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Merge pull request #3628 from jlund/yaml-syntax

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Minor cleanup of YAML Syntax documentation
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Michael DeHaan 2013-07-22 15:20:53 -07:00
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docsite/latest/rst/YAMLSyntax.rst
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@ -4,9 +4,9 @@ YAML Syntax
This page provides a basic overview of correct YAML syntax, which is how Ansible This page provides a basic overview of correct YAML syntax, which is how Ansible
playbooks (our configuration management language) are expressed. playbooks (our configuration management language) are expressed.
We use YAML because it is easier to read and write for humans than other common We use YAML because it is easier for humans to read and write than other common
data formats like XML or JSON. Further, there are libraries available for reading data formats like XML or JSON. Further, there are libraries available in most
and writing YAML in most programming languages. programming languages for working with YAML.
You may also wish to read :doc:`playbooks` at the same time to see how this You may also wish to read :doc:`playbooks` at the same time to see how this
is used in practice. is used in practice.
@ -15,14 +15,14 @@ is used in practice.
YAML Basics YAML Basics
----------- -----------
For `ansible`, nearly every YAML file starts with a list. For Ansible, nearly every YAML file starts with a list.
Each item in the list is a list of key/value pairs, commonly Each item in the list is a list of key/value pairs, commonly
called a "hash" or a "dictionary". So, we need to know how called a "hash" or a "dictionary". So, we need to know how
to write lists and dictionaries in YAML. to write lists and dictionaries in YAML.
There's another small quirk to YAML. All YAML files (regardless of their association with There's another small quirk to YAML. All YAML files (regardless of their association with
`ansible` or not) should start with ``---``. This is just a YAML Ansible or not) should begin with ``---``. This is part of the YAML
format thing that means "this is the start of a document". format and indicates the start of a document.
All members of a list are lines beginning at the same indentation level starting All members of a list are lines beginning at the same indentation level starting
with a ``-`` (dash) character:: with a ``-`` (dash) character::
@ -60,7 +60,7 @@ boolean value (true/false) in several forms::
likes_emacs: TRUE likes_emacs: TRUE
uses_cvs: false uses_cvs: false
Let's combine what we learned so far in an arbitary YAML example. This really Let's combine what we learned so far in an arbitrary YAML example. This really
has nothing to do with Ansible, but will give you a feel for the format:: has nothing to do with Ansible, but will give you a feel for the format::
--- ---
@ -79,13 +79,13 @@ has nothing to do with Ansible, but will give you a feel for the format::
python: Elite python: Elite
dotnet: Lame dotnet: Lame
That's all you really need to know about YAML to get started writing That's all you really need to know about YAML to start writing
`Ansible` playbooks. `Ansible` playbooks.
Gotchas Gotchas
------- -------
While YAML is generally friendly, the following is going to be a YAML syntax error: While YAML is generally friendly, the following is going to result in a YAML syntax error:
foo: somebody said I should put a colon here: so I did foo: somebody said I should put a colon here: so I did
@ -96,7 +96,7 @@ You will want to quote any hash values using colons, like so:
And then the colon will be preserved. And then the colon will be preserved.
Further, Ansible uses "{{ var }}" for variables. If a value after a colon starts Further, Ansible uses "{{ var }}" for variables. If a value after a colon starts
with a "{", YAML will think it a dictionary, so you must quote it, like so:: with a "{", YAML will think it is a dictionary, so you must quote it, like so::
foo: "{{ variable }}" foo: "{{ variable }}"