yamllint

https://yamllint.readthedocs.io/en/stable/
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### Install yamllint from source

Source: https://yamllint.readthedocs.io/en/stable/_sources/quickstart.rst.txt

Install yamllint from source by building the package and then installing it using pip.

```bash
python -m build
pip install --user dist/yamllint-*.tar.gz
```

--------------------------------

### Install yamllint from source

Source: https://yamllint.readthedocs.io/en/stable/quickstart.html

Install yamllint from source by first building the package and then installing it using pip. This installs it for the current user.

```bash
python -m build
pip install --user dist/yamllint-*.tar.gz

```

--------------------------------

### Install yamllint on OpenBSD

Source: https://yamllint.readthedocs.io/en/stable/quickstart.html

Use this command to install yamllint on OpenBSD systems.

```bash
doas pkg_add py-yamllint

```

--------------------------------

### Install yamllint on FreeBSD

Source: https://yamllint.readthedocs.io/en/stable/quickstart.html

Use this command to install yamllint on FreeBSD systems.

```bash
pkg install py-yamllint

```

--------------------------------

### Install yamllint on OpenBSD

Source: https://yamllint.readthedocs.io/en/stable/_sources/quickstart.rst.txt

Install the py-yamllint package on OpenBSD using doas.

```sh
doas pkg_add py-yamllint
```

--------------------------------

### Install yamllint using pip

Source: https://yamllint.readthedocs.io/en/stable/quickstart.html

Install yamllint using pip, the Python package manager. This installs it for the current user.

```bash
pip install --user yamllint

```

--------------------------------

### yamllint output example (standard)

Source: https://yamllint.readthedocs.io/en/stable/quickstart.html

This is an example of the default output format when yamllint is run from a terminal. Colors are not displayed here.

```text
file.yml
  1:4       error    trailing spaces  (trailing-spaces)
  4:4       error    wrong indentation: expected 4 but found 3  (indentation)
  5:4       error    duplication of key "id-00042" in mapping  (key-duplicates)
  6:6       warning  comment not indented like content  (comments-indentation)
  12:6      error    too many spaces after hyphen  (hyphens)
  15:12     error    too many spaces before comma  (commas)

other-file.yaml
  1:1       warning  missing document start "---"  (document-start)
  6:81      error    line too long (87 > 80 characters)  (line-length)
  10:1      error    too many blank lines (4 > 2)  (empty-lines)
  11:4      error    too many spaces inside braces  (braces)


```

--------------------------------

### Indentation Rule with spaces: 2, indent-sequences: false (Pass Example)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This configuration passes when 'spaces' is 2 and 'indent-sequences' is false. It allows block sequences to start at the same indentation level as their parent mapping.

```yaml
list:
- flying
- spaghetti
- monster

```

--------------------------------

### Install yamllint on Fedora/CentOS

Source: https://yamllint.readthedocs.io/en/stable/quickstart.html

Use this command to install yamllint on Fedora or CentOS systems. EPEL repository is required on CentOS.

```bash
sudo dnf install yamllint

```

--------------------------------

### Install yamllint on Alpine Linux

Source: https://yamllint.readthedocs.io/en/stable/quickstart.html

Use this command to install yamllint on Alpine Linux systems.

```bash
pkg add yamllint

```

--------------------------------

### Install yamllint on Debian/Ubuntu

Source: https://yamllint.readthedocs.io/en/stable/quickstart.html

Use this command to install yamllint on Debian 8+ or Ubuntu 16.04+ systems.

```bash
sudo apt-get install yamllint

```

--------------------------------

### Install yamllint on Mac OS

Source: https://yamllint.readthedocs.io/en/stable/quickstart.html

Use this command to install yamllint on Mac OS 10.11+ using Homebrew.

```bash
brew install yamllint

```

--------------------------------

### Configure document-start rule

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Set 'present' to true to require the document start marker, or false to forbid it. This configuration enables the rule.

```yaml
rules:
  document-start:
    present: true

```

--------------------------------

### Indentation Rule with spaces: 4 (Pass Example)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Shows a YAML structure that passes the indentation rule when 'spaces' is set to 4. This example illustrates consistent 4-space indentation for nested mappings and sequences.

