《Terraform 101 从入门到实践》 Functions函数

喜欢ヅ旅行 2024-03-27 16:03 91阅读 0赞

## **Terraform的函数** ##

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

Terraform为了让大家在表达式上可以更加灵活方便地进行计算，提供了大量的内置函数（Function）。目前并不支持自定义函数，只能使用Terraform自带的。使用函数的格式也很简单，直接写函数名+参数即可。如下面的函数为取最大值：

> max(34, 45, 232, 25)
    232

这里把函数单独列成一章不是因为它很难理解，而因为它很常用，值得把这些函数梳理一下，以便查询使用吧。

## **数值计算函数** ##

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

绝对值abs：

> abs(5)
    5
    > abs(-3.1415926)
    3.1415926
    > abs(0)
    0

[返回大于等于该数][Link 1]值的最小整数：

> ceil(3)
    3
    > ceil(3.1)
    4
    > ceil(2.9)
    3

小于等于该数值的最大整数：

> floor(6)
    6
    > floor(6.9)
    6
    > floor(5.34)
    5

对数函数：

> log(16, 2)
    4
    > log(9, 3)
    2.0000000000000004

指数函数：

> pow(6, 2)
    36
    > pow(6, 1)
    6
    > pow(6, 0)
    1

最大值、最小值：

> max(2, 98,  75, 4)
    98
    > min(2, 98,  75, 4)
    2

字符串转换成整数，第二个参数为进制：

> parseint("16", 10)
    16
    > parseint("16", 16)
    22
    > parseint("FF", 16)
    255
    > parseint("1010", 2)
    10

信号量函数：

> signum(6)
    1
    > signum(-6)
    -1
    > signum(0)
    0

## **字符串函数** ##

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

删去换行，在从文件中读取文本时非常有用：

> chomp("www.pkslow.com")
    "www.pkslow.com"
    > chomp("www.pkslow.com\n")
    "www.pkslow.com"
    > chomp("www.pkslow.com\n\n")
    "www.pkslow.com"
    > chomp("www.pkslow.com\n\n\r")
    "www.pkslow.com"
    > chomp("www.pkslow.com\n\n\ra")
    <<EOT
    www.pkslow.com
    
    a
    EOT

格式化输出：

> format("Hi, %s!", "Larry")
    "Hi, Larry!"
    
    > format("My name is %s, I'm %d", "Larry", 18)
    "My name is Larry, I'm 18"
    
    > format("The reuslt is %.2f", 3)
    "The reuslt is 3.00"
    
    > format("The reuslt is %.2f", 3.1415)
    "The reuslt is 3.14"
    
    > format("The reuslt is %8.2f", 3.1415)
    "The reuslt is     3.14"

遍历格式化列表：

> formatlist("My name is %s, I'm %d %s.", ["Larry", "Jeremy", "Tailor"], [18, 28, 33], "in 2022")
    tolist([
      "My name is Larry, I'm 18 in 2022.",
      "My name is Jeremy, I'm 28 in 2022.",
      "My name is Tailor, I'm 33 in 2022.",
    ])

参数可以是List，还可以是单个变量。

字符串连接：

> join(".", ["www", "pkslow", "com"])
    "www.pkslow.com"
    > join(", ", ["Larry", "Pkslow", "JJ"])
    "Larry, Pkslow, JJ"

大小写字母转换：

> lower("Larry Nanhua DENG")
    "larry nanhua deng"
    > upper("Larry Nanhua DENG")
    "LARRY NANHUA DENG"

首字母大写：

> title("larry")
    "Larry"

替换：

> replace("www.larrydpk.com", "larrydpk", "pkslow")
    "www.pkslow.com"
    > replace("hello larry", "/la.*y/", "pkslow")
    "hello pkslow"

分割：

> split(".", "www.pklow.com")
    tolist([
      "www",
      "pklow",
      "com",
    ])

反转：

> strrev("pkslow")
    "wolskp"

截取：

> substr("Larry Deng", 0, 5)
    "Larry"
    > substr("Larry Deng", -4, -1)
    "Deng"

去除头尾某些特定字符，注意这里只要有对应字符就会删除：

> trim("?!what?!!!!!", "?!")
    "what"
    > trim("abaaaaabbLarry Dengaab", "ab")
    "Larry Deng"

去除头尾特定字符串，注意与上面的区别：

> trimsuffix("?!what?!!!!!", "!!!")
    "?!what?!!"
    > trimprefix("?!what?!!!!!", "?!")
    "what?!!!!!"

