601 lines
16 KiB
ReStructuredText
601 lines
16 KiB
ReStructuredText
Jinja2 filters
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==============
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.. contents:: Topics
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Filters in Jinja2 are a way of transforming template expressions from one kind of data into another. Jinja2
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ships with many of these. See `builtin filters`_ in the official Jinja2 template documentation.
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In addition to those, Ansible supplies many more.
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.. _filters_for_formatting_data:
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Filters For Formatting Data
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---------------------------
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The following filters will take a data structure in a template and render it in a slightly different format. These
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are occasionally useful for debugging::
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{{ some_variable | to_json }}
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{{ some_variable | to_yaml }}
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For human readable output, you can use::
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{{ some_variable | to_nice_json }}
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{{ some_variable | to_nice_yaml }}
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Alternatively, you may be reading in some already formatted data::
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{{ some_variable | from_json }}
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{{ some_variable | from_yaml }}
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for example::
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tasks:
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- shell: cat /some/path/to/file.json
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register: result
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- set_fact: myvar="{{ result.stdout | from_json }}"
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.. _filters_used_with_conditionals:
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Filters Often Used With Conditionals
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------------------------------------
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The following tasks are illustrative of how filters can be used with conditionals::
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tasks:
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- shell: /usr/bin/foo
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register: result
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ignore_errors: True
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- debug: msg="it failed"
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when: result|failed
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# in most cases you'll want a handler, but if you want to do something right now, this is nice
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- debug: msg="it changed"
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when: result|changed
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- debug: msg="it succeeded"
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when: result|success
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- debug: msg="it was skipped"
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when: result|skipped
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.. _forcing_variables_to_be_defined:
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Forcing Variables To Be Defined
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-------------------------------
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The default behavior from ansible and ansible.cfg is to fail if variables are undefined, but you can turn this off.
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This allows an explicit check with this feature off::
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{{ variable | mandatory }}
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The variable value will be used as is, but the template evaluation will raise an error if it is undefined.
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.. _defaulting_undefined_variables:
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Defaulting Undefined Variables
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------------------------------
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Jinja2 provides a useful 'default' filter, that is often a better approach to failing if a variable is not defined::
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{{ some_variable | default(5) }}
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In the above example, if the variable 'some_variable' is not defined, the value used will be 5, rather than an error
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being raised.
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.. _omitting_undefined_variables:
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Omitting Undefined Variables and Parameters
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-------------------------------------------
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As of Ansible 1.8, it is possible to use the default filter to omit variables and module parameters using the special
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`omit` variable::
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- name: touch files with an optional mode
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file: dest={{item.path}} state=touch mode={{item.mode|default(omit)}}
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with_items:
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- path: /tmp/foo
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- path: /tmp/bar
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- path: /tmp/baz
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mode: "0444"
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For the first two files in the list, the default mode will be determined by the umask of the system as the `mode=`
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parameter will not be sent to the file module while the final file will receive the `mode=0444` option.
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.. note:: If you are "chaining" additional filters after the `default(omit)` filter, you should instead do something like this:
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`"{{ foo | default(None) | some_filter or omit }}"`. In this example, the default `None` (python null) value will cause the
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later filters to fail, which will trigger the `or omit` portion of the logic. Using omit in this manner is very specific to
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the later filters you're chaining though, so be prepared for some trial and error if you do this.
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.. _list_filters:
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List Filters
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------------
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These filters all operate on list variables.
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.. versionadded:: 1.8
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To get the minimum value from list of numbers::
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{{ list1 | min }}
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To get the maximum value from a list of numbers::
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{{ [3, 4, 2] | max }}
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.. _set_theory_filters:
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Set Theory Filters
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------------------
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All these functions return a unique set from sets or lists.
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.. versionadded:: 1.4
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To get a unique set from a list::
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{{ list1 | unique }}
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To get a union of two lists::
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{{ list1 | union(list2) }}
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To get the intersection of 2 lists (unique list of all items in both)::
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{{ list1 | intersect(list2) }}
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To get the difference of 2 lists (items in 1 that don't exist in 2)::
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{{ list1 | difference(list2) }}
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To get the symmetric difference of 2 lists (items exclusive to each list)::
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{{ list1 | symmetric_difference(list2) }}
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.. _version_comparison_filters:
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Version Comparison Filters
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--------------------------
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.. versionadded:: 1.6
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To compare a version number, such as checking if the ``ansible_distribution_version``
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version is greater than or equal to '12.04', you can use the ``version_compare`` filter.
