Graph AWS Route Tables

route_tables.py

#!/usr/bin/env python
"""
./route_tables.py | dot -Tpng > routes.png
"""
import boto3

def get_tag(obj, key, default=''):
    for tag in obj['Tags']:
        if tag['Key'] == key:
            return tag['Value']
    return default

def main():
    ec2 = boto3.client('ec2')
    vpcs = ec2.describe_vpcs()['Vpcs']
    rtbls = ec2.describe_route_tables()['RouteTables']

    VPCs = {}
    tables = []
    lines = ["digraph VPC {"]
    for vpc in vpcs:
        VPCs[vpc['VpcId']] = {'vpc': vpc, 'rtb': []}
    for rtb in rtbls:
        VPCs[rtb['VpcId']]['rtb'].append(rtb)

    for vpc_id in VPCs:
        vpc = VPCs[vpc_id]
        v = vpc['vpc']
        rtbls = vpc['rtb']
        for r in rtbls:
            for rt in r['Routes']:
                if rt['State'] != 'active': continue
                if 'GatewayId' in rt:
                    dst = rt['GatewayId']
                elif 'VpcPeeringConnectionId' in rt:
                    dst = rt['VpcPeeringConnectionId']
                else:
                    dst = "|".join(rt.keys())


                if 'DestinationCidrBlock' in rt:
                    tgt = rt['DestinationCidrBlock']
                elif 'DestinationPrefixListId' in rt:
                    tgt = rt['DestinationPrefixListId']
                else:
                    tgt = "|".join(rt.keys())
                lines.append("""    "{}" -> "{}" """.format(v['CidrBlock'], tgt))
    lines.append("}")
    print("\n".join(lines))

if __name__ == "__main__":
    vpcs = main()