去除头尾的空格、换行等空串：

> trimspace(" Larry Deng \n\r")
    "Larry Deng"

正则匹配，下面的例子是匹配第一个和匹配所有：

> regex("[a-z\\.]+", "2021www.pkslow.com2022larry deng 31415926")
    "www.pkslow.com"
    > regexall("[a-z\\.]+", "2021www.pkslow.com2022larry deng 31415926")
    tolist([
      "www.pkslow.com",
      "larry",
      "deng",
    ])

更多正则匹配语法可参考：[https://www.terraform.io/language/functions/regex][https_www.terraform.io_language_functions_regex]

## **集合类函数** ##

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

alltrue：判断列表是否全为真，空列表直接返回true。只能是bool类型或者对应的字符串。

> alltrue([true, "true"])
    true
    > alltrue([true, "true", false])
    false
    > alltrue([])
    true
    > alltrue([1])
    ╷
    │ Error: Invalid function argument
    │ 
    │   on <console-input> line 1:
    │   (source code not available)
    │ 
    │ Invalid value for "list" parameter: element 0: bool required.

anytrue：判断列表是否有真，只要有一个为真就返回true。空列表为false。

> anytrue([true])
    true
    > anytrue([true, false])
    true
    > anytrue([false, false])
    false
    > anytrue([])
    false

chunklist分片：根据分片数来对列表进行切分。

> chunklist(["www", "pkslow", "com", "Larry", "Deng"], 3)
    tolist([
      tolist([
        "www",
        "pkslow",
        "com",
      ]),
      tolist([
        "Larry",
        "Deng",
      ]),
    ])

coalesce返回第一个非空元素：

> coalesce("", "a", "b")
    "a"
    > coalesce("", "", "b")
    "b"

coalescelist返回第一个非空列表：

> coalescelist([], ["pkslow"])
    [
      "pkslow",
    ]

从字符串列表里把空的去掉：

> compact(["", "www", "", "pkslow", "com"])
    tolist([
      "www",
      "pkslow",
      "com",
    ])

concat连接多个列表：

> concat([1, 2, 3], [4, 5, 6])
    [
      1,
      2,
      3,
      4,
      5,
      6,
    ]

contains判断是否存在某个元素：

> contains(["www", "pkslow", "com"], "pkslow")
    true
    > contains(["www", "pkslow", "com"], "Larry")
    false

distinct去除重复元素：

> distinct([1, 2, 2, 1, 3, 8, 1, 10])
    tolist([
      1,
      2,
      3,
      8,
      10,
    ])

element获取列表的某个元素：

> element(["a", "b", "c"], 1)
    "b"
    > element(["a", "b", "c"], 2)
    "c"
    > element(["a", "b", "c"], 3)
    "a"
    > element(["a", "b", "c"], 4)
    "b"

flatten把内嵌的列表都展开成一个列表：

> flatten([1, 2, 3, [1], [[6]]])
    [
      1,
      2,
      3,
      1,
      6,
    ]

index获取列表中的元素的索引值：

> index(["www", "pkslow", "com"], "pkslow")
    1

keys获取map的所有key值：

> keys({name="Larry", age=18, webSite="www.pkslow.com"})
    [
      "age",
      "name",
      "webSite",
    ]

values获取map的value值：

> values({name="Larry", age=18, webSite="www.pkslow.com"})
    [
      18,
      "Larry",
      "www.pkslow.com",
    ]

length获取字符串、列表、Map等的长度：

> length([])
    0
    > length(["pkslow"])
    1
    > length(["pkslow", "com"])
    2
    > length({pkslow = "com"})
    1
    > length("pkslow")
    6

lookup(map, key, default)根据key值在map中找到对应的value值，如果没有则返回默认值：

> lookup({name = "Larry", age = 18}, "age", 1)
    18
    > lookup({name = "Larry", age = 18}, "myAge", 1)
    1

