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tschuy / cidrblocks

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cidrblocks

Generate subnets within Availability Zones from a CIDR.

CLI Usage

Only the --cidr flag is necessary. By default, it splits into four availability zones and outputs a table:

(cidrblocks)(master) → ./cidrblocks --cidr=10.0.0.0/20
VPC Range - 10.0.0.0/20

AZ a (10.0.0.0/22):
    10.0.0.0/23 (Private - 512 addresses)
    10.0.2.0/24 (Public - 256 addresses)
    10.0.3.0/25 (Protected - 128 addresses)
    10.0.3.128/25 (Extra - 128 addresses)

AZ b (10.0.4.0/22):
    10.0.4.0/23 (Private - 512 addresses)
    10.0.6.0/24 (Public - 256 addresses)
    10.0.7.0/25 (Protected - 128 addresses)
    10.0.7.128/25 (Extra - 128 addresses)

AZ c (10.0.8.0/22):
    10.0.8.0/23 (Private - 512 addresses)
    10.0.10.0/24 (Public - 256 addresses)
    10.0.11.0/25 (Protected - 128 addresses)
    10.0.11.128/25 (Extra - 128 addresses)

AZ d (10.0.12.0/22):
    10.0.12.0/23 (Private - 512 addresses)
    10.0.14.0/24 (Public - 256 addresses)
    10.0.15.0/25 (Protected - 128 addresses)
    10.0.15.128/25 (Extra - 128 addresses)

The number of availability zones can be specified:

(cidrblocks)(master) → ./cidrblocks --cidr=10.0.0.0/20 --azs=3
VPC Range - 10.0.0.0/20

AZ a (10.0.0.0/22):
    10.0.0.0/23 (Private - 512 addresses)
    10.0.2.0/24 (Public - 256 addresses)
    10.0.3.0/25 (Protected - 128 addresses)
    10.0.3.128/25 (Extra - 128 addresses)

AZ b (10.0.4.0/22):
    10.0.4.0/23 (Private - 512 addresses)
    10.0.6.0/24 (Public - 256 addresses)
    10.0.7.0/25 (Protected - 128 addresses)
    10.0.7.128/25 (Extra - 128 addresses)

AZ c (10.0.8.0/22):
    10.0.8.0/23 (Private - 512 addresses)
    10.0.10.0/24 (Public - 256 addresses)
    10.0.11.0/25 (Protected - 128 addresses)
    10.0.11.128/25 (Extra - 128 addresses)

Unused blocks:
    10.0.12.0/22

It can also output in four formats:

(cidrblocks)(master) → ./cidrblocks --cidr=10.0.0.0/20 --format=cloudformation
{
    "AWSTemplateFormatVersion" : "2010-09-09",
    "Resources" : {
...

Web Service

Alternatively, cidrblocks can be run as a web service:

(cidrblocks)(master) → ./cidrblocks serve --port=8087

→ http://localhost:8087/?format=table&cidr=10.0.0.0/8
→ http://localhost:8087/?format=cloudformation&cidr=10.0.0.0/8&azs=2

Library

cidrblocks can also be used as a library within another application with the cidrblocks/subnet subpackage.