Rules¶

When linting a document with yamllint, a series of rules (such as line-length, trailing-spaces, etc.) are checked against.

A configuration file can be used to enable or disable these rules, to set their level (error or warning), but also to tweak their options.

This page describes the rules and their options.

List of rules

anchors ¶

Use this rule to report duplicated anchors and aliases referencing undeclared anchors.

Options

Set forbid-undeclared-aliases to true to avoid aliases that reference an anchor that hasn’t been declared (either not declared at all, or declared later in the document).
Set forbid-duplicated-anchors to true to avoid duplications of a same anchor.
Set forbid-unused-anchors to true to avoid anchors being declared but not used anywhere in the YAML document via alias.

Default values (when enabled)

rules:
  anchors:
    forbid-undeclared-aliases: true
    forbid-duplicated-anchors: false
    forbid-unused-anchors: false

Examples

With anchors: {forbid-undeclared-aliases: true}

the following code snippet would PASS:

---
- &anchor
  foo: bar
- *anchor

the following code snippet would FAIL:

---
- &anchor
  foo: bar
- *unknown

the following code snippet would FAIL:

---
- &anchor
  foo: bar
- <<: *unknown
  extra: value

With anchors: {forbid-duplicated-anchors: true}

the following code snippet would PASS:

---
- &anchor1 Foo Bar
- &anchor2 [item 1, item 2]

the following code snippet would FAIL:

---
- &anchor Foo Bar
- &anchor [item 1, item 2]

With anchors: {forbid-unused-anchors: true}

the following code snippet would PASS:

---
- &anchor
  foo: bar
- *anchor

the following code snippet would FAIL:

---
- &anchor
  foo: bar
- items:
  - item1
  - item2

braces ¶

Use this rule to control the use of flow mappings or number of spaces inside braces ({ and }).

Options

forbid is used to forbid the use of flow mappings which are denoted by surrounding braces ({ and }). Use true to forbid the use of flow mappings completely. Use non-empty to forbid the use of all flow mappings except for empty ones.
min-spaces-inside defines the minimal number of spaces required inside braces.
max-spaces-inside defines the maximal number of spaces allowed inside braces.
min-spaces-inside-empty defines the minimal number of spaces required inside empty braces.
max-spaces-inside-empty defines the maximal number of spaces allowed inside empty braces.

Default values (when enabled)

rules:
  braces:
    forbid: false
    min-spaces-inside: 0
    max-spaces-inside: 0
    min-spaces-inside-empty: -1
    max-spaces-inside-empty: -1

Examples

With braces: {forbid: true}

the following code snippet would PASS:
```
object:
  key1: 4
  key2: 8
```
the following code snippet would FAIL:
```
object: { key1: 4, key2: 8 }
```
With braces: {forbid: non-empty}

the following code snippet would PASS:
```
object: {}
```
the following code snippet would FAIL:
```
object: { key1: 4, key2: 8 }
```
With braces: {min-spaces-inside: 0, max-spaces-inside: 0}

the following code snippet would PASS:
```
object: {key1: 4, key2: 8}
```
the following code snippet would FAIL:
```
object: { key1: 4, key2: 8 }
```
With braces: {min-spaces-inside: 1, max-spaces-inside: 3}

the following code snippet would PASS:
```
object: { key1: 4, key2: 8 }
```
the following code snippet would PASS:
```
object: { key1: 4, key2: 8   }
```
the following code snippet would FAIL:
```
object: {    key1: 4, key2: 8   }
```
the following code snippet would FAIL:
```
object: {key1: 4, key2: 8 }
```
With braces: {min-spaces-inside-empty: 0, max-spaces-inside-empty: 0}

the following code snippet would PASS:
```
object: {}
```
the following code snippet would FAIL:
```
object: { }
```
With braces: {min-spaces-inside-empty: 1, max-spaces-inside-empty: -1}

the following code snippet would PASS:
```
object: {         }
```
the following code snippet would FAIL:
```
object: {}
```

brackets ¶

Use this rule to control the use of flow sequences or the number of spaces inside brackets ([ and ]).