matchkeys(valueslist, keyslist, searchset)对key值进行匹配。匹配到key值后，返回对应的Value值。

> matchkeys(["a", "b", "c", "d"], [1, 2, 3, 4], [2, 4])
    tolist([
      "b",
      "d",
    ])

merge合并Map，key相同的会被最后的覆盖：

> merge({name = "Larry", webSite = "pkslow.com"}, {age = 18})
    {
      "age" = 18
      "name" = "Larry"
      "webSite" = "pkslow.com"
    }
    > merge({name = "Larry", webSite = "pkslow.com"}, {age = 18}, {age = 13})
    {
      "age" = 13
      "name" = "Larry"
      "webSite" = "pkslow.com"
    }

one取集合的一个元素，如果为空则返回null；如果只有一个元素，则返回该元素；如果多个元素，则报错：

> one([])
    null
    > one(["pkslow"])
    "pkslow"
    > one(["pkslow", "com"])
    ╷
    │ Error: Invalid function argument
    │ 
    │   on <console-input> line 1:
    │   (source code not available)
    │ 
    │ Invalid value for "list" parameter: must be a list, set, or tuple value with either zero or one elements.
    ╵

range生成顺序列表：

range(max)
    range(start, limit)
    range(start, limit, step)
    
    > range(3)
    tolist([
      0,
      1,
      2,
    ])
    > range(1, 6)
    tolist([
      1,
      2,
      3,
      4,
      5,
    ])
    > range(1, 6, 2)
    tolist([
      1,
      3,
      5,
    ])

reverse反转列表：

> reverse([1, 2, 3, 4])
    [
      4,
      3,
      2,
      1,
    ]

setintersection对set求交集：

> setintersection([1, 2, 3], [2, 3, 4], [2, 3, 6])
    toset([
      2,
      3,
    ])

setproduct列出所有组合可能：

> setproduct(["Larry", "Harry"], ["Deng", "Potter"])
    tolist([
      [
        "Larry",
        "Deng",
      ],
      [
        "Larry",
        "Potter",
      ],
      [
        "Harry",
        "Deng",
      ],
      [
        "Harry",
        "Potter",
      ],
    ])

setsubtract：set的减法

> setsubtract([1, 2, 3], [3, 4])
    toset([
      1,
      2,
    ])
    
    # 求不同
    > setunion(setsubtract(["a", "b", "c"], ["a", "c", "d"]), setsubtract(["a", "c", "d"], ["a", "b", "c"]))
    [
      "b",
      "d",
    ]

setunion：set的加法

> setunion([1, 2, 3], [3, 4])
    toset([
      1,
      2,
      3,
      4,
    ])

slice(list, startindex, endindex)截取列表部分，包括startindex，但不包括endindex：

> slice(["a", "b", "c", "d", "e"], 1, 4)
    [
      "b",
      "c",
      "d",
    ]

sort对列表中的字符串进行排序，要注意如果输入的是数字，会先转化为字符串再排序：

> sort(["larry", "pkslow", "com", "deng"])
    tolist([
      "com",
      "deng",
      "larry",
      "pkslow",
    ])
    > sort([3, 6, 1, 9, 12, 79, 22])
    tolist([
      "1",
      "12",
      "22",
      "3",
      "6",
      "79",
      "9",
    ])

sum求和：

> sum([3, 1.2, 9, 17.3, 2.2])
    32.7

transpose对Map的key和value进行换位：

> transpose({"a" = ["1", "2"], "b" = ["2", "3"]})
    tomap({
      "1" = tolist([
        "a",
      ])
      "2" = tolist([
        "a",
        "b",
      ])
      "3" = tolist([
        "b",
      ])
    })

zipmap根据key和value的列表按一对一关系生成Map：

> zipmap(["age", "name"], [18, "Larry Deng"])
    {
      "age" = 18
      "name" = "Larry Deng"
    }

