Kubernetes 之 YAML 语法

YAML 是一种非常简洁/强大/专门用来写配置文件的语言！

YAML 全称是 ”YAML Ain’t a Markup Language” 的递归缩写，该语言的设计参考了 JSON / XML 和 SDL 等语言,强调以数据为中心，简洁易读，编写简单。

YAML 语法特性

学过编程的人理解起来应该非常容易

语法特点

• 大小写敏感
• 通过缩进表示层级关系
• 禁止使用tab缩进，只能使用空格键
• 缩进的空格数目不重要，只要相同层级左对齐
• 使用#表示注释

# yaml
languages:
    - Ruby
    - Perl
    - Python
websites:
    YAML: yaml.org
    Ruby: ruby-lang.org
    Python: python.org
    Perl: use.perl.org

# Json
{
    languages: [
        'Ruby',
        'Perl',
        'Python'
    ],
    websites: {
        YAML: 'yaml.org',
        Ruby: 'ruby-lang.org',
        Python: 'python.org',
        Perl: 'use.perl.org'
    }
}

数据结构

• 对象: 键值对的字典 -数组: 一组按次序排列的列表 -纯量: 单个的且不可再分的值

# 纯量
hello

# 数组
- Cat
- Dog
- Goldfish

# 对象
animal: pets

• 引号区别
• 单引号(''): 特殊字符作为普通字符串处理

• 双引号(""): 特殊字符作为本身想表示的意思

  # 单引号
  name: 'Hi,\nTom'

双引号

name: "Hi,\nTom"

## 内置类型列表
# YAML允许使用个感叹号(!)强制转换数据类型
# 单叹号通常是自定义类型，双叹号是内置类型
money: !!str
123

date: !Boolean
true

YAML 中的纯量

纯量是最基本的且不可再分的值

• 字符串

# 不适用引号
name: Tom

# 使用单引号
name: 'Tom'

# 使用双引号
name: "Tom"

• 布尔值

debug: true
debug: false

• 数字

12       # 十进制整数
014      # 八进制整数
0xC      ＃十六进制整数
13.4     ＃浮点数
1.2e+34  ＃指数
.inf     ＃无穷大

• Null

date: ~
date: null

• 时间

# 使用iso-8601标准表示日期
date: 2018-01-01t16:59:43.10-05:00

YAML 特殊类型

日常使用中基本不会用到的类型

文本块

# 注意“|”与文本之间须另起一行
# 使用|标注的文本内容缩进表示的块，可以保留块中已有的回车换行
value: |
  hello
  world!

# 输出结果
# hello 换行 world！

# +表示保留文字块末尾的换行
# -表示删除字符串末尾的换行
value: |
hello

value: |-
hello

value: |+
hello

# 输出结果
# hello\n hello hello\n\n

# 注意“>”与文本之间的空格
# 使用>标注的文本内容缩进表示的块，将块中回车替换为空格最终连接成一行
value: > hello
world!

# 输出结果
# hello 空格 world！

锚点与引用

# 复制代码注意*引用部分不能追加内容
# 使用&定义数据锚点，即要复制的数据
# 使用*引用锚点数据，即数据的复制目的地
name: &a yaml
book: *a
books:
   - java
   - *a
   - python

# 输出结果
book： yaml
books：[java, yaml, python]

YAML 实例说明

光说不练假把式 => JS-Yaml 官网实例地址 https://nodeca.github.io/js-yaml

---
# Collection Types #############################################################
################################################################################

# http://yaml.org/type/map.html -----------------------------------------------#

map:
  # Unordered set of key: value pairs.
  Block style: !!map
    Clark: Evans
    Ingy: döt Net
    Oren: Ben-Kiki
  Flow style: !!map { Clark: Evans, Ingy: döt Net, Oren: Ben-Kiki }

# http://yaml.org/type/omap.html ----------------------------------------------#

omap:
  # Explicitly typed ordered map (dictionary).
  Bestiary: !!omap
    - aardvark: African pig-like ant eater. Ugly.
    - anteater: South-American ant eater. Two species.
    - anaconda: South-American constrictor snake. Scaly.
    # Etc.
  # Flow style
  Numbers: !!omap [one: 1, two: 2, three: 3]

# http://yaml.org/type/pairs.html ---------------------------------------------#

pairs:
  # Explicitly typed pairs.
  Block tasks: !!pairs
    - meeting: with team.
    - meeting: with boss.
    - break: lunch.
    - meeting: with client.
  Flow tasks: !!pairs [meeting: with team, meeting: with boss]

