Tests¶
Topics
Tests in Jinja are a way of evaluating template expressions and returning True or False. Jinja ships with many of these. See builtin tests in the official Jinja template documentation.
The main difference between tests and filters are that Jinja tests are used for comparisons, whereas filters are used for data manipulation, and have different applications in jinja. Tests can also be used in list processing filters, like map()
and select()
to choose items in the list.
Like all templating, tests always execute on the Ansible controller, not on the target of a task, as they test local data.
In addition to those Jinja2 tests, Ansible supplies a few more and users can easily create their own.
Test syntax¶
Test syntax varies from filter syntax (variable | filter
). Historically Ansible has registered tests as both jinja tests and jinja filters, allowing for them to be referenced using filter syntax.
As of Ansible 2.5, using a jinja test as a filter will generate a warning.
The syntax for using a jinja test is as follows:
variable is test_name
Such as:
result is failed
Testing strings¶
To match strings against a substring or a regular expression, use the “match”, “search” or “regex” filters:
vars:
url: "http://example.com/users/foo/resources/bar"
tasks:
- debug:
msg: "matched pattern 1"
when: url is match("http://example.com/users/.*/resources/.*")
- debug:
msg: "matched pattern 2"
when: url is search("/users/.*/resources/.*")
- debug:
msg: "matched pattern 3"
when: url is search("/users/")
- debug:
msg: "matched pattern 4"
when: url is regex("example.com/\w+/foo")
‘match’ requires zero or more characters at the beginning of the string, while ‘search’ only requires matching a subset of the string. By default, ‘regex’ works like search, but regex can be configured to perform other tests as well.
Version Comparison¶
New in version 1.6.
Note
In 2.5 version_compare
was renamed to version
To compare a version number, such as checking if the ansible_facts['distribution_version']
version is greater than or equal to ‘12.04’, you can use the version
test.
The version
test can also be used to evaluate the ansible_facts['distribution_version']
:
{{ ansible_facts['distribution_version'] is version('12.04', '>=') }}
If ansible_facts['distribution_version']
is greater than or equal to 12.04, this test returns True, otherwise False.
The version
test accepts the following operators:
<, lt, <=, le, >, gt, >=, ge, ==, =, eq, !=, <>, ne
This test also accepts a 3rd parameter, strict
which defines if strict version parsing as defined by distutils.version.StrictVersion
should be used. The default is False
(using distutils.version.LooseVersion
), True
enables strict version parsing:
{{ sample_version_var is version('1.0', operator='lt', strict=True) }}
Set theory tests¶
New in version 2.1.
Note
In 2.5 issubset
and issuperset
were renamed to subset
and superset
To see if a list includes or is included by another list, you can use ‘subset’ and ‘superset’:
vars:
a: [1,2,3,4,5]
b: [2,3]
tasks:
- debug:
msg: "A includes B"
when: a is superset(b)
- debug:
msg: "B is included in A"
when: b is subset(a)
Test if a list contains a value¶
New in version 2.8.
Ansible includes a contains
test which operates similarly, but in reverse of the Jinja2 provided in
test.
The contains
test is designed to work with the select
, reject
, selectattr
, and rejectattr
filters:
vars:
lacp_groups:
- master: lacp0
network: 10.65.100.0/24
gateway: 10.65.100.1
dns4:
- 10.65.100.10
- 10.65.100.11
interfaces:
- em1
- em2
- master: lacp1
network: 10.65.120.0/24
gateway: 10.65.120.1
dns4:
- 10.65.100.10
- 10.65.100.11
interfaces:
- em3
- em4
tasks:
- debug:
msg: "{{ (lacp_groups|selectattr('interfaces', 'contains', 'em1')|first).master }}"
New in version 2.4.
You can use any and all to check if any or all elements in a list are true or not:
vars:
mylist:
- 1
- "{{ 3 == 3 }}"
- True
myotherlist:
- False
- True
tasks:
- debug:
msg: "all are true!"
when: mylist is all
- debug:
msg: "at least one is true"
when: myotherlist is any
Testing paths¶
Note
In 2.5 the following tests were renamed to remove the is_
prefix
The following tests can provide information about a path on the controller:
- debug:
msg: "path is a directory"
when: mypath is directory
- debug:
msg: "path is a file"
when: mypath is file
- debug:
msg: "path is a symlink"
when: mypath is link
- debug:
msg: "path already exists"
when: mypath is exists
- debug:
msg: "path is {{ (mypath is abs)|ternary('absolute','relative')}}"
- debug:
msg: "path is the same file as path2"
when: mypath is same_file(path2)
- debug:
msg: "path is a mount"
when: mypath is mount
Task results¶
The following tasks are illustrative of the tests meant to check the status of tasks:
tasks:
- shell: /usr/bin/foo
register: result
ignore_errors: True
- debug:
msg: "it failed"
when: result is failed
# in most cases you'll want a handler, but if you want to do something right now, this is nice
- debug:
msg: "it changed"
when: result is changed
- debug:
msg: "it succeeded in Ansible >= 2.1"
when: result is succeeded
- debug:
msg: "it succeeded"
when: result is success
- debug:
msg: "it was skipped"
when: result is skipped
Note
From 2.1, you can also use success, failure, change, and skip so that the grammar matches, for those who need to be strict about it.
See also
- About Playbooks
An introduction to playbooks
- Conditionals
Conditional statements in playbooks
- Using Variables
All about variables
- Loops
Looping in playbooks
- Roles
Playbook organization by roles
- Best Practices
Best practices in playbooks
- User Mailing List
Have a question? Stop by the google group!
- irc.freenode.net
#ansible IRC chat channel