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97 lines
2.8 KiB
ReStructuredText
Blocks
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======
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In 2.0 we added a block feature to allow for logical grouping of tasks and even
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in play error handling. Most of what you can apply to a single task can be applied
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at the block level, which also makes it much easier to set data or directives common
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to the tasks. This does not mean the directive affects the block itself, but is inherited
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by the tasks enclosed by a block. i.e. a `when` will be applied to the tasks, not the block itself.
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.. code-block:: YAML
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:emphasize-lines: 2
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:caption: Block example
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tasks:
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- block:
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- yum: name={{ item }} state=installed
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with_items:
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- httpd
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- memcached
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- template: src=templates/src.j2 dest=/etc/foo.conf
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- service: name=bar state=started enabled=True
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when: ansible_distribution == 'CentOS'
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become: true
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become_user: root
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In the example above, each of the 3 tasks will be executed after appending the `when` condition from the block
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and evaluating it in the task's context. Also they inherit the privilege escalation directives enabling "become to root"
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for all the enclosed tasks.
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.. _block_error_handling:
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Error Handling
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``````````````
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Blocks also introduce the ability to handle errors in a way similar to exceptions in most programming languages.
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.. code-block:: YAML
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:emphasize-lines: 2,6,10
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:caption: Block error handling example
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tasks:
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- block:
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- debug: msg='i execute normally'
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- command: /bin/false
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- debug: msg='i never execute, cause ERROR!'
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rescue:
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- debug: msg='I caught an error'
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- command: /bin/false
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- debug: msg='I also never execute :-('
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always:
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- debug: msg="this always executes"
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The tasks in the ``block`` would execute normally, if there is any error the ``rescue`` section would get executed
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with whatever you need to do to recover from the previous error. The ``always`` section runs no matter what previous
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error did or did not occur in the ``block`` and ``rescue`` sections.
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Another example is how to run handlers after an error occurred :
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.. code-block:: YAML
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:emphasize-lines: 4,8
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:caption: Block run handlers in error handling
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tasks:
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- block:
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- debug: msg='i execute normally'
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notify: run me even after an error
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- command: /bin/false
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rescue:
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- name: make sure all handlers run
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meta: flush_handlers
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handlers:
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- name: run me even after an error
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debug: msg='this handler runs even on error'
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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_roles`
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Playbook organization by roles
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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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