Unix Bash/Shell script to create Custom VPC in AWS

This article provides you a unix shell script which creates following resources under your AWS account. You can download the script from the link "VPC Setup Script"

AWS Resources Created by the script

• VPC with CIDR prefix 10.0.0.0/24
• Public Subnet with CIDR prefix 10.0.0.0/25
• Private Subnets with CIDR prefix 10.0.0.128/25
• Internet Gateway 
• Routing Tables for public and private subnets
• NAT Gateway
• Elastic IP
• EC2 instance 1 of type t2.micro in private subnet
• EC2 instance 2 of type t2.micro in public subnet

Please ensure to delete these resources when you don't need them or else you will be charged by Amazon as per the pricing policy for these services.

Pre-requisites:

This program uses AWS command line interface. If you do not have it already, then install AWS CLI before running this script. You can download and install AWS CLI using the AWS CLI Installer Link. 

Linux Shell Script Code: 

• Copy the below code and put it in a text file. Save the text file with .sh extension.
• If you want your VPC in different CDR range, then modify the CIDR prefixes at line# 1,5 & 6.
• During the EC2 instance creation in last 2 lines, change the name of the private key file. This script uses the private key file name as "myec2key"

Contents of shell script vpc_setup.sh

export CIDR=10.0.0.0/24

aws ec2 create-vpc --cidr-block $CIDR > aws_output.txt

cat aws_output.txt

export vpcid=`egrep VpcId aws_output.txt | cut -d":" -f2 | sed 's/"//g' | sed 's/,//g' | cut -d" " -f2`

export CIDRPublic=10.0.0.0/25

export CIDRPrivate=10.0.0.128/25

aws ec2 create-subnet --vpc-id $vpcid --cidr-block $CIDRPublic > aws_output.txt

cat aws_output.txt

export pubsubnetid=`egrep SubnetId aws_output.txt | cut -d":" -f2 | sed 's/"//g' | sed 's/,//g' | cut -d" " -f2`

aws ec2 create-subnet --vpc-id $vpcid --cidr-block $CIDRPrivate > aws_output.txt

cat aws_output.txt

export privsubnetid=`egrep SubnetId aws_output.txt | cut -d":" -f2 | sed 's/"//g' | sed 's/,//g' | cut -d" " -f2`

aws ec2 create-internet-gateway > aws_output.txt

cat aws_output.txt

export IGW=`egrep InternetGatewayId aws_output.txt | cut -d":" -f2 | sed 's/"//g' | sed 's/,//g' | cut -d" " -f2`

aws ec2 attach-internet-gateway --vpc-id $vpcid --internet-gateway-id $IGW

aws ec2 create-route-table --vpc-id $vpcid > aws_output.txt

cat aws_output.txt

export RoutePublic=`egrep RouteTableId aws_output.txt | cut -d":" -f2 | sed 's/"//g' | sed 's/,//g' | cut -d" " -f2`

aws ec2 create-route-table --vpc-id $vpcid > aws_output.txt

cat aws_output.txt

export RoutePrivate=`egrep RouteTableId aws_output.txt | cut -d":" -f2 | sed 's/"//g' | sed 's/,//g' | cut -d" " -f2`

aws ec2 associate-route-table --subnet-id $pubsubnetid --route-table-id $RoutePublic

aws ec2 associate-route-table --subnet-id $privsubnetid --route-table-id $RoutePrivate

aws ec2 modify-subnet-attribute --subnet-id $privsubnetid --map-public-ip-on-launch

aws ec2 create-route --route-table-id $RoutePublic --destination-cidr-block 0.0.0.0/0 --gateway-id $IGW

aws ec2 allocate-address  > aws_output.txt

cat aws_output.txt

export EIP=`egrep AllocationId aws_output.txt | cut -d":" -f2 | sed 's/"//g' | sed 's/,//g' | cut -d" " -f2`

aws ec2 create-nat-gateway --subnet-id $privsubnetid --allocation-id $EIP > aws_output.txt

cat aws_output.txt

export NAT=`egrep NatGatewayId aws_output.txt | cut -d":" -f2 | sed 's/"//g' | sed 's/,//g' | cut -d" " -f2`

while true

do

aws ec2 describe-nat-gateways --nat-gateway-id $NAT > aws_output1.txt

export state=`egrep State aws_output1.txt | cut -d":" -f2 | sed 's/"//g' | sed 's/,//g' | cut -d" " -f2`

if [ "$state" != "pending" ]

then

break

fi

echo "waiting for NAT allocation sleeping for 20s"

sleep 20

done

aws ec2 create-route --route-table-id $RoutePrivate --destination-cidr-block 0.0.0.0/0 --gateway-id $NAT

aws ec2 run-instances --image-id ami-0810abbfb78d37cdf --count 1 --instance-type t2.micro --key-name myec2key --subnet-id $pubsubnetid >aws_output.txt

cat aws_output.txt

aws ec2 run-instances --image-id ami-0810abbfb78d37cdf --count 1 --instance-type t2.micro --key-name myec2key --subnet-id $privsubnetid >aws_output.txt

cat aws_output.txt