ansible.utils.fact_diff filter – Find the difference between currently set facts

Note

This filter plugin is part of the ansible.utils collection (version 4.1.0).

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 ansible.utils.

To use it in a playbook, specify: ansible.utils.fact_diff.

New in ansible.utils 2.12.0

Synopsis

  • Compare two facts or variables and get a diff.

Keyword parameters

This describes keyword parameters of the filter. These are the values key1=value1, key2=value2 and so on in the following example: input | ansible.utils.fact_diff(key1=value1, key2=value2, ...)

Parameter

Comments

after

any / required

The second fact to be used in the comparison.

before

any / required

The first fact to be used in the comparison.

common

boolean

Show all common lines.

Choices:

  • false ← (default)

  • true

plugin

dictionary

Configure and specify the diff plugin to use

Default: {}

name

string

The diff plugin to use, in fully qualified collection name format.

Default: "ansible.utils.native"

vars

dictionary

Parameters passed to the diff plugin.

Default: {}

skip_lines

list / elements=string

Skip lines matching these regular expressions.

Matches will be removed prior to the diff.

If the provided before and after are a string, they will be split.

Each entry in each list will be cast to a string for the comparison

Examples

- name: Set fact
  ansible.builtin.set_fact:
    before:
      a:
        b:
          c:
            d:
              - 0
              - 1
    after:
      a:
        b:
          c:
            d:
              - 2
              - 3

- name: Show the difference in json format
  ansible.builtin.set_fact:
    result: "{{before | ansible.utils.fact_diff(after)}}"

# TASK [Show the difference in json format] **********************************************************************************************
# ok: [localhost] => {
#     "ansible_facts": {
#         "result": [
#             "--- before",
#             "+++ after",
#             "@@ -3,8 +3,8 @@",
#             "         "b": {",
#             "             "c": {",
#             "                 "d": [",
#             "-                    0,",
#             "-                    1",
#             "+                    2,",
#             "+                    3",
#             "                 ]",
#             "             }",
#             "         }",
#             ""
#         ]
#     },
#     "changed": false
# }

- name: Set fact
  ansible.builtin.set_fact:
    before: "{{ before|ansible.utils.to_paths }}"
    after: "{{ after|ansible.utils.to_paths }}"

- name: Show the difference in path format
  ansible.builtin.set_fact:
    result: "{{before | ansible.utils.fact_diff(after)}}"

# TASK [Show the difference in path format] **********************************************************************************************
# ok: [localhost] => {
#     "ansible_facts": {
#         "result": [
#             "--- before",
#             "+++ after",
#             "@@ -1,4 +1,4 @@",
#             " {",
#             "-    "a.b.c.d[0]": 0,",
#             "-    "a.b.c.d[1]": 1",
#             "+    "a.b.c.d[0]": 2,",
#             "+    "a.b.c.d[1]": 3",
#             " }",
#             ""
#         ]
#     },
#     "changed": false
# }

- name: Set fact
  ansible.builtin.set_fact:
    before: "{{ before|to_nice_yaml }}"
    after: "{{ after|to_nice_yaml }}"

- name: Show the difference in yaml format
  ansible.builtin.set_fact:
    result: "{{before | ansible.utils.fact_diff(after)}}"

# TASK [Show the difference in yaml format] **********************************************************************************************
# ok: [localhost] => {
#     "ansible_facts": {
#         "result": [
#             "--- before",
#             "+++ after",
#             "@@ -1,2 +1,2 @@",
#             "-a.b.c.d[0]: 0",
#             "-a.b.c.d[1]: 1",
#             "+a.b.c.d[0]: 2",
#             "+a.b.c.d[1]: 3",
#             ""
#         ]
#     },
#     "changed": false
# }

Return Value

Key

Description

result

list / elements=string

Returns diff between before and after facts.

Returned: success

Authors

  • Ashwini Mhatre ((@amhatre))

Hint

Configuration entries for each entry type have a low to high priority order. For example, a variable that is lower in the list will override a variable that is higher up.