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

```

--------------------------------

### Indentation Rule with spaces: consistent (Pass Example)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example demonstrates a YAML structure that passes the indentation rule when 'spaces' is set to 'consistent'. It shows that any indentation is allowed as long as it remains the same within the file.

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

```

--------------------------------

### Indentation Rule with spaces: 2, indent-sequences: consistent (Pass Example)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example passes when 'spaces' is 2 and 'indent-sequences' is 'consistent'. It requires all block sequences to be either indented or not indented consistently.

```yaml
- flying:
  - spaghetti
  - monster
- not flying:
  - spaghetti
  - sauce

```

--------------------------------

### Pass example for quoted-strings with consistent quote type

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example passes when 'quoted-strings' requires a consistent quote type, and all strings use single quotes.

```yaml
foo: 'bar'
baz: 'quux'


```

--------------------------------

### Running yamllint from Python

Source: https://yamllint.readthedocs.io/en/stable/development.html

This example demonstrates how to use the `yamllint.linter.run` function to lint a YAML file programmatically. It shows how to load configuration and iterate over the linting problems found.

```APIDOC
## Running yamllint from Python

### Description
Basic example of running the linter from Python.

### Code
```python
import yamllint.config
import yamllint.linter

yaml_config = yamllint.config.YamlLintConfig("extends: default")
for p in yamllint.linter.run(open("example.yaml", "r"), yaml_config):
    print(p.desc, p.line, p.rule)
```
```

--------------------------------

### key-duplicates: Pass example with simple keys

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This snippet demonstrates a YAML structure that passes the `key-duplicates` rule when no specific options are set.

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

```

--------------------------------

### key-ordering: Pass example with correctly ordered keys

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This snippet demonstrates YAML structures that pass the `key-ordering` rule when no specific options are set, showing correct alphabetical and case-sensitive ordering.

```yaml
- 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

```

--------------------------------

### Require Starting Space in Comments

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Demonstrates passing cases for the 'require-starting-space' option, where a space follows the '#' character.

```yaml
# This sentence
# is a block comment

```

```yaml
##############################
## This is some documentation

```

--------------------------------

### Pass example for quoted-strings with any quote type

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example passes when 'quoted-strings' is configured to allow any quote type and requires strings to be quoted. It shows valid quoted strings and unquoted non-string types.

```yaml
foo: "bar"
bar: 'foo'
number: 123
boolean: true


```

--------------------------------

### Document with document-start marker (present: false)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example shows an invalid YAML document when the 'document-start' rule forbids the '---' marker.

```yaml
---
this:
  is: [a, document]
...

```

--------------------------------

### Pass example for quoted-strings with check-keys: true and extra-required

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example passes when 'quoted-strings' is configured to check keys and requires strings containing colons to be quoted. The key '"foo:bar"' is correctly quoted.

```yaml
"foo:bar": baz


```

--------------------------------

### Complex Path Exclusion Example

Source: https://yamllint.readthedocs.io/en/stable/configuration.html

Demonstrates a more complex .gitignore-style path exclusion configuration, including inclusion rules with the '!' prefix. This allows for nuanced control over ignored files.

```yaml
# For all rules
ignore: |
  *.dont-lint-me.yaml
  /bin/
  !/bin/*.lint-me-anyway.yaml

extends: default

rules:
  key-duplicates:
    ignore: |
      generated
      *.template.yaml
  trailing-spaces:
    ignore: |
      *.ignore-trailing-spaces.yaml
      ascii-art/*
```

--------------------------------

### Document without document-start marker (present: false)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example shows a valid YAML document when the 'document-start' rule forbids the '---' marker.

```yaml
this:
  is: [a, document]
...

```

--------------------------------

### Indentation Rule with spaces: 2, indent-sequences: consistent (Fail Example)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example fails when 'spaces' is 2 and 'indent-sequences' is 'consistent'. It shows inconsistent indentation of block sequences, where one is indented and another is not.

```yaml
- flying:
    - spaghetti
    - monster
- not flying:
  - spaghetti
  - sauce

```

--------------------------------

### Indentation Rule with spaces: 2, indent-sequences: whatever (Pass Example)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This configuration passes when 'spaces' is 2 and 'indent-sequences' is 'whatever'. It allows for a mix of indented and non-indented block sequences.

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

```

--------------------------------

### Pass example for quoted-strings with only-when-needed, extra-allowed, and extra-required

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example passes when 'quoted-strings' requires quotes only when needed, allows specific URL patterns, and enforces quotes for strings matching 'QUOTED'. It shows unquoted strings, allowed URLs, and a specifically required quoted string.

```yaml
- localhost
- "http://localhost"
- "ftp://localhost"
- "this is a string that needs to be QUOTED"


```

--------------------------------

### Indentation Rule with spaces: consistent (Fail Example)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example shows a YAML structure that fails the indentation rule when 'spaces' is set to 'consistent'. It highlights inconsistent indentation levels within the same file.

```yaml
some:
  Russian:
      dolls

```

--------------------------------

### Fail example for quoted-strings with check-keys: true and extra-required

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example fails when 'quoted-strings' is configured to check keys and requires strings containing colons to be quoted. The key 'foo:bar' violates this rule.

```yaml
foo:bar: baz


```

--------------------------------

### Validate Colon Spacing (0 before, 1 after)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Example of YAML that passes with max-spaces-before: 0 and max-spaces-after: 1.

```yaml
object:
  - a
  - b
key: value

```

--------------------------------

### Pass example for quoted-strings with required: false and extra-required

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example passes when 'quoted-strings' does not require quotes by default but enforces them for strings not matching specific URL patterns. It shows unquoted strings and correctly quoted URLs.

```yaml
- localhost
- "localhost"
- "http://localhost"
- "ftp://localhost"


