internet/community.general
3
0
Fork 0
mirror of https://github.com/ansible-collections/community.general.git synced 2026-05-06 13:22:48 +00:00
Code Issues Packages Projects Releases Wiki Activity

updated plugin docs (#30490)

Browse Source 
* updated  docs

- for devs:
  - added inventory/vars section
  - made some updates to general section and other plugin types
- for users:
 - added 'user' plugin section to start describing the plugins
 - docs on types, what they are and how to use

- removed ref to deleted AUTHORS file
- corrected several typos/headers
- added descriptions to config.rst template
- ignore generated files for cli/plugins and config
- remove new generated files on `make clean`
- moved details from devguid and intro doc to plugin specific pages
- pretied up lookup notes
- changed precedence ref to not conflict config
- removed duplicate config data, as config is autogenerated and up to date
- put new plugins under playbooks
- added `pass` cause rst/python dislikes fractions
- removed dupe in .gitignore, alpha sorted to avoid moar dupes
- added try cause rst/python freaks out

* generate plugins into their own dir

only do plugins that support docs
use toctree from main plugins page
This commit is contained in:
Brian Coca
2017-09-22 23:19:50 -04:00
committed by GitHub
parent 7a312b6cf7
commit b233f3f296
23 changed files with 873 additions and 1360 deletions
Download Patch File Download Diff File Expand all files Collapse all files