## **加密解密** ##

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

Base64：

> base64encode("pkslow")
    "cGtzbG93"
    > base64decode("cGtzbG93")
    "pkslow"
    > textencodebase64("pkslow", "UTF-8")
    "cGtzbG93"
    > textdecodebase64("cGtzbG93", "UTF-8")
    "pkslow"

csv文本解析：

> csvdecode("seq,name,age\n1,larry,18\n2,pkslow,3\n3,Jeremy,29")
    tolist([
      {
        "age" = "18"
        "name" = "larry"
        "seq" = "1"
      },
      {
        "age" = "3"
        "name" = "pkslow"
        "seq" = "2"
      },
      {
        "age" = "29"
        "name" = "Jeremy"
        "seq" = "3"
      },
    ])

Json解析：

> jsonencode({"name"="Larry", "age"=18})
    "{\"age\":18,\"name\":\"Larry\"}"
    > jsondecode("{\"age\":18,\"name\":\"Larry\"}")
    {
      "age" = 18
      "name" = "Larry"
    }

URL：

> urlencode("Larry Deng/a/:/./@")
    "Larry+Deng%2Fa%2F%3A%2F.%2F%40"

YAML：

> yamlencode({"a":"b", "c":"d"})
    "a": "b"
    "c": "d"
    
    > yamlencode({"foo":[1, 2, 3], "bar": "baz"})
    "bar": "baz"
    "foo":
    - 1
    - 2
    - 3
    
    > yamlencode({"foo":[1, {"a":"b","c":"d"}, 3], "bar": "baz"})
    "bar": "baz"
    "foo":
    - 1
    - "a": "b"
      "c": "d"
    - 3
    > yamldecode("hello: world")
    {
      "hello" = "world"
    }
    
    > yamldecode("true")
    true
    
    > yamldecode("{a: &foo [1, 2, 3], b: *foo}")
    {
      "a" = [
        1,
        2,
        3,
      ]
      "b" = [
        1,
        2,
        3,
      ]
    }

文件处理：

获取绝对路径：

> abspath(path.root)
    "/Users/larry"

获取路径中的目录，或者是文件名：

> dirname("/home/larry/soft/terraform")
    "/home/larry/soft"
    > dirname("/home/larry/soft/terraform/")
    "/home/larry/soft/terraform"
    > basename("/home/larry/soft/terraform")
    "terraform"
    > basename("/home/larry/soft/terraform/")
    "terraform"

判断文件是否存在，并获取文件内容：

> fileexists("/Users/larry/.bash_profile")
    true
    > file("/Users/larry/.bash_profile")
    > filebase64("/Users/larry/.bash_profile")

根据模式匹配所有文件：

> fileset("/Users/larry", "*.bash*")
    toset([
      ".bash_history",
      ".bash_profile",
      ".bash_profile.backup",
    ])

[templatefile(path, vars)模板化文件][templatefile_path_ vars]：指定文件和变量，把变量值替换掉模板中的变量。

## **时间函数** ##

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

获取当前时间，并格式化显示，格式请参考：[https://www.terraform.io/language/functions/formatdate][https_www.terraform.io_language_functions_formatdate]

> formatdate("YYYY-MM-DD hh:mm:ss / D MMMM YYYY", timestamp())
    "2022-03-05 08:25:48 / 5 March 2022"
    > formatdate("EEEE, DD-MMM-YY hh:mm:ss ZZZ", "2018-01-02T23:12:01Z")
    "Tuesday, 02-Jan-18 23:12:01 UTC"

时间加减：

> timeadd(timestamp(), "24h")
    "2022-03-06T08:28:52Z"
    > timeadd(timestamp(), "-24h10m")
    "2022-03-04T08:19:08Z"

支持的单位有："ns", "us" (or "µs"), "ms", "s", "m", and "h".

## **其它** ##

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

加密：

> md5("www.pkslow.com")
    "97e164b60faf4d7875c2a8a5bc3f2245"

UUID：

> uuid()
    "049bf418-15d1-e034-28db-92945067dcf6"

IP：

> cidrsubnet("172.16.0.0/12", 4, 2)
    "172.18.0.0/16"

[Link 1]: http://51taorencai.com
[https_www.terraform.io_language_functions_regex]: https://www.terraform.io/language/functions/regex
[templatefile_path_ vars]: https://www.terraform.io/language/functions/templatefile
[https_www.terraform.io_language_functions_formatdate]: https://www.terraform.io/language/functions/formatdate