```

--------------------------------

### Fail example for quoted-strings with any quote type

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example fails when 'quoted-strings' requires strings to be quoted, as 'bar' is an unquoted string value.

```yaml
foo: bar


```

--------------------------------

### Fail example for quoted-strings with single quotes and only-when-needed

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example fails when 'quoted-strings' requires single quotes only when needed, as 'bar' is a string that does not require quoting in this configuration.

```yaml
foo: 'bar'


```

--------------------------------

### Truthy Rule: Pass Example (Default Config)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

A YAML document that passes the `truthy` rule with default settings, demonstrating acceptable boolean representations and keys.

```yaml
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»ž8Qii'
   boolean1: !!bool true
   boolean2: !!bool "false"
   boolean3: !!bool FALSE
   boolean4: !!bool True
   boolean5: !!bool off
   boolean6: !!bool NO


```

--------------------------------

### key-ordering: Pass example with ignored keys

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This snippet demonstrates a YAML structure that passes the `key-ordering` rule when the `ignored-keys` option is used to exclude specific keys from the ordering check.

```yaml
- a:
  b:
  name: ignored
  first-name: ignored
  c:
  d:

```

--------------------------------

### Document without document-start marker (present: true)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example shows an invalid YAML document when the 'document-start' rule requires the '---' marker.

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

```

--------------------------------

### Fail Case for Starting Space in Comments

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Shows a failing case for 'require-starting-space' where a comment lacks a space after the '#'.

```yaml
#This sentence
#is a block comment

```

--------------------------------

### Indentation Rule with spaces: 2, indent-sequences: false (Fail Example)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example fails when 'spaces' is 2 and 'indent-sequences' is false. It shows an incorrectly indented block sequence, where the sequence items are indented relative to the parent mapping.

```yaml
list:
  - flying
  - spaghetti
  - monster

```

--------------------------------

### Indentation Rule with spaces: 4, check-multi-line-strings: true (Fail Example 1)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example fails when 'spaces' is 4 and 'check-multi-line-strings' is true. It shows a multi-line string with incorrect indentation for its subsequent lines.

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


```

--------------------------------

### Indentation Rule with spaces: 4, check-multi-line-strings: true (Pass Example 1)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example passes with 4-space indentation and multi-line string checking enabled. It shows a correctly indented multi-line string.

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


```

--------------------------------

### Fail example for quoted-strings with required: false and extra-required

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example fails when 'quoted-strings' does not require quotes by default but enforces them for strings matching specific URL patterns. The unquoted URLs violate this rule.

```yaml
- http://localhost
- ftp://localhost


```

--------------------------------

### Indentation Rule with spaces: 4, check-multi-line-strings: true (Pass Example 2)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example also passes with 4-space indentation and multi-line string checking enabled. It demonstrates a single-line string that is correctly aligned with subsequent lines of a multi-line string.

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


```

--------------------------------

### Indentation Rule with spaces: 4 (Fail Example)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Illustrates a YAML structure that fails the indentation rule when 'spaces' is set to 4. This example highlights incorrect indentation, specifically with a 2-space indent for nested elements.

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

```

--------------------------------

### Indentation Rule with spaces: 1 (Pass Example)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Demonstrates a YAML structure that passes the indentation rule when 'spaces' is set to 1. This allows for a single space indentation for nested elements.

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

```

--------------------------------

### key-ordering: Fail example with case-sensitive ordering

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This snippet demonstrates a YAML structure that fails the `key-ordering` rule due to incorrect case-sensitive ordering.

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

```

--------------------------------

### Fail example for quoted-strings with consistent quote type

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example fails when 'quoted-strings' requires a consistent quote type, as it uses both single and double quotes for string values.

```yaml
foo: 'bar'
baz: "quux"


```

--------------------------------

### Fail example for quoted-strings with only-when-needed, extra-allowed, and extra-required

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example fails when 'quoted-strings' requires quotes only when needed but enforces them for strings matching 'QUOTED'. The unquoted string 'this is a string that needs to be QUOTED' violates this.

```yaml
- "localhost"
- this is a string that needs to be QUOTED


```

--------------------------------

### key-ordering: Fail example with incorrectly ordered keys

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This snippet demonstrates a YAML structure that fails the `key-ordering` rule due to keys not being in alphabetical order.

```yaml
- key 2: v
  key 1: val

```

--------------------------------

### Pass example for quoted-strings with single quotes and only-when-needed

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example passes when 'quoted-strings' requires single quotes only when needed. It shows unquoted strings and strings quoted with single quotes, including those that might be misinterpreted as other types.

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


```

--------------------------------

### Run yamllint Linter from Python

Source: https://yamllint.readthedocs.io/en/stable/development.html

Use the yamllint Python module to lint YAML files programmatically. This example shows how to load a configuration and iterate over linting problems.

```python
import yamllint.config
import yamllint.linter

yaml_config = yamllint.config.YamlLintConfig("extends: default")
for p in yamllint.linter.run(open("example.yaml", "r"), yaml_config):
    print(p.desc, p.line, p.rule)

```

--------------------------------

### Fail Comma Spacing (space before comma)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Example of YAML that fails with max-spaces-before: 0 due to a space before a comma.