Options

forbid is used to forbid the use of flow sequences which are denoted by surrounding brackets ([ and ]). Use true to forbid the use of flow sequences completely. Use non-empty to forbid the use of all flow sequences except for empty ones.
min-spaces-inside defines the minimal number of spaces required inside brackets.
max-spaces-inside defines the maximal number of spaces allowed inside brackets.
min-spaces-inside-empty defines the minimal number of spaces required inside empty brackets.
max-spaces-inside-empty defines the maximal number of spaces allowed inside empty brackets.

Default values (when enabled)

rules:
  brackets:
    forbid: false
    min-spaces-inside: 0
    max-spaces-inside: 0
    min-spaces-inside-empty: -1
    max-spaces-inside-empty: -1

Examples

With brackets: {forbid: true}

the following code snippet would PASS:
```
object:
  - 1
  - 2
  - abc
```
the following code snippet would FAIL:
```
object: [ 1, 2, abc ]
```
With brackets: {forbid: non-empty}

the following code snippet would PASS:
```
object: []
```
the following code snippet would FAIL:
```
object: [ 1, 2, abc ]
```
With brackets: {min-spaces-inside: 0, max-spaces-inside: 0}

the following code snippet would PASS:
```
object: [1, 2, abc]
```
the following code snippet would FAIL:
```
object: [ 1, 2, abc ]
```
With brackets: {min-spaces-inside: 1, max-spaces-inside: 3}

the following code snippet would PASS:
```
object: [ 1, 2, abc ]
```
the following code snippet would PASS:
```
object: [ 1, 2, abc   ]
```
the following code snippet would FAIL:
```
object: [    1, 2, abc   ]
```
the following code snippet would FAIL:
```
object: [1, 2, abc ]
```
With brackets: {min-spaces-inside-empty: 0, max-spaces-inside-empty: 0}

the following code snippet would PASS:
```
object: []
```
the following code snippet would FAIL:
```
object: [ ]
```
With brackets: {min-spaces-inside-empty: 1, max-spaces-inside-empty: -1}

the following code snippet would PASS:
```
object: [         ]
```
the following code snippet would FAIL:
```
object: []
```

colons ¶

Use this rule to control the number of spaces before and after colons (:).

Options

max-spaces-before defines the maximal number of spaces allowed before colons (use -1 to disable).
max-spaces-after defines the maximal number of spaces allowed after colons (use -1 to disable).

Default values (when enabled)

rules:
  colons:
    max-spaces-before: 0
    max-spaces-after: 1

Examples

With colons: {max-spaces-before: 0, max-spaces-after: 1}

the following code snippet would PASS:
```
object:
  - a
  - b
key: value
```
With colons: {max-spaces-before: 1}

the following code snippet would PASS:
```
object :
  - a
  - b
```
the following code snippet would FAIL:
```
object  :
  - a
  - b
```
With colons: {max-spaces-after: 2}

the following code snippet would PASS:
```
first:  1
second: 2
third:  3
```
the following code snippet would FAIL:
```
first: 1
2nd:   2
third: 3
```

commas ¶

Use this rule to control the number of spaces before and after commas (,).

Options

max-spaces-before defines the maximal number of spaces allowed before commas (use -1 to disable).
min-spaces-after defines the minimal number of spaces required after commas.
max-spaces-after defines the maximal number of spaces allowed after commas (use -1 to disable).

Default values (when enabled)

rules:
  commas:
    max-spaces-before: 0
    min-spaces-after: 1
    max-spaces-after: 1

Examples

With commas: {max-spaces-before: 0}

the following code snippet would PASS:

strange var:
  [10, 20, 30, {x: 1, y: 2}]

the following code snippet would FAIL:

strange var:
  [10, 20 , 30, {x: 1, y: 2}]

With commas: {max-spaces-before: 2}

the following code snippet would PASS:
```
strange var:
  [10  , 20 , 30,  {x: 1  , y: 2}]
```

With commas: {max-spaces-before: -1}

the following code snippet would PASS:

strange var:
  [10,
   20   , 30
   ,   {x: 1, y: 2}]