279
docs/docsite/rst/dev_guide/developing_plugins.rst
View File

@@ -4,99 +4,107 @@ Developing Plugins
.. contents:: Topics
Plugins are pieces of code that augment Ansible's core functionality. Ansible ships with a number of handy plugins, and you can easily write your own.
The following types of plugins are available:
- *Action* plugins are front ends to modules and can execute actions on the controller before calling the modules themselves.
- *Cache* plugins are used to keep a cache of 'facts' to avoid costly fact-gathering operations.
- *Callback* plugins enable you to hook into Ansible events for display or logging purposes.
- *Connection* plugins define how to communicate with inventory hosts.
- *Filters* plugins allow you to manipulate data inside Ansible plays and/or templates. This is a Jinja2 feature; Ansible ships extra filter plugins.
- *Lookup* plugins are used to pull data from an external source. These are implemented using a custom Jinja2 function.
- *Strategy* plugins control the flow of a play and execution logic.
- *Shell* plugins deal with low-level commands and formatting for the different shells Ansible can encounter on remote hosts.
- *Test* plugins allow you to validate data inside Ansible plays and/or templates. This is a Jinja2 feature; Ansible ships extra test plugins.
- *Vars* plugins inject additional variable data into Ansible runs that did not come from an inventory, playbook, or the command line.
This section describes the various types of plugins and how to implement them.
.. _plugin_guidelines:
General Guidelines
------------------
Some things that should apply to any type of plugin you develop.
Raising Errors
``````````````
In general, errors encountered during execution should be returned by raising AnsibleError() or similar class with a message describing the error.
When wrapping other exceptions into error messages you should always use the `to_text` Ansible function to ensure proper string compatiblity across
Python versions:
.. code-block:: python
from ansible.module_utils._text import to_native
try:
cause_an_exeption()
except Exception as e:
AnsibleError('Something happend, this was original exception: %s' % to_native(e))
Check the different AnsibleError objects and see which one applies the best to your situation.
String encoding
```````````````
Any strings returned by your plugin that could ever contain non-ASCII characters must be converted into Python's unicode type
because the strings will be run through jinja2. To do this, you can use:
.. code-block:: python
from ansible.module_utils._text import to_text
result_string = to_text(result_string)
Plugin configuration
````````````````````
Starting in 2.4 and going forward, we are unifying how each plugin type is configured and how they get those settings, plugins will be able to 'declare'
their needs and have Ansible provide them with the 'resolved' configuration. As of 2.4 both Callback and Connection type plugins can use this system,
most plugins will be able to use `self._options[<optionname>]` to access the settings, except callbacks that due to prexisting collsion
use `self._plugin_optoins[<optionname>]`.
Plugins that supprot docs (see `ansible-doc` for the list) are now required to provide documentation to be considered for merge into the Ansible repo.
Also be aware that if you inherit from a plugin you must ALSO document the optoins it takes, either via a documentation fragment or as a copy.
.. _developing_callbacks:
Callback Plugins
----------------
Callback plugins enable adding new behaviors to Ansible when responding to events. By default, callback plugins control most of the output you see when running the command line programs.
See :doc: plugins/callback as to what they are and how to use them. This section explains how to use them.
.. _callback_examples:
Example Callback Plugins
++++++++++++++++++++++++
Ansible comes with a number of callback plugins that you can look at for examples. These can be found in `lib/ansible/plugins/callback <https://github.com/ansible/ansible/tree/devel/lib/ansible/plugins/callback>`_.
The `log_plays
<https://github.com/ansible/ansible/blob/devel/lib/ansible/plugins/callback/log_plays.py>`_
callback is an example of how to intercept playbook events to a log
file, and the `mail
<https://github.com/ansible/ansible/blob/devel/lib/ansible/plugins/callback/mail.py>`_
callback sends email when playbooks complete.
The `osx_say
<https://github.com/ansible/ansible/blob/devel/lib/ansible/plugins/callback/osx_say.py>`_
callback provided is particularly entertaining -- it will respond with
computer synthesized speech on OS X in relation to playbook events,
and is guaranteed to entertain and/or annoy coworkers.
.. _configuring_callbacks:
Configuring Callback Plugins
++++++++++++++++++++++++++++
You can activate a custom callback by either dropping it into a callback_plugins directory adjacent to your play or inside a role or by putting it in one of the callback directory sources configured in `ansible.cfg`.
Plugins are loaded in alphanumeric order; for example, a plugin implemented in a file named `1_first.py` would run before a plugin file named `2_second.py`.
Most callbacks shipped with Ansible are disabled by default and need to be whitelisted in your `ansible.cfg` file in order to function. For example::
#callback_whitelist = timer, mail, mycallbackplugin
Managing stdout
```````````````
You can only have one plugin be the main manager of your console output. If you want to replace the default, you should define CALLBACK_TYPE = stdout in the subclass and then configure the stdout plugin in `ansible.cfg`. For example::
#stdout_callback = mycallbackplugin
.. _callback_development:
Developing Callback Plugins
+++++++++++++++++++++++++++
Callback plugins are created by creating a new class with the Base(Callbacks) class as the parent:
.. code-block:: python
from ansible.plugins.callback import CallbackBase
from ansible import constants as C
class CallbackModule(CallbackBase):
pass
From there, override the specific methods from the CallbackBase that you want to provide a callback for. For plugins intended for use with Ansible version 2.0 and later, you should only override methods that start with `v2`. For a complete list of methods that you can override, please see ``__init__.py`` in the `lib/ansible/plugins/callback <https://github.com/ansible/ansible/tree/devel/lib/ansible/plugins/callback>`_ directory.
