My Journey to the cloud…

import csv
import sys
import os
import boto3
import logging
import argparse
import traceback
from botocore.exceptions import ClientError
from datetime import datetime, timedelta, timezone

date_time_now = datetime.now().strftime('%Y/%m/%d  %H:%M:%S')


DEFAULT_REGION = "us-east-1"
vpcid = tgwFlag = vpcCIDR = ""



def ec2_client(region):
    """
    Connects to EC2, returns a connection object
    """
    try:
        conn = boto3.client('ec2', region_name=region)

    except Exception as e:
        sys.stderr.write(
            'Could not connect to region: %s. Exception: %s\n' % (region, e))
        conn = None

    return conn


def parse_commandline_arguments():
    global REGION
    global ACCOUNT_ID
    global report_filename

    parser = argparse.ArgumentParser(formatter_class=argparse.ArgumentDefaultsHelpFormatter,
                                     description='Create a CSV Report for Subnet Info.')
    parser.add_argument("-id", "--accountID", dest="account_id", type=str,required=True,
                        help="The AWS Account Name for which the Subnet info is neeeded")
    parser.add_argument("-r", "--region", dest="region", type=str,
                        default=DEFAULT_REGION, help="Specify the global region to pull the report")
    parser.add_argument("-f", "--report", dest="reportname", type=str,
                        help="Specify the report file Name with path")
    args = parser.parse_args()

    ACCOUNT_ID= args.account_id
    REGION = args.region
    report_filename = args.reportname


def getvpcinfo(client,awsRegion):
    global vpcid
    global vpcCIDR
    vpcCIDR = vpcid = ""
    # if you want to retrict your list ONLY to any specific VPC Name
    #filtervpc = [{'Name':'tag:Name', 'Values':['vpc-main']}]
    try:
        #response = client.describe_vpcs(Filters=filtervpc)
        response = client.describe_vpcs()
        for vpc in response["Vpcs"]:
            vpcid = vpc["VpcId"]
            vpcCIDR = vpc["CidrBlock"]
            #print("VPC ID and VPC CIDR is - {} , {}" .format(vpcid,vpcCIDR))
            getsubnetinfo(vpcid,vpcCIDR,client,awsRegion)
        #return vpcid,vpcCIDR
        return None
    except Exception as e:
        logging.error(e)


def get_transitgateway_info(client):
    global tgwFlag
    try:
        response = client.describe_transit_gateways()
        if len(response['TransitGateways']) > 0:
            for tgw in response['TransitGateways']:
                tgwID = tgw['TransitGatewayId']
                tgwFlag = "Y"
        else:
            tgwFlag = "N"
        return tgwFlag
    except Exception as e:
        logging.error(e)


def getsubnetinfo(vpcid,vpc_cidr,client,region):
    OwnerId = subnetID = AvailabilityZone = CidrBlock = VpcId = vpcCIDR = ""
    filtersubnet = [{'Name':'vpc-id', 'Values':[vpcid]}]
    vpcCIDR = vpc_cidr
    try:
        tgwFlag = get_transitgateway_info(client)
        responsesubnet = client.describe_subnets(Filters=filtersubnet)
        datalist = responsesubnet["Subnets"]
        for i in range(len(datalist)):
            for key in datalist[i]:
                if key == 'SubnetId':
                    subnetID = datalist[i][key]
                if key == 'AvailabilityZone':
                    AvailabilityZone = datalist[i][key]
                if key == 'CidrBlock':
                    CidrBlock = datalist[i][key]
                if key == 'VpcId':
                    VpcId = datalist[i][key]
                if key == 'OwnerId':
                    OwnerId = datalist[i][key]
            print_string = OwnerId + "," + region + "," + subnetID + "," + AvailabilityZone + "," + CidrBlock + "," + VpcId + "," +  vpcCIDR + "," + tgwFlag + "," + date_time_now
            print(print_string)
            file.write(print_string + "\n")
    except Exception as e:
        logging.error(e)
                
    

if __name__ == '__main__':
    try:
        parse_commandline_arguments()
        client = ec2_client(REGION)
        if not os.path.isfile(report_filename):
            file = open(report_filename, 'w+')
            print_string_hdr = "AccountID,Region,SubnetID,AvailabilityZone,CidrBlock,VpcId,VpcCIDR,TGW_Flag,Reporting_Date_Time\n"
            file.write(print_string_hdr)
        else:
            file = open(report_filename, 'a')
        getvpcinfo(client,REGION)
    except Exception as error:
        print(str(error))