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

```

--------------------------------

### Indentation Rule with spaces: 4, check-multi-line-strings: true (Pass Example 3)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example passes with 4-space indentation and multi-line string checking enabled. It shows a C code block with correct indentation within a multi-line string context.

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


```

--------------------------------

### Validate Comma Spacing (0 spaces before)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Example of YAML that passes with max-spaces-before: 0. No spaces are allowed before commas.

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

```

--------------------------------

### Pass example for quoted-strings with double quotes and allow-quoted-quotes: false

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example passes when 'quoted-strings' requires double quotes and does not allow quoted quotes within strings. It shows a valid string using escaped double quotes.

```yaml
foo: "bar\"baz"


```

--------------------------------

### Minimal GitHub Actions workflow for yamllint

Source: https://yamllint.readthedocs.io/en/stable/_sources/integration.rst.txt

A basic GitHub Actions workflow that checks out code, installs yamllint, and runs it on YAML files. yamllint automatically detects GitHub Actions and uses the appropriate output format.

```yaml
---
on: push

jobs:
  lint:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3

      - name: Install yamllint
        run: pip install yamllint

      - name: Lint YAML files
        run: yamllint .

```

--------------------------------

### key-ordering: Fail example with accent-sensitive ordering

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This snippet demonstrates a YAML structure that fails the `key-ordering` rule due to incorrect accent-sensitive ordering.

```yaml
- haïr: true
  hais: true

```

--------------------------------

### Fail example for quoted-strings with double quotes and allow-quoted-quotes: false

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example fails when 'quoted-strings' requires double quotes and does not allow quoted quotes within strings. It shows a string using single quotes which is disallowed.

```yaml
foo: 'bar"baz'


```

--------------------------------

### key-ordering: Pass example with locale option

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This snippet demonstrates YAML structures that pass the `key-ordering` rule when the global `locale` option is set to 'en_US.UTF-8', allowing for proper case and accent-insensitive sorting.

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

```

--------------------------------

### Validate Comma Spacing (2 spaces before)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Example of YAML that passes with max-spaces-before: 2. Allows up to two spaces before commas.

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

```

--------------------------------

### key-duplicates: Pass example with merge keys

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This snippet demonstrates a YAML structure that passes the `key-duplicates` rule when `forbid-duplicated-merge-keys` is `true` and merge keys are used correctly.

```yaml
anchor_one: &anchor_one
  one: one
anchor_two: &anchor_two
  two: two
anchor_reference:
  <<: [*anchor_one, *anchor_two]

```

--------------------------------

### Fail Colon Spacing (too many spaces before)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Example of YAML that fails with max-spaces-before: 1 due to multiple spaces before the colon.

```yaml
object  :
  - a
  - b

```

--------------------------------

### Validate Colon Spacing (1 before)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Example of YAML that passes with max-spaces-before: 1. Ensure only one space precedes the colon.

```yaml
object :
  - a
  - b

```

--------------------------------

### Indentation Rule with spaces: 4, check-multi-line-strings: true (Fail Example 2)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example fails when 'spaces' is 4 and 'check-multi-line-strings' is true. It demonstrates a C code block with incorrect indentation within a multi-line string context.

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


```

--------------------------------

### Validate Comma Spacing (0-1 spaces after)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Example of YAML that passes with min-spaces-after: 0 and max-spaces-after: 1. Allows 0 or 1 space after commas.

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

```

--------------------------------

### Pass example for forbid-duplicated-anchors

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This YAML snippet passes when `forbid-duplicated-anchors` is `true` because each anchor (`&anchor1`, `&anchor2`) is unique.

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

```

--------------------------------

### Validate Comma Spacing (1-3 spaces after)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Example of YAML that passes with min-spaces-after: 1 and max-spaces-after: 3. Allows 1 to 3 spaces after commas.

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

```

--------------------------------

### Document with document-end marker (present: true)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example shows a valid YAML document when the 'document-end' rule requires the '...' marker.

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

```

--------------------------------

### Fail Colon Spacing (incorrect spaces after)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Example of YAML that fails with max-spaces-after: 2 due to inconsistent spacing after colons.

```yaml
first: 1
2nd:   2
third: 3

```

--------------------------------

### Fail example for forbid-duplicated-anchors

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This YAML snippet fails when `forbid-duplicated-anchors` is `true` because the anchor `&anchor` is defined twice.