From there, override the specific methods from the CallbackBase that you want to provide a callback for.
For plugins intended for use with Ansible version 2.0 and later, you should only override methods that start with `v2`.
For a complete list of methods that you can override, please see ``__init__.py`` in the
`lib/ansible/plugins/callback <https://github.com/ansible/ansible/tree/devel/lib/ansible/plugins/callback>`_ directory.
The following example shows how Ansible's timer plugin is implemented:
The following example shows a modified example Ansible's timer plugin is implemented,
but with an extra option so you can see how configuration works in Ansible >= 2.4:
.. code-block:: python
# Make coding more python3-ish
# Make coding more python3-ish, this is required for contributions to Ansible
from __future__ import (absolute_import, division, print_function)
__metaclass__ = type
# not only visible to ansible-doc, it also 'declares' the options the plugin requires and how to configure them.
DOCUMENTATION = '''
callback: timer
callback_type: aggregate
requirements:
- whitelist in configuration
short_description: Adds time to play stats
version_added: "2.0"
description:
- This callback just adds total play duration to the play stats.
options:
format_string:
description: format of the string shown to user at play end
ini:
- section: callback_timer
key: format_string
env:
- name: ANSIBLE_CALLBACK_TIMER_FORMAT
default: "Playbook run took %s days, %s hours, %s minutes, %s seconds"
'''
from datetime import datetime
from ansible.plugins.callback import CallbackBase
@@ -109,28 +117,35 @@ The following example shows how Ansible's timer plugin is implemented:
CALLBACK_VERSION = 2.0
CALLBACK_TYPE = 'aggregate'
CALLBACK_NAME = 'timer'
# only needed if you ship it and dont want to enable by default
CALLBACK_NEEDS_WHITELIST = True
def __init__(self):
# make sure the expected objects are present, calling the base's __init__
super(CallbackModule, self).__init__()
# start the timer when the plugin is loaded, the first play should start a few miliseconds after.
self.start_time = datetime.now()
def days_hours_minutes_seconds(self, runtime):
def _days_hours_minutes_seconds(self, runtime):
''' internal helper method for this callback '''
minutes = (runtime.seconds // 60) % 60
r_seconds = runtime.seconds - (minutes * 60)
return runtime.days, runtime.seconds // 3600, minutes, r_seconds
def playbook_on_stats(self, stats):
self.v2_playbook_on_stats(stats)
# this is only event we care about for display, when the play shows it's summary stats, the rest are ignored by the base class
def v2_playbook_on_stats(self, stats):
end_time = datetime.now()
runtime = end_time - self.start_time
self._display.display("Playbook run took %s days, %s hours, %s minutes, %s seconds" % (self.days_hours_minutes_seconds(runtime)))
# Shows the usage of a config option declared in the DOCUMENTATION variable, Ansible will have set it when it loads the plugin.
# Also note the use of the display object to print to screen, available to all callbacks, you should prefer this over printing yoruself
self._display.display(self._plugin_options['format_string'] % (self._days_hours_minutes_seconds(runtime)))
Note that the CALLBACK_VERSION and CALLBACK_NAME definitions are required for properly functioning plugins for Ansible >=2.0.
CALLBACK_TYPE is mostly needed to distinguish 'stout' plugins from the rest, as you can only load one of that type.
.. _developing_connection_plugins:
@@ -142,7 +157,45 @@ are covered in the :doc:`../intro_getting_started` section. Should you want to
directory. The value of 'smart' for a connection allows selection of paramiko or openssh based on system capabilities, and chooses
'ssh' if OpenSSH supports ControlPersist, in Ansible 1.2.1 and later. Previous versions did not support 'smart'.
More documentation on writing connection plugins is pending, though you can jump into `lib/ansible/plugins/connection <https://github.com/ansible/ansible/tree/devel/lib/ansible/plugins/connection>`_ and figure things out pretty easily.
More documentation on writing connection plugins is pending, though you can jump into
`lib/ansible/plugins/connection <https://github.com/ansible/ansible/tree/devel/lib/ansible/plugins/connection>`_ and figure things out pretty easily.
.. _developing_inventory_plugins:
Inventory Plugins
-----------------
Added in Ansible 2.4 they are in charge of parsing inventory sources and forming the 'in memory' representation of the Inventory.
They are invoked via the InventoryManager and are given access to any existing inventory data added previouslly,
they are given an 'inventory source' as supplied to Ansible (via config/optoins/defaults/etc), which they can ignore
(return false from the `verify_file` method), or attempt to parse (via `parse` method) and return an `AnsibleParserError` on failure.
.. code-block:: python
def parse(self, inventory, loader, path, cache=True):
pass # your code goes here
The parameters are:
* inventory: inventory object with existing data and the methods to add hosts/groups/variables to inventory
* loader: Ansible's DataLoader, it can read files, auto load JSON/YAML and decrypt vaulted data, it also caches read filesh.
* path: string with inventory source (normally a path, but not required)
* cache: hint to the plugin if it should use or avoid caches (Cache plugin and/or loader)
Inventory sources are strings, most of the time they correspond to a file path, but can also be a comma separated list,
a uri or anything your plugin can use as input.
The 'inventory source' provided can be either a string (`host_list` plugin), a data file (like consumed by the `yaml` and `ini` plugins),
a configuration file (see `virtualbox` and `constructed`) or even a script or executable (the `script` uses those) which is how 'inventory scripts' work.
Inventory plugins can also use the configured Cache plugin to store and retrieve data to avoid costly external calls,
of course this only works if using a 'persistent' cache (i.e not the memory one).
Be aware that inventory plugins normally only execute at the start of the run, before playbooks/plays and roles are found,