# http://yaml.org/type/set.html -----------------------------------------------#

set:
  # Explicitly typed set.
  baseball players: !!set
    ? Mark McGwire
    ? Sammy Sosa
    ? Ken Griffey
  # Flow style
  baseball teams: !!set { Boston Red Sox, Detroit Tigers, New York Yankees }

# http://yaml.org/type/seq.html -----------------------------------------------#

seq:
  # Ordered sequence of nodes
  Block style: !!seq
    - Mercury # Rotates - no light/dark sides.
    - Venus # Deadliest. Aptly named.
    - Earth # Mostly dirt.
    - Mars # Seems empty.
    - Jupiter # The king.
    - Saturn # Pretty.
    - Uranus # Where the sun hardly shines.
    - Neptune # Boring. No rings.
    - Pluto # You call this a planet?
  Flow style: !!seq [
      Mercury,
      Venus,
      Earth,
      Mars, # Rocks
      Jupiter,
      Saturn,
      Uranus,
      Neptune, # Gas
      Pluto,
    ] # Overrated

# Scalar Types #################################################################
################################################################################

# http://yaml.org/type/bool.html ----------------------------------------------#

bool:
  - true
  - True
  - TRUE
  - false
  - False
  - FALSE

# http://yaml.org/type/float.html ---------------------------------------------#

float:
  canonical: 6.8523015e+5
  exponentioal: 685.230_15e+03
  fixed: 685_230.15
  sexagesimal: 190:20:30.15
  negative infinity: -.inf
  not a number: .NaN

# http://yaml.org/type/int.html -----------------------------------------------#

int:
  canonical: 685230
  decimal: +685_230
  octal: 02472256
  hexadecimal: 0x_0A_74_AE
  binary: 0b1010_0111_0100_1010_1110
  sexagesimal: 190:20:30

# http://yaml.org/type/merge.html ---------------------------------------------#

merge:
  - &CENTER { x: 1, y: 2 }
  - &LEFT { x: 0, y: 2 }
  - &BIG { r: 10 }
  - &SMALL { r: 1 }

  # All the following maps are equal:

  - # Explicit keys
    x: 1
    y: 2
    r: 10
    label: nothing

  - # Merge one map
    <<: *CENTER
    r: 10
    label: center

  - # Merge multiple maps
    <<: [*CENTER, *BIG]
    label: center/big

  - # Override
    <<: [*BIG, *LEFT, *SMALL]
    x: 1
    label: big/left/small

# http://yaml.org/type/null.html ----------------------------------------------#

null:
  # This mapping has four keys,
  # one has a value.
  empty:
  canonical: ~
  english: null
  ~: null key
  # This sequence has five
  # entries, two have values.
  sparse:
    - ~
    - 2nd entry
    -
    - 4th entry
    - Null

# http://yaml.org/type/str.html -----------------------------------------------#

string: abcd

# http://yaml.org/type/timestamp.html -----------------------------------------#

timestamp:
  canonical: 2001-12-15T02:59:43.1Z
  valid iso8601: 2001-12-14t21:59:43.10-05:00
  space separated: 2001-12-14 21:59:43.10 -5
  no time zone (Z): 2001-12-15 2:59:43.10
  date (00:00:00Z): 2002-12-14

# JavaScript Specific Types ####################################################
################################################################################

# https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/RegExp

regexp:
  simple: !!js/regexp foobar
  modifiers: !!js/regexp /foobar/mi

# https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/undefined

undefined: !!js/undefined ~

# https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Function

function: !!js/function >
  function foobar() {
    return 'Wow! JS-YAML Rocks!';
  }

# Custom types #################################################################
################################################################################

# JS-YAML allows you to specify a custom YAML types for your structures.
# This is a simple example of custom constructor defined in `js/demo.js` for
# custom `!sexy` type:
#
# var SexyYamlType = new jsyaml.Type('!sexy', {
#   kind: 'sequence',
#   construct: function (data) {
#     return data.map(function (string) { return 'sexy ' + string; });
#   }
# });
#
# var SEXY_SCHEMA = jsyaml.Schema.create([ SexyYamlType ]);
#
# result = jsyaml.load(yourData, { schema: SEXY_SCHEMA });

foobar: !sexy
  - bunny
  - chocolate

作者: Escape
链接: https://www.escapelife.site/p...