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YAML:
ain’t:
markup:
- language
@KeithResar
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An:
unfortunate:
series:
of:
- indents
@KeithResar
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@KeithResar
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@KeithResar
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@KeithResar
ANSIBLE YAML
---
- hosts: localhost
tasks:
- debug:
msg: "Hello World"
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@KeithResar
KUBERNETES YAML
---
apiVersion: v1
kind: Pod
metadata:
...
spec:
...
status:
...
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@KeithResar
CALENZEN YAML
---
name: Zoom US Level 1 (2018-09-05)
level: 1
priority: 102
driver: RegexV1
key_type: ...
detect_regex: …
output: ...
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@KeithResar
RFC 822
From: [email protected]
To: [email protected],
∙ ∙ ∙ "[email protected]"
Unstructured Text
Key/Value pairs
Multi-line folding
CRLF followed by LWSP character
Delimiting and Quoting
Optional, not part of string, c-style
escape sequences
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@KeithResar
OTHER PRIOR ART
● Indentation-based scoping from Python
● End of line normalization from HTML
● Collections & scalar data types from Perl, Python, Ruby
● Incremental interfaces and streaming one-pass
interfaces supports large documents
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@KeithResar
COMPARING YAML WITH JSON
● Simplicity & universality
● Lowest common
denominator
● Trivial to generate and
parse
JSON
● Human readability
● Arbitrary native data
structures
● Complex processing
across environments
YAML
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@KeithResar
YAML ⊇ JSON
JSON's RFC4627 requires that mappings keys merely
“SHOULD” be unique, while YAML insists they “MUST” be.
Technically, YAML therefore complies with the JSON spec,
choosing to treat duplicates as an error.
In practice, since JSON is silent on the semantics of such
duplicates, the only portable JSON files are those with
unique keys, which are therefore valid YAML files.
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@KeithResar
QUOTING
---
plain: look ma no quotes, but the most limited
single_quotes:
- 'keith''s single quotes'
- 'bare \ is ok'
double_quotes:
- "only flow that can express arbitrary strings"
- "\\ escape sequences, but must quote \" and \\"
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@KeithResar
BLOCKS
---
# literal style
- a: |
multi-line
∙ ∙ ∙ text block
# folded style
- b: >
multi-line
∙ ∙ ∙ text block
Becomes:
multi-line
Text block
Becomes:
Multi-line text block
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@KeithResar
BLOCK CHOMPING
---
# clip (default) - includes final line break
- a: |
text
# strip - excludes final line break & trailing empty lines
- a: |-
text
# keep - includes all trailing line breaks
- a: |+
text
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@KeithResar
DIRECTIVES
---
---
...
Start of Stream
Separate directives from content
End of Document
Used for streaming comm channels
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@KeithResar
TAGS IN _FAILSAFE_ SCHEMA
---
- just a string
- true
-
a: 1
b: 2
-
- a
- b
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@KeithResar
TAGS IN _FAILSAFE_ SCHEMA
---
- !!str just a string
- !!str true
- !!map
a: 1
b: 2
- !!seq
- a
- b
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@KeithResar
TAGS IN _JSON_ SCHEMA
---
- just a string
- true
-
a: 1
b: 2
-
- a
- b
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@KeithResar
TAGS IN _CUSTOM_ SCHEMA
%TAG !foo! tag:example.com,2002:
---
invoice1: !foo!invoice
...
invoice2: !
...
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@KeithResar
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@KeithResar
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@KeithResar
LINTING
● YMMV re: quality - check web and python
● yamllint
● ansible-lint
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@KeithResar
EDITORS
● vim
● Atom
● Eclipse
● Visual Studio Code
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@KeithResar
GO FARTHER WITH THESE _RESOURCES_
YAML Ain’t Markup Language (YAML™) Version 1.2 Spec
https://yaml.org/spec/1.2/spec.html
Ansible Lint Documentation
https://docs.ansible.com/ansible-lint/
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THANKS
@KeithResar