Create a vpc with all its accoutrements

mkvpc.py

#!/usr/bin/env python3
from __future__ import print_function

import boto3
import ipaddress
import sys
import time

ec2 = boto3.client('ec2')

def mkvpc(name, cidr, prefix_len, subnet_prefix_len, zones=['us-east-1e', 'us-east-1d', 'us-east-1c', 'us-east-1a']):
  network = ipaddress.ip_network(str(cidr) + '/' + str(prefix_len))
  cidrblock = str(network)
  n_subnets = len(zones)
  subnets = list(network.subnets(new_prefix=subnet_prefix_len))[:n_subnets]
  existing_vpcs = ec2.describe_vpcs()
  for vpc in existing_vpcs.get('Vpcs', []):
    if vpc.get('CidrBlock') == cidrblock:
      print('{} already exists'.format(cidrblock), file=sys.stderr)
      break
  else:
    vpc = ec2.create_vpc(CidrBlock=str(network), InstanceTenancy='default')['Vpc']
    is_available = False
    while not is_available:
      time.sleep(.1)
      for v in ec2.describe_vpcs().get('Vpcs', []):
        if v['CidrBlock'] == str(network) and v['State'] == 'available':
          is_available = True
          break
  vpcid = vpc['VpcId']
  while True:
    try:
      ec2.create_tags(Resources=[vpcid], Tags=[{'Key': 'Name', 'Value': name}])
      break
    except Exception as e:
      print(str(e), file=sys.stderr)
      time.sleep(.1)

  igw = ec2.create_internet_gateway()
  igwid = igw['InternetGateway']['InternetGatewayId']
  while True:
    try:
      ec2.attach_internet_gateway(InternetGatewayId=igwid, VpcId=vpcid)
      break
    except Exception as e:
      print(str(e), file=sys.stderr)
      time.sleep(.1)
  while True:
    try:
      ec2.create_tags(Resources=[igwid], Tags=[{'Key': 'Name', 'Value': name}])
      break
    except Exception as e:
      print(str(e), file=sys.stderr)
      time.sleep(.1)

  drt = ec2.describe_route_tables(Filters=[{'Name': 'vpc-id', 'Values': [vpcid]}])
  rts = drt['RouteTables']
  assert len(rts) == 1
  rt = rts[0]
  rtid = rt['RouteTableId']
  ec2.create_tags(Resources=[rtid], Tags=[{'Key': 'Name', 'Value': name}])
  ec2.create_route(RouteTableId=rtid, DestinationCidrBlock='0.0.0.0/0', GatewayId=igwid)

  odhoid = vpc['DhcpOptionsId']
  dho = ec2.create_dhcp_options(DhcpConfigurations=[
    {
      'Key': 'domain-name',
      'Values': ['net-10-20.example.com'],
    },
    {
      'Key': 'domain-name-servers',
      'Values': ['AmazonProvidedDNS'],
    },
  ])
  dhoid = dho['DhcpOptions']['DhcpOptionsId']
  while True:
    try:
      ec2.describe_dhcp_options(DhcpOptionsIds=[dhoid])
      break
    except Exception as e:
      print(str(e), file=sys.stderr)
      time.sleep(.1)
  ec2.create_tags(Resources=[dhoid], Tags=[{'Key': 'Name', 'Value': name}])
  ass = ec2.associate_dhcp_options(DhcpOptionsId=dhoid, VpcId=vpcid)
  ec2.delete_dhcp_options(DhcpOptionsId=odhoid)

  for i in range(n_subnets):
    cs = ec2.create_subnet(VpcId=vpcid, CidrBlock=str(subnets[i]), AvailabilityZone=zones[i])
    sn = cs['Subnet']
    snid = sn['SubnetId']
    while True:
      try:
        ec2.create_tags(Resources=[snid], Tags=[{'Key': 'Name', 'Value': name + '-' + zones[i]}])
        break
      except Exception as e:
        print(str(e), file=sys.stderr)
        time.sleep(.1)

mkvpc('prod', ipaddress.IPv4Address('10.20.0.0'), 16, 20)