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The ``version_compare`` filter can also be used to evaluate the ``ansible_distribution_version``::
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{{ ansible_distribution_version | version_compare('12.04', '>=') }}
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If ``ansible_distribution_version`` is greater than or equal to 12, this filter will return True, otherwise it will return False.
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The ``version_compare`` filter accepts the following operators::
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<, lt, <=, le, >, gt, >=, ge, ==, =, eq, !=, <>, ne
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This filter also accepts a 3rd parameter, ``strict`` which defines if strict version parsing should
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be used. The default is ``False``, and if set as ``True`` will use more strict version parsing::
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{{ sample_version_var | version_compare('1.0', operator='lt', strict=True) }}
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.. _random_filter:
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Random Number Filter
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--------------------
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.. versionadded:: 1.6
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This filter can be used similar to the default jinja2 random filter (returning a random item from a sequence of
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items), but can also generate a random number based on a range.
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To get a random item from a list::
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{{ ['a','b','c']|random }} => 'c'
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To get a random number from 0 to supplied end::
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{{ 59 |random}} * * * * root /script/from/cron
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Get a random number from 0 to 100 but in steps of 10::
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{{ 100 |random(step=10) }} => 70
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Get a random number from 1 to 100 but in steps of 10::
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{{ 100 |random(1, 10) }} => 31
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{{ 100 |random(start=1, step=10) }} => 51
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Shuffle Filter
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--------------
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.. versionadded:: 1.8
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This filter will randomize an existing list, giving a different order every invocation.
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To get a random list from an existing list::
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{{ ['a','b','c']|shuffle }} => ['c','a','b']
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{{ ['a','b','c']|shuffle }} => ['b','c','a']
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note that when used with a non 'listable' item it is a noop, otherwise it always returns a list
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.. _math_stuff:
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Math
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--------------------
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.. versionadded:: 1.9
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To see if something is actually a number::
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{{ myvar | isnan }}
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Get the logarithm (default is e)::
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{{ myvar | log }}
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Get the base 10 logarithm::
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{{ myvar | log(10) }}
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Give me the power of 2! (or 5)::
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{{ myvar | pow(2) }}
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{{ myvar | pow(5) }}
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Square root, or the 5th::
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{{ myvar | root }}
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{{ myvar | root(5) }}
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Note that jinja2 already provides some like abs() and round().
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.. _ipaddr_filter:
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IP address filter
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-----------------
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.. versionadded:: 1.9
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To test if a string is a valid IP address::
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{{ myvar | ipaddr }}
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You can also require a specific IP protocol version::
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{{ myvar | ipv4 }}
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{{ myvar | ipv6 }}
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IP address filter can also be used to extract specific information from an IP
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address. For example, to get the IP address itself from a CIDR, you can use::
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{{ '192.0.2.1/24' | ipaddr('address') }}
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More information about ``ipaddr`` filter and complete usage guide can be found
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in :doc:`playbooks_filters_ipaddr`.
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.. _hash_filters:
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Hashing filters
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--------------------
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.. versionadded:: 1.9
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To get the sha1 hash of a string::
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{{ 'test1'|hash('sha1') }}
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To get the md5 hash of a string::
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{{ 'test1'|hash('md5') }}
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Get a string checksum::
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{{ 'test2'|checksum }}
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Other hashes (platform dependent)::
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{{ 'test2'|hash('blowfish') }}
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To get a sha512 password hash (random salt)::
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{{ 'passwordsaresecret'|password_hash('sha512') }}
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To get a sha256 password hash with a specific salt::
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{{ 'secretpassword'|password_hash('sha256', 'mysecretsalt') }}
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Hash types available depend on the master system running ansible,
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'hash' depends on hashlib password_hash depends on crypt.