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

```

--------------------------------

### Validate Comma Spacing (no spaces before)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Example of YAML that passes with max-spaces-before: -1. Disables the rule for spaces before commas.

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

```

--------------------------------

### Fail Comma Spacing (incorrect spaces after)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Example of YAML that fails with min-spaces-after: 1 and max-spaces-after: 1 due to inconsistent spacing after commas.

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

```

--------------------------------

### Configure Comments Rule

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Enables the comments rule with specific options for starting spaces, ignoring shebangs, and minimum spaces from content.

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

```

--------------------------------

### Validate Colon Spacing (2 spaces after)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Example of YAML that passes with max-spaces-after: 2. Allows up to two spaces after the colon.

```yaml
first:  1
second: 2
third:  3

```

--------------------------------

### Max Spaces After Hyphen (3)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Allows up to three spaces after a hyphen. Shows examples that pass and fail this configuration.

```yaml
-   key
-  key2
- key42

```

```yaml
-    key
-   key2
-  key42

```

--------------------------------

### key-duplicates: Fail example with repeated keys

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This snippet demonstrates a YAML structure that fails the `key-duplicates` rule due to repeated keys within a mapping.

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

```

--------------------------------

### Truthy Rule: Fail Example (Default Config)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

A YAML document that fails the `truthy` rule with default settings due to the key 'True' in the object.

```yaml
object: {True: 1, 1: True}


```

--------------------------------

### Allow Empty Flow Sequences Only

Source: https://yamllint.readthedocs.io/en/stable/rules.html

With `forbid: non-empty`, only empty flow sequences are permitted. This example shows a valid empty flow sequence.

```yaml
object: []

```

--------------------------------

### Line Length Rule with Max 70 Characters

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example demonstrates a line-length rule configured with a maximum of 70 characters. The provided 'PASS' snippet adheres to this limit, while the 'FAIL' snippet exceeds it.

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

```

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

```

--------------------------------

### Pass example for forbid-undeclared-aliases

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This YAML snippet passes when `forbid-undeclared-aliases` is set to `true` because the alias `*anchor` correctly references a declared anchor.

```yaml
---
- &anchor
  foo: bar
- *anchor

```

--------------------------------

### Select Relaxed Configuration via Command Line

Source: https://yamllint.readthedocs.io/en/stable/_sources/configuration.rst.txt

Use the -d option with 'relaxed' to apply the relaxed configuration.

```bash
yamllint -d relaxed file.yml
```

--------------------------------

### key-ordering: Fail example with incorrectly ordered keys in flow style

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This snippet demonstrates a YAML structure that fails the `key-ordering` rule due to keys not being in alphabetical order within a flow-style mapping.

```yaml
- {b: 1, a: 2}

```

--------------------------------

### key-duplicates: Fail example with repeated keys in flow style

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This snippet demonstrates a YAML structure that fails the `key-duplicates` rule due to repeated keys in a flow-style mapping.

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

```

--------------------------------

### Document without document-end marker (present: false)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example shows a valid YAML document when the 'document-end' rule forbids the '...' marker.

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

```

--------------------------------

### Default Truthy Rule Configuration

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This is the default configuration for the `truthy` rule, which ignores 'true' and 'false' values and checks keys. The first example passes with this configuration.

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


```

--------------------------------

### Fail example for forbid-undeclared-aliases (undeclared alias with merge)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This YAML snippet fails when `forbid-undeclared-aliases` is `true` because the merge key `<<: *unknown` references an anchor that is not declared.

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

```

--------------------------------

### key-duplicates: Fail example with multiple merge keys

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This snippet demonstrates a YAML structure that fails the `key-duplicates` rule when `forbid-duplicated-merge-keys` is `true` and multiple merge keys are used for the same mapping.

```yaml
anchor_one: &anchor_one
  one: one
anchor_two: &anchor_two
  two: two
anchor_reference:
  <<: *anchor_one
  <<: *anchor_two

```

--------------------------------

### Lint with a custom configuration file

Source: https://yamllint.readthedocs.io/en/stable/_sources/quickstart.rst.txt

Specify a custom linting configuration file using the -c option.

```bash
yamllint -c ~/myconfig file.yaml
```

--------------------------------

### Run yamllint with a custom configuration file

Source: https://yamllint.readthedocs.io/en/stable/quickstart.html

Specify a custom configuration file using the '-c' option when running yamllint. This allows for project-specific linting rules.

```bash
yamllint -c ~/myconfig file.yaml

```

--------------------------------

### Truthy Rule: Pass Example (YAML 1.2)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This YAML 1.2 document passes the `truthy` rule because 'yes' and 'on' are not considered truthy in YAML 1.2, and 'true' is explicitly allowed by default.

```yaml
%YAML 1.2
---
yes:  1
on:   2
true: 3


```

--------------------------------

### key-duplicates: Fail example with different key representations

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This snippet demonstrates a YAML structure that fails the `key-duplicates` rule due to keys that are duplicates despite different representations (string vs. quoted string, string vs. block scalar).