With commas: {min-spaces-after: 1, max-spaces-after: 1}

the following code snippet would PASS:
```
strange var:
  [10, 20, 30, {x: 1, y: 2}]
```
the following code snippet would FAIL:
```
strange var:
  [10, 20,30,   {x: 1,   y: 2}]
```
With commas: {min-spaces-after: 1, max-spaces-after: 3}

the following code snippet would PASS:
```
strange var:
  [10, 20,  30,  {x: 1,   y: 2}]
```
With commas: {min-spaces-after: 0, max-spaces-after: 1}

the following code snippet would PASS:
```
strange var:
  [10, 20,30, {x: 1, y: 2}]
```

comments ¶

Use this rule to control the position and formatting of comments.

Options

Use require-starting-space to require a space character right after the #. Set to true to enable, false to disable.
Use ignore-shebangs to ignore a shebang at the beginning of the file when require-starting-space is set.
min-spaces-from-content is used to visually separate inline comments from content. It defines the minimal required number of spaces between a comment and its preceding content.

Default values (when enabled)

rules:
  comments:
    require-starting-space: true
    ignore-shebangs: true
    min-spaces-from-content: 2

Examples

With comments: {require-starting-space: true}

the following code snippet would PASS:
```
# This sentence
# is a block comment
```
the following code snippet would PASS:
```
##############################
## This is some documentation
```
the following code snippet would FAIL:
```
#This sentence
#is a block comment
```
With comments: {min-spaces-from-content: 2}

the following code snippet would PASS:
```
x = 2 ^ 127 - 1  # Mersenne prime number
```
the following code snippet would FAIL:
```
x = 2 ^ 127 - 1 # Mersenne prime number
```

comments-indentation ¶

Use this rule to force comments to be indented like content.

Examples

With comments-indentation: {}

the following code snippet would PASS:

# Fibonacci
[0, 1, 1, 2, 3, 5]

the following code snippet would FAIL:

  # Fibonacci
[0, 1, 1, 2, 3, 5]

the following code snippet would PASS:

list:
    - 2
    - 3
    # - 4
    - 5

the following code snippet would FAIL:

list:
    - 2
    - 3
#    - 4
    - 5

the following code snippet would PASS:

# This is the first object
obj1:
  - item A
  # - item B
# This is the second object
obj2: []

the following code snippet would PASS:

# This sentence
# is a block comment

the following code snippet would FAIL:

# This sentence
 # is a block comment

document-end ¶

Use this rule to require or forbid the use of document end marker (...).

Options

Set present to true when the document end marker is required, or to false when it is forbidden.

Default values (when enabled)

rules:
  document-end:
    present: true

Examples

With document-end: {present: true}

the following code snippet would PASS:

---
this:
  is: [a, document]
...
---
- this
- is: another one
...

the following code snippet would FAIL:

---
this:
  is: [a, document]
---
- this
- is: another one
...

With document-end: {present: false}

the following code snippet would PASS:

---
this:
  is: [a, document]
---
- this
- is: another one

the following code snippet would FAIL:

---
this:
  is: [a, document]
...
---
- this
- is: another one

document-start ¶

Use this rule to require or forbid the use of document start marker (---).

Options

Set present to true when the document start marker is required, or to false when it is forbidden.

Default values (when enabled)

rules:
  document-start:
    present: true

Examples

With document-start: {present: true}

the following code snippet would PASS:

---
this:
  is: [a, document]
---
- this
- is: another one

the following code snippet would FAIL:

this:
  is: [a, document]
---
- this
- is: another one

With document-start: {present: false}

the following code snippet would PASS:
```
this:
  is: [a, document]
...
```
the following code snippet would FAIL:
```
---
this:
  is: [a, document]
...
```

empty-lines ¶

Use this rule to set a maximal number of allowed consecutive blank lines.

Options

max defines the maximal number of empty lines allowed in the document.
max-start defines the maximal number of empty lines allowed at the beginning of the file. This option takes precedence over max.
max-end defines the maximal number of empty lines allowed at the end of the file. This option takes precedence over max.

