subnetted

subnetme.py

import sys
import itertools

from netaddr import IPNetwork
from netaddr import cidr_merge

AWS_RESERVED_IPS = 5

ALLOCATIONS = {
    "small": {
        "base_bits": 26,
        "zone_bits": 28,
    },
    "medium": {
        "base_bits": 24,
        "zone_bits": 26,
    },
    "large": {
        "base_bits": 22,
        "zone_bits": 24,
    },
}

BLOCKS = dict([
    ("small", 1),
    ("medium", 2),
    ("large", 1),
])

base = "10.173.0.0/16"
split = 18

network = IPNetwork(base)
subnets = list(network.subnet(split))

zones = itertools.cycle(['us-east-1c', 'us-east-1d', 'us-east-1e', 'reserved'])

stats = {}

sys.stdout.write("class,type,availability_zone,cidr,usable_ips,allocated_bool,allocation_purpose\n")
for block, size in BLOCKS.items():
    subnet_allocation = []
    for _ in range(size):
        subnet_allocation.append(subnets.pop())
    subnet_allocation = cidr_merge(subnet_allocation)[0]
    allocation_subnets = subnet_allocation.subnet(ALLOCATIONS[block]['base_bits'])
    for subnet in allocation_subnets:
        stats[block] = stats.get(block, 0) + 1
        sys.stdout.write("%s,parent,,%s,%s,,\n" % (block, subnet, subnet.size - 4 * AWS_RESERVED_IPS))
        for subsubnet in subnet.subnet(ALLOCATIONS[block]['zone_bits']):
            sys.stdout.write(",child,%s,%s,%s,,\n" % (zones.next(), subsubnet, subsubnet.size - AWS_RESERVED_IPS))

sys.stderr.write(str(stats) + "\n")

zoutput.csv