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.. _combine_filter:
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Combining hashes/dictionaries
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-----------------------------
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.. versionadded:: 2.0
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The `combine` filter allows hashes to be merged. For example, the
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following would override keys in one hash::
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{{ {'a':1, 'b':2}|combine({'b':3}) }}
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The resulting hash would be::
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{'a':1, 'b':3}
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The filter also accepts an optional `recursive=True` parameter to not
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only override keys in the first hash, but also recurse into nested
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hashes and merge their keys too::
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{{ {'a':{'foo':1, 'bar':2}, 'b':2}|combine({'a':{'bar':3, 'baz':4}}, recursive=True) }}
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This would result in::
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{'a':{'foo':1, 'bar':3, 'baz':4}, 'b':2}
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The filter can also take multiple arguments to merge::
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{{ a|combine(b, c, d) }}
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In this case, keys in `d` would override those in `c`, which would
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override those in `b`, and so on.
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This behaviour does not depend on the value of the `hash_behaviour`
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setting in `ansible.cfg`.
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.. _extract_filter:
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Extracting values from containers
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---------------------------------
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.. versionadded:: 2.1
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The `extract` filter is used to map from a list of indices to a list of
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values from a container (hash or array)::
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{{ [0,2]|map('extract', ['x','y','z'])|list }}
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{{ ['x','y']|map('extract', {'x': 42, 'y': 31})|list }}
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The results of the above expressions would be::
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['x', 'z']
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[42, 31]
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The filter can take another argument::
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{{ groups['x']|map('extract', hostvars, 'ec2_ip_address')|list }}
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This takes the list of hosts in group 'x', looks them up in `hostvars`,
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and then looks up the `ec2_ip_address` of the result. The final result
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is a list of IP addresses for the hosts in group 'x'.
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The third argument to the filter can also be a list, for a recursive
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lookup inside the container::
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{{ ['a']|map('extract', b, ['x','y'])|list }}
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This would return a list containing the value of `b['a']['x']['y']`.
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.. _comment_filter:
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Comment Filter
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--------------
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.. versionadded:: 2.0
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The `comment` filter allows to decorate the text with a chosen comment
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style. For example the following::
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{{ "Plain style (default)" | comment }}
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will produce this output::
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#
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# Plain style (default)
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#
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Similar way can be applied style for C (``//...``), C block
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(``/*...*/``), Erlang (``%...``) and XML (``<!--...-->``)::
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{{ "C style" | comment('c') }}
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{{ "C block style" | comment('cblock') }}
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{{ "Erlang style" | comment('erlang') }}
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{{ "XML style" | comment('xml') }}
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It is also possible to fully customize the comment style::
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{{ "Custom style" | comment('plain', prefix='#######\n#', postfix='#\n#######\n ###\n #') }}
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That will create the following output::
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#######
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#
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# Custom style
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#
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#######
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###
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#
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The filter can also be applied to any Ansible variable. For example to
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make the output of the ``ansible_managed`` variable more readable, we can
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change the definition in the ``ansible.cfg`` file to this::
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[defaults]
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ansible_managed = This file is managed by Ansible.%n
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template: {file}
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date: %Y-%m-%d %H:%M:%S
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user: {uid}
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host: {host}
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and then use the variable with the `comment` filter::
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{{ ansible_managed | comment }}
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which will produce this output::
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#
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# This file is managed by Ansible.