Default values (when enabled)

rules:
  empty-lines:
    max: 2
    max-start: 0
    max-end: 0

Examples

With empty-lines: {max: 1}

the following code snippet would PASS:

- foo:
    - 1
    - 2

- bar: [3, 4]

the following code snippet would FAIL:

- foo:
    - 1
    - 2


- bar: [3, 4]

empty-values ¶

Use this rule to prevent nodes with empty content, that implicitly result in null values.

Options

Use forbid-in-block-mappings to prevent empty values in block mappings.
Use forbid-in-flow-mappings to prevent empty values in flow mappings.

Default values (when enabled)

rules:
  empty-values:
    forbid-in-block-mappings: true
    forbid-in-flow-mappings: true

Examples

With empty-values: {forbid-in-block-mappings: true}

the following code snippets would PASS:

some-mapping:
  sub-element: correctly indented

explicitly-null: null

the following code snippets would FAIL:

some-mapping:
sub-element: incorrectly indented

implicitly-null:

With empty-values: {forbid-in-flow-mappings: true}

the following code snippet would PASS:
```
{prop: null}
{a: 1, b: 2, c: 3}
```
the following code snippets would FAIL:
```
{prop: }
```
```
{a: 1, b:, c: 3}
```

Use this rule to limit the permitted values for floating-point numbers. YAML permits three classes of float expressions: approximation to real numbers, positive and negative infinity and “not a number”.

Options

Use require-numeral-before-decimal to require floats to start with a numeral (ex 0.0 instead of .0).
Use forbid-scientific-notation to forbid scientific notation.
Use forbid-nan to forbid NaN (not a number) values.
Use forbid-inf to forbid infinite values.

Default values (when enabled)

rules:
  float-values:
    forbid-inf: false
    forbid-nan: false
    forbid-scientific-notation: false
    require-numeral-before-decimal: false

Examples

With float-values: {require-numeral-before-decimal: true}

the following code snippets would PASS:
```
anemometer:
  angle: 0.0
```
the following code snippets would FAIL:
```
anemometer:
  angle: .0
```
With float-values: {forbid-scientific-notation: true}

the following code snippets would PASS:
```
anemometer:
  angle: 0.00001
```
the following code snippets would FAIL:
```
anemometer:
  angle: 10e-6
```
With float-values: {forbid-nan: true}

the following code snippets would FAIL:
```
anemometer:
  angle: .NaN
```

With float-values: {forbid-inf: true}
the following code snippets would FAIL:
anemometer:
  angle: .inf

hyphens ¶

Use this rule to control the number of spaces after hyphens (-).

Options

max-spaces-after defines the maximal number of spaces allowed after hyphens.

Default values (when enabled)

rules:
  hyphens:
    max-spaces-after: 1

Examples

With hyphens: {max-spaces-after: 1}

the following code snippet would PASS:

- first list:
    - a
    - b
- - 1
  - 2
  - 3

the following code snippet would FAIL:

-  first list:
     - a
     - b

the following code snippet would FAIL:

- - 1
  -  2
  - 3

With hyphens: {max-spaces-after: 3}

the following code snippet would PASS:
```
-   key
-  key2
- key42
```
the following code snippet would FAIL:
```
-    key
-   key2
-  key42
```

indentation ¶

Use this rule to control the indentation.

Options

spaces defines the indentation width, in spaces. Set either to an integer (e.g. 2 or 4, representing the number of spaces in an indentation level) or to consistent to allow any number, as long as it remains the same within the file.
indent-sequences defines whether block sequences should be indented or not (when in a mapping, this indentation is not mandatory – some people perceive the - as part of the indentation). Possible values: true, false, whatever and consistent. consistent requires either all block sequences to be indented, or none to be. whatever means either indenting or not indenting individual block sequences is OK.
check-multi-line-strings defines whether to lint indentation in multi-line strings. Set to true to enable, false to disable.