```yaml
duplicated key: 1
"duplicated key": 2

other duplication: 1
? >-
    other
    duplication
: 2

```

--------------------------------

### Arcanist .arclint configuration for yamllint

Source: https://yamllint.readthedocs.io/en/stable/_sources/integration.rst.txt

Configure yamllint to run with 'arc lint' by defining it as a 'script-and-regex' linter in your .arclint file. This setup specifies the command to run and the regex to parse its output, including line number, severity, message, and name.

```json
{
  "linters": {
    "yamllint": {
      "type": "script-and-regex",
      "script-and-regex.script": "yamllint",
      "script-and-regex.regex": "/^(?P<line>\\d+):(?P<offset>\\d+) +(?P<severity>warning|error) +(?P<message>.*) +\\((?P<name>.*)\\)$/m",
      "include": "(\\.(yml|yaml)$)"
    }
  }
}

```

--------------------------------

### Extend Default Configuration: Modify Rules

Source: https://yamllint.readthedocs.io/en/stable/_sources/configuration.rst.txt

Customize 'line-length' to warn at 80 characters and adjust 'indentation' for sequences.

```yaml
extends: default

rules:
  # 80 chars should be enough, but don't fail if a line is longer
  line-length:
    max: 80
    level: warning

  # accept both     key:
  #                   - item
  #
  # and             key:
  #                 - item
  indentation:
    indent-sequences: whatever
```

--------------------------------

### Specify Custom Configuration File

Source: https://yamllint.readthedocs.io/en/stable/_sources/configuration.rst.txt

Use the -c option to point yamllint to a custom configuration file.

```bash
yamllint -c /path/to/myconfig file-to-lint.yaml
```

--------------------------------

### Extend Default Configuration: Warning for Line Length and Indentation

Source: https://yamllint.readthedocs.io/en/stable/configuration.html

Extend the default configuration to set 'line-length' as a warning and adjust 'indentation' for sequences. This allows for more flexible rule enforcement.

```yaml
extends: default

rules:
  # 80 chars should be enough, but don't fail if a line is longer
  line-length:
    max: 80
    level: warning

  # accept both     key:
  #                   - item
  #
  # and             key:
  #                 - item
  indentation:
    indent-sequences: whatever

```

--------------------------------

### Pass Custom Configuration Data via Command Line

Source: https://yamllint.readthedocs.io/en/stable/_sources/configuration.rst.txt

Use the -d option with a serialized YAML object to pass custom configuration data directly.

```bash
yamllint -d "{extends: relaxed, rules: {line-length: {max: 120}}}" file.yaml
```

--------------------------------

### Specify Custom Configuration File

Source: https://yamllint.readthedocs.io/en/stable/configuration.html

Use the -c option to point yamllint to a custom configuration file. This allows for tailored linting rules.

```bash
yamllint -c /path/to/myconfig file-to-lint.yaml

```

--------------------------------

### Basic yamllint usage

Source: https://yamllint.readthedocs.io/en/stable/quickstart.html

Run yamllint on one or more YAML files. Specify the files to be linted as arguments.

```bash
yamllint file.yml other-file.yaml

```

--------------------------------

### Configure YAML File Extensions

Source: https://yamllint.readthedocs.io/en/stable/configuration.html

Set the `yaml-files` option to specify which file extensions yamllint should consider as YAML files. The default includes common extensions like '.yaml' and '.yml'.

```yaml
yaml-files:
  - '*.yaml'
  - '*.yml'
  - '.yamllint'
```

--------------------------------

### Fail example for forbid-unused-anchors

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This YAML snippet fails when `forbid-unused-anchors` is `true` because the anchor `&anchor` is declared but never used by any alias.

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

```

--------------------------------

### Require Numeral Before Decimal in Floats

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Enforces that float values must start with a numeral, like `0.0`, instead of `.0`.

```yaml
anemometer:
  angle: 0.0

```

```yaml
anemometer:
  angle: .0

```

--------------------------------

### Run yamllint Linter from Python

Source: https://yamllint.readthedocs.io/en/stable/_sources/development.rst.txt

Use the yamllint Python module to lint a YAML file with a custom configuration. Requires importing config and linter modules.

```python
import yamllint.config
import yamllint.linter

yaml_config = yamllint.config.YamlLintConfig("extends: default")
for p in yamllint.linter.run(open("example.yaml", "r"), yaml_config):
    print(p.desc, p.line, p.rule)
```

--------------------------------

### List Files to be Processed

Source: https://yamllint.readthedocs.io/en/stable/configuration.html

Use the `--list-files` command-line option to see the exact list of files yamllint will process without actually linting them. This is useful for verifying configuration.

```bash
yamllint --list-files .
```

--------------------------------

### Document with document-end marker (present: false)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example shows an invalid YAML document when the 'document-end' rule forbids the '...' marker.