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#
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# template: /home/ansible/env/dev/ansible_managed/roles/role1/templates/test.j2
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# date: 2015-09-10 11:02:58
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# user: ansible
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# host: myhost
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#
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.. _other_useful_filters:
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Other Useful Filters
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--------------------
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To add quotes for shell usage::
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- shell: echo {{ string_value | quote }}
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To use one value on true and another on false (new in version 1.9)::
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{{ (name == "John") | ternary('Mr','Ms') }}
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To concatenate a list into a string::
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{{ list | join(" ") }}
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To get the last name of a file path, like 'foo.txt' out of '/etc/asdf/foo.txt'::
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{{ path | basename }}
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To get the last name of a windows style file path (new in version 2.0)::
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{{ path | win_basename }}
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To separate the windows drive letter from the rest of a file path (new in version 2.0)::
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{{ path | win_splitdrive }}
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To get only the windows drive letter::
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{{ path | win_splitdrive | first }}
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To get the rest of the path without the drive letter::
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{{ path | win_splitdrive | last }}
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To get the directory from a path::
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{{ path | dirname }}
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To get the directory from a windows path (new version 2.0)::
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{{ path | win_dirname }}
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To expand a path containing a tilde (`~`) character (new in version 1.5)::
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{{ path | expanduser }}
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To get the real path of a link (new in version 1.8)::
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{{ path | realpath }}
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To get the relative path of a link, from a start point (new in version 1.7)::
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{{ path | relpath('/etc') }}
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To get the root and extension of a path or filename (new in version 2.0)::
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# with path == 'nginx.conf' the return would be ('nginx', '.conf')
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{{ path | splitext }}
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To work with Base64 encoded strings::
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{{ encoded | b64decode }}
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{{ decoded | b64encode }}
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To create a UUID from a string (new in version 1.9)::
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{{ hostname | to_uuid }}
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To cast values as certain types, such as when you input a string as "True" from a vars_prompt and the system
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doesn't know it is a boolean value::
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- debug: msg=test
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when: some_string_value | bool
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To match strings against a regex, use the "match" or "search" filter::
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vars:
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url: "http://example.com/users/foo/resources/bar"
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tasks:
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- shell: "msg='matched pattern 1'"
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when: url | match("http://example.com/users/.*/resources/.*")
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- debug: "msg='matched pattern 2'"
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when: url | search("/users/.*/resources/.*")
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'match' will require a complete match in the string, while 'search' will require a match inside of the string.
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.. versionadded:: 1.6
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To replace text in a string with regex, use the "regex_replace" filter::
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# convert "ansible" to "able"
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{{ 'ansible' | regex_replace('^a.*i(.*)$', 'a\\1') }}
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# convert "foobar" to "bar"
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{{ 'foobar' | regex_replace('^f.*o(.*)$', '\\1') }}
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# convert "localhost:80" to "localhost, 80" using named groups
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{{ 'localhost:80' | regex_replace('^(?P<host>.+):(?P<port>\\d+)$', '\\g<host>, \\g<port>') }}
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.. note:: Prior to ansible 2.0, if "regex_replace" filter was used with variables inside YAML arguments (as opposed to simpler 'key=value' arguments),
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then you needed to escape backreferences (e.g. ``\\1``) with 4 backslashes (``\\\\``) instead of 2 (``\\``).
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.. versionadded:: 2.0
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To escape special characters within a regex, use the "regex_escape" filter::
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# convert '^f.*o(.*)$' to '\^f\.\*o\(\.\*\)\$'
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{{ '^f.*o(.*)$' | regex_escape() }}
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To make use of one attribute from each item in a list of complex variables, use the "map" filter (see the `Jinja2 map() docs`_ for more)::
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# get a comma-separated list of the mount points (e.g. "/,/mnt/stuff") on a host
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{{ ansible_mounts|map(attribute='mount')|join(',') }}
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A few useful filters are typically added with each new Ansible release. The development documentation shows
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how to extend Ansible filters by writing your own as plugins, though in general, we encourage new ones
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to be added to core so everyone can make use of them.
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.. _Jinja2 map() docs: http://jinja.pocoo.org/docs/dev/templates/#map
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.. _builtin filters: http://jinja.pocoo.org/docs/templates/#builtin-filters
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.. seealso::
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:doc:`playbooks`
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An introduction to playbooks
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:doc:`playbooks_conditionals`
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Conditional statements in playbooks
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:doc:`playbooks_variables`
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All about variables
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:doc:`playbooks_loops`
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Looping in playbooks
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:doc:`playbooks_roles`
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Playbook organization by roles
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:doc:`playbooks_best_practices`
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Best practices in playbooks
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`User Mailing List <http://groups.google.com/group/ansible-devel>`_
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Have a question? Stop by the google group!
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`irc.freenode.net <http://irc.freenode.net>`_
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#ansible IRC chat channel
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