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@ -4,9 +4,9 @@ YAML Syntax
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This page provides a basic overview of correct YAML syntax, which is how Ansible
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This page provides a basic overview of correct YAML syntax, which is how Ansible
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playbooks (our configuration management language) are expressed.
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playbooks (our configuration management language) are expressed.
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We use YAML because it is easier to read and write for humans than other common
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We use YAML because it is easier for humans to read and write than other common
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data formats like XML or JSON. Further, there are libraries available for reading
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data formats like XML or JSON. Further, there are libraries available in most
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and writing YAML in most programming languages.
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programming languages for working with YAML.
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You may also wish to read :doc:`playbooks` at the same time to see how this
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You may also wish to read :doc:`playbooks` at the same time to see how this
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is used in practice.
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is used in practice.
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@ -15,14 +15,14 @@ is used in practice.
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YAML Basics
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YAML Basics
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-----------
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-----------
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For `ansible`, nearly every YAML file starts with a list.
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For Ansible, nearly every YAML file starts with a list.
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Each item in the list is a list of key/value pairs, commonly
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Each item in the list is a list of key/value pairs, commonly
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called a "hash" or a "dictionary". So, we need to know how
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called a "hash" or a "dictionary". So, we need to know how
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to write lists and dictionaries in YAML.
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to write lists and dictionaries in YAML.
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There's another small quirk to YAML. All YAML files (regardless of their association with
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There's another small quirk to YAML. All YAML files (regardless of their association with
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`ansible` or not) should start with ``---``. This is just a YAML
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Ansible or not) should begin with ``---``. This is part of the YAML
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format thing that means "this is the start of a document".
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format and indicates the start of a document.
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All members of a list are lines beginning at the same indentation level starting
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All members of a list are lines beginning at the same indentation level starting
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with a ``-`` (dash) character::
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with a ``-`` (dash) character::
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@ -60,7 +60,7 @@ boolean value (true/false) in several forms::
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likes_emacs: TRUE
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likes_emacs: TRUE
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uses_cvs: false
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uses_cvs: false
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Let's combine what we learned so far in an arbitary YAML example. This really
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Let's combine what we learned so far in an arbitrary YAML example. This really
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has nothing to do with Ansible, but will give you a feel for the format::
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has nothing to do with Ansible, but will give you a feel for the format::
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---
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---
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@ -76,16 +76,16 @@ has nothing to do with Ansible, but will give you a feel for the format::
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- Mango
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- Mango
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languages:
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languages:
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ruby: Elite
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ruby: Elite
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python: Elite
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python: Elite
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dotnet: Lame
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dotnet: Lame
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That's all you really need to know about YAML to get started writing
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That's all you really need to know about YAML to start writing
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`Ansible` playbooks.
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`Ansible` playbooks.
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Gotchas
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Gotchas
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-------
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-------
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While YAML is generally friendly, the following is going to be a YAML syntax error:
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While YAML is generally friendly, the following is going to result in a YAML syntax error:
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foo: somebody said I should put a colon here: so I did
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foo: somebody said I should put a colon here: so I did
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@ -96,7 +96,7 @@ You will want to quote any hash values using colons, like so:
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And then the colon will be preserved.
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And then the colon will be preserved.
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Further, Ansible uses "{{ var }}" for variables. If a value after a colon starts
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Further, Ansible uses "{{ var }}" for variables. If a value after a colon starts
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with a "{", YAML will think it a dictionary, so you must quote it, like so::
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with a "{", YAML will think it is a dictionary, so you must quote it, like so::
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foo: "{{ variable }}"
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foo: "{{ variable }}"
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