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

```

--------------------------------

### Fail example for forbid-undeclared-aliases (undeclared alias)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This YAML snippet fails when `forbid-undeclared-aliases` is `true` because the alias `*unknown` references an anchor that is not declared.

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

```

--------------------------------

### Configure document-end rule

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Set 'present' to true to require the document end marker, or false to forbid it. This configuration enables the rule.

```yaml
rules:
  document-end:
    present: true

```

--------------------------------

### Use parsable output format

Source: https://yamllint.readthedocs.io/en/stable/_sources/quickstart.rst.txt

Use the -f parsable argument for machine-readable output, suitable for syntax highlighting in text editors.

```bash
yamllint -f parsable file.yml
```

--------------------------------

### Minimum Spaces for Inline Comments

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Illustrates passing cases for 'min-spaces-from-content', ensuring at least two spaces separate inline comments from code.

```yaml
x = 2 ^ 127 - 1  # Mersenne prime number

```

--------------------------------

### Minimal GitHub Actions workflow for yamllint

Source: https://yamllint.readthedocs.io/en/stable/integration.html

A basic GitHub Actions workflow to lint YAML files. yamllint automatically detects GitHub Actions and uses the appropriate output format. You can also force the GitHub Actions output format using `yamllint --format github`.

```yaml
---
on: push  # yamllint disable-line rule:truthy

jobs:
  lint:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3

      - name: Install yamllint
        run: pip install yamllint

      - name: Lint YAML files
        run: yamllint .

```

--------------------------------

### Document without document-end marker (present: true)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example shows an invalid YAML document when the 'document-end' rule requires the '...' marker.

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

```

--------------------------------

### GitLab CI/CD stage for yamllint with Code Quality report

Source: https://yamllint.readthedocs.io/en/stable/_sources/integration.rst.txt

This GitLab CI/CD configuration runs yamllint, formats the output as a parsable report, and transforms it into a Code Climate-compatible JSON file for GitLab's Code Quality feature. Ensure the 'reports' directory is created and artifacts are configured correctly.

```yaml
---
lint:
  stage: lint
  script:
    - pip install yamllint
    - mkdir reports
    - >
      yamllint -f parsable . | tee >(awk '
      BEGIN {FS = ":"; ORS="\n"; first=1}
      {
          gsub(/^[ \t]+|[ \t]+$|"/, "", $4);
          match($4, /^\[(warning|error)\](.*)\(.*\)$/, a);
          sev = (a[1] == "error" ? "major" : "minor");
          if (first) {
              first=0;
              printf("[");
          } else {
              printf(",");
          }
          printf("{\"location\":{\"path\":\"%s\",\"lines\":{\"begin\":%s,\"end\":%s}},\"severity\":\"%s\",\"check_name\":\"%s\",\"categories\":[\"Style\"],\"type\":\"issue\",\"description\":\"%s\"}", $1, $2, $3, sev, a[3], a[2]);
      }
      END { if (!first) printf("]\n"); }') > reports/codequality.json
  artifacts:
    when: always
    paths:
      - reports
    expire_in: 1 week
    reports:
      codequality: reports/codequality.json

```

--------------------------------

### Configure Comma Spacing Rules

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Set rules for spaces before and after commas. max-spaces-before and max-spaces-after use -1 to disable.

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

```

--------------------------------

### Use Relaxed Configuration

Source: https://yamllint.readthedocs.io/en/stable/configuration.html

Choose the 'relaxed' configuration using the -d option when running yamllint. This applies a more lenient set of linting rules.

```bash
yamllint -d relaxed file.yml

```

--------------------------------

### Custom Configuration via Command Line Argument

Source: https://yamllint.readthedocs.io/en/stable/configuration.html

Pass custom configuration data directly to yamllint using the '-d' or '--config-data' option. This is not recommended for complex configurations.

```bash
yamllint -d "{extends: relaxed, rules: {line-length: {max: 120}}}" file.yaml

```

--------------------------------

### Truthy Rule: Fail Example (YAML 1.1)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This YAML 1.1 document fails the `truthy` rule because it uses 'yes', 'on', and 'True' which are not explicitly allowed by default.

```yaml
%YAML 1.1
---
yes:  1
on:   2
True: 3


```

--------------------------------

### Forbid Flow Sequences with Brackets Rule

Source: https://yamllint.readthedocs.io/en/stable/rules.html

When `forbid: true`, flow sequences using brackets are disallowed. This example shows a valid structure without flow sequences.

```yaml
object:
  - 1
  - 2
  - abc

```

--------------------------------

### Integrate yamllint with pre-commit

Source: https://yamllint.readthedocs.io/en/stable/_sources/integration.rst.txt

Add this configuration to your .pre-commit-config.yaml to use yamllint with pre-commit. Update the 'rev' to your desired release version and specify a custom .yamllint configuration file using the 'args' attribute.

```yaml
---
# Update the rev variable with the release version that you want, from the yamllint repo
# You can pass your custom .yamllint with args attribute.
repos:
  - repo: https://github.com/adrienverge/yamllint.git
    rev: v1.29.0
    hooks:
      - id: yamllint
        args: [--strict, -c=/path/to/.yamllint]

```

--------------------------------

### Configure float-values Rule

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Default configuration for the `float-values` rule. Adjust options to control float formatting.