Default values (when enabled)

rules:
  indentation:
    spaces: consistent
    indent-sequences: true
    check-multi-line-strings: false

Examples

With indentation: {spaces: 1}

the following code snippet would PASS:

history:
 - name: Unix
   date: 1969
 - name: Linux
   date: 1991
nest:
 recurse:
  - haystack:
     needle

With indentation: {spaces: 4}

the following code snippet would PASS:

history:
    - name: Unix
      date: 1969
    - name: Linux
      date: 1991
nest:
    recurse:
        - haystack:
              needle

the following code snippet would FAIL:

history:
  - name: Unix
    date: 1969
  - name: Linux
    date: 1991
nest:
  recurse:
    - haystack:
        needle

With indentation: {spaces: consistent}

the following code snippet would PASS:

history:
   - name: Unix
     date: 1969
   - name: Linux
     date: 1991
nest:
   recurse:
      - haystack:
           needle

the following code snippet would FAIL:

some:
  Russian:
      dolls

With indentation: {spaces: 2, indent-sequences: false}

the following code snippet would PASS:
```
list:
- flying
- spaghetti
- monster
```
the following code snippet would FAIL:
```
list:
  - flying
  - spaghetti
  - monster
```

With indentation: {spaces: 2, indent-sequences: whatever}

the following code snippet would PASS:

list:
- flying:
  - spaghetti
  - monster
- not flying:
    - spaghetti
    - sauce

With indentation: {spaces: 2, indent-sequences: consistent}

the following code snippet would PASS:

- flying:
  - spaghetti
  - monster
- not flying:
  - spaghetti
  - sauce

the following code snippet would FAIL:

- flying:
    - spaghetti
    - monster
- not flying:
  - spaghetti
  - sauce

With indentation: {spaces: 4, check-multi-line-strings: true}

the following code snippet would PASS:

Blaise Pascal:
    Je vous écris une longue lettre parce que
    je n'ai pas le temps d'en écrire une courte.

the following code snippet would PASS:

Blaise Pascal: Je vous écris une longue lettre parce que
               je n'ai pas le temps d'en écrire une courte.

the following code snippet would FAIL:

Blaise Pascal: Je vous écris une longue lettre parce que
  je n'ai pas le temps d'en écrire une courte.

the following code snippet would FAIL:

C code:
    void main() {
        printf("foo");
    }

the following code snippet would PASS:

C code:
    void main() {
    printf("bar");
    }

key-duplicates ¶

Use this rule to prevent multiple entries with the same key in mappings.

Examples

With key-duplicates: {}

the following code snippet would PASS:

- key 1: v
  key 2: val
  key 3: value
- {a: 1, b: 2, c: 3}

the following code snippet would FAIL:

- key 1: v
  key 2: val
  key 1: value

the following code snippet would FAIL:

- {a: 1, b: 2, b: 3}

the following code snippet would FAIL:

duplicated key: 1
"duplicated key": 2

other duplication: 1
? >-
    other
    duplication
: 2

key-ordering ¶

Use this rule to enforce alphabetical ordering of keys in mappings. The sorting order uses the Unicode code point number as a default. As a result, the ordering is case-sensitive and not accent-friendly (see examples below). This can be changed by setting the global locale option. This allows one to sort case and accents properly.

Examples

With key-ordering: {}

the following code snippet would PASS:

- key 1: v
  key 2: val
  key 3: value
- {a: 1, b: 2, c: 3}
- T-shirt: 1
  T-shirts: 2
  t-shirt: 3
  t-shirts: 4
- hair: true
  hais: true
  haïr: true
  haïssable: true

the following code snippet would FAIL:

- key 2: v
  key 1: val

the following code snippet would FAIL:

- {b: 1, a: 2}

the following code snippet would FAIL:

- T-shirt: 1
  t-shirt: 2
  T-shirts: 3
  t-shirts: 4

the following code snippet would FAIL:

- haïr: true
  hais: true

With global option locale: "en_US.UTF-8" and rule key-ordering: {}

as opposed to before, the following code snippet would now PASS:

- t-shirt: 1
  T-shirt: 2
  t-shirts: 3
  T-shirts: 4
- hair: true
  haïr: true
  hais: true
  haïssable: true

line-length ¶

Use this rule to set a limit to lines length.

