables' and has much higher precedence, this option changes the nature and precedence (by 7 steps) of the variable created. https://docs.ansible.com/ansible/latest/user_guide/playbooks_variables.html#variable-precedence-where-should-i-put-a-variable
This actually creates 2 copies of the variable, a normal 'set_fact' host variable with high precedence and a lower 'ansible_fact' one that is available for persistance via the facts cache plugin. This creates a possibly confusing interaction with meta: clear_facts as it will remove the 'ansible_fact' but not the host variable.
key_value
string / required
The set_fact module takes ``key=value`` pairs or ``key: value``(YAML notation) as variables to set in the playbook scope. The 'key' is the resulting variable name and the value is, of course, the value of said variable.
You can create multiple variables at once, by supplying multiple pairs, but do NOT mix notations.

Attributes

Attribute

Support

Description

action

Support: partial

While the action plugin does do some of the work it relies on the core engine to actually create the variables, that part cannot be overriden

Indicates this has a corresponding action plugin so some parts of the options can be executed on the controller

async

Support: none

Supports being used with the async keyword

become

Support: none

Is usable alongside become keywords

bypass_host_loop

Support: none

Forces a ‘global’ task that does not execute per host, this bypasses per host templating and serial, throttle and other loop considerations

Conditionals will work as if run_once is being used, variables used will be from the first available host

This action will not work normally outside of lockstep strategies

bypass_task_loop

Support: none

These tasks ignore the loop and with_ keywords

check_mode

Support: full

Can run in check_mode and return changed status prediction withought modifying target

connection

Support: none

Uses the target’s configured connection information to execute code on it

core

Support: partial

While parts of this action are implemented in core, other parts are still available as normal plugins and can be partially overridden

This is a ‘core engine’ feature and is not implemented like most task actions, so it is not overridable in any way via the plugin system.

delegation

Support: partial

while variable assignment can be delegated to a different host the execution context is always the current invenotory_hostname

connection variables, if set at all, would reflect the host it would target, even if we are not connecting at all in this case

Can be used in conjunction with delegate_to and related keywords

diff_mode

Support: none

Will return details on what has changed (or possibly needs changing in check_mode), when in diff mode

ignore_conditional

Support: none

The action is not subject to conditional execution so it will ignore the when: keyword

platform

Platforms: all

Target OS/families that can be operated against

tags

Support: full

Allows for the ‘tags’ keyword to control the selection of this action for execution

until

Support: full

Denotes if this action objeys until/retry/poll keywords

Notes

Note

  • Because of the nature of tasks, set_fact will produce ‘static’ values for a variable. Unlike normal ‘lazy’ variables, the value gets evaluated and templated on assignment.

  • Some boolean values (yes, no, true, false) will always be converted to boolean type, unless DEFAULT_JINJA2_NATIVE is enabled. This is done so the var=value booleans, otherwise it would only be able to create strings, but it also prevents using those values to create YAML strings. Using the setting will restrict k=v to strings, but will allow you to specify string or boolean in YAML.

  • To create lists/arrays or dictionary/hashes use YAML notation var: [val1, val2].

  • Since ‘cacheable’ is now a module param, ‘cacheable’ is no longer a valid fact name.

See Also

See also

ansible.builtin.include_vars

The official documentation on the ansible.builtin.include_vars module.

Variable precedence: Where should I put a variable?

More information related to variable precedence and which type of variable wins over others.

Examples

- name: Setting host facts using key=value pairs, this format can only create strings or booleans
  set_fact: one_fact="something" other_fact="{{ local_var }}"

- name: Setting host facts using complex arguments
  set_fact:
    one_fact: something
    other_fact: "{{ local_var * 2 }}"
    another_fact: "{{ some_registered_var.results | map(attribute='ansible_facts.some_fact') | list }}"

- name: Setting facts so that they will be persisted in the fact cache
  set_fact:
    one_fact: something
    other_fact: "{{ local_var * 2 }}"
    cacheable: yes

- name: Creating list and dictionary variables
  set_fact:
    one_dict:
        something: here
        other: there
    one_list:
        - a
        - b
        - c

- name: Creating list and dictionary variables using 'shorthand' YAML
  set_fact:
    two_dict: {'something': here2, 'other': somewhere}
    two_list: [1,2,3]

Authors

  • Dag Wieers (@dagwieers)