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

```

--------------------------------

### Prevent Implicit Octal Values

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Disallows numbers starting with '0' to prevent them from being interpreted as octal. This rule is useful when '010' should represent a city code and not the number 8.

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

```

--------------------------------

### Ignore Paths with List

Source: https://yamllint.readthedocs.io/en/stable/configuration.html

Configure the `ignore` key with a list of paths to exclude files and directories. This also uses .gitignore-style path patterns.

```yaml
extends: default

ignore:
  - /this/specific/file.yaml
  - all/this/directory/
  - '*.template.yaml'
```

--------------------------------

### Configure Maximum Empty Lines (yamllint)

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Set the maximum number of consecutive blank lines allowed in a YAML document. Options `max-start` and `max-end` can override `max` for the beginning and end of the file, respectively.

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

```

--------------------------------

### Fail Case: Missing Required Spaces Inside Brackets

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This snippet fails when `min-spaces-inside: 1` because it lacks the required minimum space after the opening bracket.

```yaml
object: [1, 2, abc ]

```

--------------------------------

### yamllint parsable output format

Source: https://yamllint.readthedocs.io/en/stable/quickstart.html

Use the '-f parsable' arguments for an output format that can be parsed by machines, useful for text editor integration.

```text
file.yml:6:2: [warning] missing starting space in comment (comments)
file.yml:57:1: [error] trailing spaces (trailing-spaces)
file.yml:60:3: [error] wrong indentation: expected 4 but found 2 (indentation)


```

--------------------------------

### View Default yamllint Configuration

Source: https://yamllint.readthedocs.io/en/stable/_sources/configuration.rst.txt

This is the default configuration file used by yamllint when no custom configuration is provided.

```yaml
---
```

--------------------------------

### Forbid Flow Mappings with Braces Rule

Source: https://yamllint.readthedocs.io/en/stable/rules.html

When `braces: {forbid: true}`, flow mappings denoted by surrounding braces are forbidden. This example shows a passing snippet without flow mappings and a failing snippet with them.

```yaml
object:
  key1: 4
  key2: 8

```

```yaml
object: { key1: 4, key2: 8 }

```

--------------------------------

### Forbid Non-Empty Flow Mappings with Braces Rule

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Using `braces: {forbid: non-empty}` forbids all flow mappings except for empty ones. This example demonstrates a passing empty flow mapping and a failing non-empty one.

```yaml
object: {}

```

```yaml
object: { key1: 4, key2: 8 }

```

--------------------------------

### Configure key-ordering rule

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Default configuration for the key-ordering rule. The `ignored-keys` option takes a list of PCRE regexes to skip specific keys during ordering checks.

```yaml
rules:
  key-ordering:
    ignored-keys: []

```

--------------------------------

### Ignore Files from Multiple Files

Source: https://yamllint.readthedocs.io/en/stable/configuration.html

Specify multiple files (e.g., `.gitignore` and `.yamlignore`) for path exclusions by providing a list to the `ignore-from-file` option.

```yaml
ignore-from-file: [.gitignore, .yamlignore]
```

--------------------------------

### Line Length Rule with Max 60 and Disallow Non-breakable Words

Source: https://yamllint.readthedocs.io/en/stable/rules.html

This example shows a line-length rule with a maximum of 60 characters and explicitly disallowing non-breakable words. The 'FAIL' snippet demonstrates that a long URL, even if it's a non-breakable word, will cause a failure.

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

```

--------------------------------

### Fail Case for Minimum Spaces in Comments

Source: https://yamllint.readthedocs.io/en/stable/rules.html

Shows a failing case for 'min-spaces-from-content' where an inline comment does not have the required minimum spaces.

```yaml
x = 2 ^ 127 - 1 # Mersenne prime number

```

--------------------------------

### Lint all YAML files in a directory

Source: https://yamllint.readthedocs.io/en/stable/quickstart.html

Use this command to lint all YAML files within the current directory.

```bash
yamllint .

```

--------------------------------

### Lint YAML stream from standard input

Source: https://yamllint.readthedocs.io/en/stable/quickstart.html

Pipe YAML content to yamllint using standard input. The hyphen '-' indicates that input should be read from stdin.

```bash
echo -e 'this: is\nvalid: YAML' | yamllint - 

```

--------------------------------

### Ignore Paths with Bulk String

Source: https://yamllint.readthedocs.io/en/stable/configuration.html

Configure the `ignore` key with a bulk string to exclude files and directories. This uses .gitignore-style path patterns for flexible exclusion.

```yaml
extends: default

ignore: |
  /this/specific/file.yaml
  all/this/directory/
  *.template.yaml
```
Tokens:
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