Options

max defines the maximal (inclusive) length of lines.
allow-non-breakable-words is used to allow non breakable words (without spaces inside) to overflow the limit. This is useful for long URLs, for instance. Use true to allow, false to forbid.
allow-non-breakable-inline-mappings implies allow-non-breakable-words and extends it to also allow non-breakable words in inline mappings.

Default values (when enabled)

rules:
  line-length:
    max: 80
    allow-non-breakable-words: true
    allow-non-breakable-inline-mappings: false

Examples

With line-length: {max: 70}

the following code snippet would PASS:

long sentence:
  Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do
  eiusmod tempor incididunt ut labore et dolore magna aliqua.

the following code snippet would FAIL:

long sentence:
  Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod
  tempor incididunt ut labore et dolore magna aliqua.

With line-length: {max: 60, allow-non-breakable-words: true}

the following code snippet would PASS:

this:
  is:
    - a:
        http://localhost/very/very/very/very/very/very/very/very/long/url

# this comment is too long,
# but hard to split:
# http://localhost/another/very/very/very/very/very/very/very/very/long/url

the following code snippet would FAIL:

- this line is waaaaaaaaaaaaaay too long but could be easily split...

and the following code snippet would also FAIL:

- foobar: http://localhost/very/very/very/very/very/very/very/very/long/url

With line-length: {max: 60, allow-non-breakable-words: true, allow-non-breakable-inline-mappings: true}

the following code snippet would PASS:
```
- foobar: http://localhost/very/very/very/very/very/very/very/very/long/url
```

With line-length: {max: 60, allow-non-breakable-words: false}

the following code snippet would FAIL:

this:
  is:
    - a:
        http://localhost/very/very/very/very/very/very/very/very/long/url

new-line-at-end-of-file ¶

Use this rule to require a new line character (\n) at the end of files.

The POSIX standard requires the last line to end with a new line character. All UNIX tools expect a new line at the end of files. Most text editors use this convention too.

new-lines ¶

Use this rule to force the type of new line characters.

Options

Set type to unix to enforce UNIX-typed new line characters (\n), set type to dos to enforce DOS-typed new line characters (\r\n), or set type to platform to infer the type from the system running yamllint (\n on POSIX / UNIX / Linux / Mac OS systems or \r\n on DOS / Windows systems).

Default values (when enabled)

rules:
  new-lines:
    type: unix

octal-values ¶

Use this rule to prevent values with octal numbers. In YAML, numbers that start with 0 are interpreted as octal, but this is not always wanted. For instance 010 is the city code of Beijing, and should not be converted to 8.

Options

Use forbid-implicit-octal to prevent numbers starting with 0.
Use forbid-explicit-octal to prevent numbers starting with 0o.

Default values (when enabled)

rules:
  octal-values:
    forbid-implicit-octal: true
    forbid-explicit-octal: true

Examples

With octal-values: {forbid-implicit-octal: true}

the following code snippets would PASS:
```
user:
  city-code: '010'
```
the following code snippets would PASS:
```
user:
  city-code: 010,021
```
the following code snippets would FAIL:
```
user:
  city-code: 010
```
With octal-values: {forbid-explicit-octal: true}

the following code snippets would PASS:
```
user:
  city-code: '0o10'
```
the following code snippets would FAIL:
```
user:
  city-code: 0o10
```

quoted-strings ¶

Use this rule to forbid any string values that are not quoted, or to prevent quoted strings without needing it. You can also enforce the type of the quote used.

Options

quote-type defines allowed quotes: single, double or any (default).
required defines whether using quotes in string values is required (true, default) or not (false), or only allowed when really needed (only-when-needed).
extra-required is a list of PCRE regexes to force string values to be quoted, if they match any regex. This option can only be used with required: false and required: only-when-needed.
extra-allowed is a list of PCRE regexes to allow quoted string values, even if required: only-when-needed is set.
allow-quoted-quotes allows (true) using disallowed quotes for strings with allowed quotes inside. Default false.

Note: Multi-line strings (with | or >) will not be checked.

