github.com/anth0d/nomad@v0.0.0-20221214183521-ae3a0a2cad06/website/content/docs/job-specification/hcl2/functions/ipnet/cidrsubnets.mdx (about)

     1  ---
     2  layout: docs
     3  page_title: cidrsubnets - Functions - Configuration Language
     4  description: |-
     5    The cidrsubnets function calculates a sequence of consecutive IP address
     6    ranges within a particular CIDR prefix.
     7  ---
     8  
     9  # `cidrsubnets` Function
    10  
    11  `cidrsubnets` calculates a sequence of consecutive IP address ranges within
    12  a particular CIDR prefix.
    13  
    14  ```hcl
    15  cidrsubnets(prefix, newbits...)
    16  ```
    17  
    18  `prefix` must be given in CIDR notation, as defined in
    19  [RFC 4632 section 3.1](https://tools.ietf.org/html/rfc4632#section-3.1).
    20  
    21  The remaining arguments, indicated as `newbits` above, each specify the number
    22  of additional network prefix bits for one returned address range. The return
    23  value is therefore a list with one element per `newbits` argument, each
    24  a string containing an address range in CIDR notation.
    25  
    26  For more information on IP addressing concepts, see the documentation for the
    27  related function [`cidrsubnet`](/docs/job-specification/hcl2/functions/ipnet/cidrsubnet). `cidrsubnet` calculates
    28  a single subnet address within a prefix while allowing you to specify its
    29  subnet number, while `cidrsubnets` can calculate many at once, potentially of
    30  different sizes, and assigns subnet numbers automatically.
    31  
    32  When using this function to partition an address space as part of a network
    33  address plan, you must not change any of the existing arguments once network
    34  addresses have been assigned to real infrastructure, or else later address
    35  assignments will be invalidated. However, you _can_ append new arguments to
    36  existing calls safely, as long as there is sufficient address space available.
    37  
    38  This function accepts both IPv6 and IPv4 prefixes, and the result always uses
    39  the same addressing scheme as the given prefix.
    40  
    41  ## Examples
    42  
    43  ```shell-session
    44  > cidrsubnets("10.1.0.0/16", 4, 4, 8, 4)
    45  [
    46    "10.1.0.0/20",
    47    "10.1.16.0/20",
    48    "10.1.32.0/24",
    49    "10.1.48.0/20",
    50  ]
    51  
    52  > cidrsubnets("fd00:fd12:3456:7890::/56", 16, 16, 16, 32)
    53  [
    54    "fd00:fd12:3456:7800::/72",
    55    "fd00:fd12:3456:7800:100::/72",
    56    "fd00:fd12:3456:7800:200::/72",
    57    "fd00:fd12:3456:7800:300::/88",
    58  ]
    59  ```
    60  
    61  You can use nested `cidrsubnets` calls with
    62  [`for` expressions](/docs/job-specification/hcl2/expressions#for-expressions)
    63  to concisely allocate groups of network address blocks:
    64  
    65  ```shell-session
    66  > [for cidr_block in cidrsubnets("10.0.0.0/8", 8, 8, 8, 8) : cidrsubnets(cidr_block, 4, 4)]
    67  [
    68    [
    69      "10.0.0.0/20",
    70      "10.0.16.0/20",
    71    ],
    72    [
    73      "10.1.0.0/20",
    74      "10.1.16.0/20",
    75    ],
    76    [
    77      "10.2.0.0/20",
    78      "10.2.16.0/20",
    79    ],
    80    [
    81      "10.3.0.0/20",
    82      "10.3.16.0/20",
    83    ],
    84  ]
    85  ```
    86  
    87  ## Related Functions
    88  
    89  - [`cidrhost`](/docs/job-specification/hcl2/functions/ipnet/cidrhost) calculates the IP address for a single host
    90    within a given network address prefix.
    91  - [`cidrnetmask`](/docs/job-specification/hcl2/functions/ipnet/cidrnetmask) converts an IPv4 network prefix in CIDR
    92    notation into netmask notation.
    93  - [`cidrsubnet`](/docs/job-specification/hcl2/functions/ipnet/cidrsubnet) calculates a single subnet address, allowing
    94    you to specify its network number.