but they can be 're-executed' via the `meta: refresh_inventory` task, which will clear out the existing inventory and rebuild it.
More documentation on writing inventory plugins is pending, though you can jump into
`lib/ansible/plugins/inventory <https://github.com/ansible/ansible/tree/devel/lib/ansible/plugins/inventory>`_ and figure things out pretty easily.
.. _developing_lookup_plugins:
@@ -155,6 +208,25 @@ Here's a simple lookup plugin implementation - this lookup returns the contents
.. code-block:: python
# python 3ish headers, required if submitting to Ansible
from __future__ import (absolute_import, division, print_function)
__metaclass__ = type
DOCUMENTATION = """
lookup: file
author: Daniel Hokka Zakrisson <daniel@hozac.com>
version_added: "0.9"
short_description: read file contents
description:
- This lookup returns the contents from a file on the Ansible controller's file system.
options:
_terms:
description: path(s) of files to read
required: True
notes:
- if read in variable context, the file can be interpreted as YAML if the content is valid to the parser.
- this lookup does not understand 'globing', use the fileglob lookup instead.
"""
from ansible.errors import AnsibleError, AnsibleParserError
from ansible.plugins.lookup import LookupBase
@@ -169,19 +241,28 @@ Here's a simple lookup plugin implementation - this lookup returns the contents
def run(self, terms, variables=None, **kwargs):
ret = []
# lookups in general are expected to both take a list as input and output a list
# this is done so they work with the looping construct `with_`.
ret = []
for term in terms:
display.debug("File lookup term: %s" % term)
# Find the file in the expected search path
# Find the file in the expected search path, using a class method
# that implements the 'expected' search path for Ansible plugins.
lookupfile = self.find_file_in_search_path(variables, 'files', term)
# Don't use print or your own logging, the display class
# takes care of it in a unified way.
display.vvvv(u"File lookup using %s as file" % lookupfile)
try:
if lookupfile:
contents, show_data = self._loader._get_file_contents(lookupfile)
ret.append(contents.rstrip())
else:
# Always use ansible error classes to throw 'final' exceptions,
# so the Ansible engine will know how to deal with them.
# The Parser error indicates invalid options passed
raise AnsibleParserError()
except AnsibleParserError:
raise AnsibleError("could not locate file in lookup: %s" % term)
@@ -199,13 +280,6 @@ An example of how this lookup is called::
- debug: msg="the value of foo.txt is {{ contents }} as seen today {{ lookup('pipe', 'date +"%Y-%m-%d"') }}"
Errors encountered during execution should be returned by raising AnsibleError() with a message describing the error. Any strings returned by your lookup plugin implementation that could ever contain non-ASCII characters must be converted into Python's unicode type because the strings will be run through jinja2. To do this, you can use:
.. code-block:: python
from ansible.module_utils._text import to_text
result_string = to_text(result_string)
For more example lookup plugins, check out the source code for the lookup plugins that are included with Ansible here: `lib/ansible/plugins/lookup <https://github.com/ansible/ansible/tree/devel/lib/ansible/plugins/lookup>`_.
For usage examples of lookup plugins, see `Using Lookups <http://docs.ansible.com/ansible/playbooks_lookups.html>`_.
@@ -215,14 +289,42 @@ For usage examples of lookup plugins, see `Using Lookups <http://docs.ansible.co
Vars Plugins
------------
Playbook constructs like 'host_vars' and 'group_vars' work via 'vars' plugins. They inject additional variable
data into ansible runs that did not come from an inventory, playbook, or command line. Note that variables
can also be returned from inventory, so in most cases, you won't need to write or understand vars_plugins.
Playbook constructs like 'host_vars' and 'group_vars' work via 'vars' plugins.
They inject additional variable data into ansible runs that did not come from an inventory source, playbook, or command line.
More documentation on writing vars plugins is pending, though you can jump into `lib/ansible/plugins <https://github.com/ansible/ansible/tree/devel/lib/ansible/plugins/>`_ and figure
things out pretty easily.
Vars plugins got rewritten in 2.4 and had been semi-functional since 2.0.
Older pugins used a `run` method as their main body/work:
.. code-block:: python
def run(self, name, vault_password=None):
pass # your code goes here
But Ansible 2.0 did not pass passwords to them so vaults were unavilable.
Most of the work now happens in the `get_vars` method which is called from the VariableManager when needed.
.. code-block:: python
def get_vars(self, loader, path, entities):
pass # your code goes here
The parameters are:
* loader: Ansible's DataLoader, it can read files, auto load JSON/YAML and decrypt vaulted data, it also caches read filesh.
* path: this is 'directory data' for every inventory source and the current play's playbook directory, so they can search for data
in reference to them, `get_vars` will be called at least once per available path.
* entities: these are host or group names that are pertinent to the variables needed, the plugin will get called once for hosts and again for groups.
This method just needs to return a dictionary structure with the pertinent variables.
Since Ansible 2.4, vars plugins execute as needed when preparing to execute a task, this avoids the costly 'always execute' that used
to happend during inventory construction.
More documentation on writing vars plugins is pending, though you can jump into
`lib/ansible/plugins/vars <https://github.com/ansible/ansible/tree/devel/lib/ansible/plugins/vars>`_ and figure things out pretty easily.
If you find yourself wanting to write a vars_plugin, it's more likely you should write an inventory script instead.
.. _developing_filter_plugins:
@@ -255,11 +357,14 @@ Plugins are automatically loaded when you have one of the following subfolders a
* lookup_plugins
* callback_plugins
* connection_plugins
* inventory_plugins
* filter_plugins
* strategy_plugins
* cache_plugins
* test_plugins
* shell_plugins
* vars_plugins
When shipped as part of a role, the plugin will be available as soon as the role is called in the play.