Default values (when enabled)

rules:
  quoted-strings:
    quote-type: any
    required: true
    extra-required: []
    extra-allowed: []
    allow-quoted-quotes: false

Examples

With quoted-strings: {quote-type: any, required: true}

the following code snippet would PASS:
```
foo: "bar"
bar: 'foo'
number: 123
boolean: true
```
the following code snippet would FAIL:
```
foo: bar
```

With quoted-strings: {quote-type: single, required: only-when-needed}

the following code snippet would PASS:

foo: bar
bar: foo
not_number: '123'
not_boolean: 'true'
not_comment: '# comment'
not_list: '[1, 2, 3]'
not_map: '{a: 1, b: 2}'

the following code snippet would FAIL:

foo: 'bar'

With quoted-strings: {required: false, extra-required: [^http://, ^ftp://]}

the following code snippet would PASS:
```
- localhost
- "localhost"
- "http://localhost"
- "ftp://localhost"
```
the following code snippet would FAIL:
```
- http://localhost
- ftp://localhost
```
With quoted-strings: {required: only-when-needed, extra-allowed: [^http://, ^ftp://], extra-required: [QUOTED]}

the following code snippet would PASS:
```
- localhost
- "http://localhost"
- "ftp://localhost"
- "this is a string that needs to be QUOTED"
```
the following code snippet would FAIL:
```
- "localhost"
- this is a string that needs to be QUOTED
```
With quoted-strings: {quote-type: double, allow-quoted-quotes: false}

the following code snippet would PASS:
```
foo: "bar\"baz"
```
the following code snippet would FAIL:
```
foo: 'bar"baz'
```
With quoted-strings: {quote-type: double, allow-quoted-quotes: true}

the following code snippet would PASS:
```
foo: 'bar"baz'
```

trailing-spaces ¶

Use this rule to forbid trailing spaces at the end of lines.

Examples

With trailing-spaces: {}

the following code snippet would PASS:

this document doesn't contain
any trailing
spaces

the following code snippet would FAIL:

this document contains     
trailing spaces
on lines 1 and 3         

truthy ¶

Use this rule to forbid non-explicitly typed truthy values other than allowed ones (by default: true and false), for example YES or off.

This can be useful to prevent surprises from YAML parsers transforming [yes, FALSE, Off] into [true, false, false] or {y: 1, yes: 2, on: 3, true: 4, True: 5} into {y: 1, true: 5}.

Options

allowed-values defines the list of truthy values which will be ignored during linting. The default is ['true', 'false'], but can be changed to any list containing: 'TRUE', 'True', 'true', 'FALSE', 'False', 'false', 'YES', 'Yes', 'yes', 'NO', 'No', 'no', 'ON', 'On', 'on', 'OFF', 'Off', 'off'.
check-keys disables verification for keys in mappings. By default, truthy rule applies to both keys and values. Set this option to false to prevent this.

Default values (when enabled)

rules:
  truthy:
    allowed-values: ['true', 'false']
    check-keys: true

Examples

With truthy: {}

the following code snippet would PASS:

boolean: true

object: {"True": 1, 1: "True"}

"yes":  1
"on":   2
"True": 3

 explicit:
   string1: !!str True
   string2: !!str yes
   string3: !!str off
   encoded: !!binary |
              True
              OFF
              pad==  # this decodes as 'N»8Qii'
   boolean1: !!bool true
   boolean2: !!bool "false"
   boolean3: !!bool FALSE
   boolean4: !!bool True
   boolean5: !!bool off
   boolean6: !!bool NO

the following code snippet would FAIL:

object: {True: 1, 1: True}

the following code snippet would FAIL:

yes:  1
on:   2
True: 3

With truthy: {allowed-values: ["yes", "no"]}

the following code snippet would PASS:
```
- yes
- no
- "true"
- 'false'
- foo
- bar
```
the following code snippet would FAIL:
```
- true
- false
- on
- off
```
With truthy: {check-keys: false}

the following code snippet would PASS:
```
yes:  1
on:   2
true: 3
```
the following code snippet would FAIL:
```
yes:  Yes
on:   On
true: True
```