YAML - An unfortunate series of indents

YAML: ain’t: markup: - language @KeithResar

An: unfortunate: series: of: - indents @KeithResar

@KeithResar

@KeithResar ANSIBLE YAML --- - hosts: localhost tasks: - debug:
msg: "Hello World"

@KeithResar KUBERNETES YAML --- apiVersion: v1 kind: Pod metadata: ...
spec: ... status: ...

@KeithResar CALENZEN YAML --- name: Zoom US Level 1 (2018-09-05)
level: 1 priority: 102 driver: RegexV1 key_type: ... detect_regex: … output: ...

@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

@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

@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

@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.

@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 \\"

@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

@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

@KeithResar DIRECTIVES --- <document content> --- <document content> ... Start
of Stream Separate directives from content End of Document Used for streaming comm channels

@KeithResar TAGS IN _FAILSAFE_ SCHEMA --- - just a string
- true - a: 1 b: 2 - - a - b

@KeithResar TAGS IN _FAILSAFE_ SCHEMA --- - !!str just a
string - !!str true - !!map a: 1 b: 2 - !!seq - a - b

@KeithResar TAGS IN _JSON_ SCHEMA --- - just a string
- true - a: 1 b: 2 - - a - b

@KeithResar TAGS IN _CUSTOM_ SCHEMA %TAG !foo! tag:example.com,2002: --- invoice1:
!foo!invoice ... invoice2: !<tag:example.com,2002:invoice> ...

@KeithResar

@KeithResar LINTING • YMMV re: quality - check web and
python • yamllint • ansible-lint

@KeithResar EDITORS • vim • Atom • Eclipse • Visual
Studio Code

@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/

THANKS @KeithResar

YAML - An unfortunate series of indents

YAML - An unfortunate series of indents

Keith Resar

Transcript

YAML: ain’t: markup: - language @KeithResar

An: unfortunate: series: of: - indents @KeithResar

@KeithResar

@KeithResar

@KeithResar ANSIBLE YAML --- - hosts: localhost tasks: - debug:

@KeithResar KUBERNETES YAML --- apiVersion: v1 kind: Pod metadata: ...

@KeithResar CALENZEN YAML --- name: Zoom US Level 1 (2018-09-05)

@KeithResar RFC 822 From: [email protected] To: [email protected], ∙ ∙ ∙

@KeithResar OTHER PRIOR ART • Indentation-based scoping from Python •

@KeithResar COMPARING YAML WITH JSON • Simplicity & universality •

@KeithResar YAML ⊇ JSON JSON's RFC4627 requires that mappings keys

@KeithResar QUOTING --- plain: look ma no quotes, but the

@KeithResar BLOCKS --- # literal style - a: | multi-line

@KeithResar BLOCK CHOMPING --- # clip (default) - includes final

@KeithResar DIRECTIVES --- <document content> --- <document content> ... Start

@KeithResar TAGS IN _FAILSAFE_ SCHEMA --- - just a string

@KeithResar TAGS IN _FAILSAFE_ SCHEMA --- - !!str just a

@KeithResar TAGS IN _JSON_ SCHEMA --- - just a string

@KeithResar TAGS IN _CUSTOM_ SCHEMA %TAG !foo! tag:example.com,2002: --- invoice1:

@KeithResar

@KeithResar

@KeithResar LINTING • YMMV re: quality - check web and

@KeithResar EDITORS • vim • Atom • Eclipse • Visual

@KeithResar GO FARTHER WITH THESE _RESOURCES_ YAML Ain’t Markup Language

THANKS @KeithResar

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