Create an AWS VPC and Subnet using the AWS CLI and Bash

For those learning AWS/AWS CLI this is a quick document on how create an AWS VPC and Subnet using the AWS CLI (AWS Command Line Interface) from a Linux/Bash script.

The below bash script performs the following:

  1. adds a new VPC
  2. names the VPC
  3. adds dns support
  4. adds a dns hostname
  5. creates an internet gateway
  6. names the internet gateway
  7. creates the subnet
  8. names the subnet
  9. enables public ip on the subnet
  10. creates the security group for the subnet
  11. names the security group
  12. enables port 22 for ssh
  13. creates the route table
  14. names the route table
  15. adds route to the internet gateway
  16. adds the route table to the subnet

I am using the jq Command-line JSON processor to capture JSON output from each AWS CLI command. If using a RHEL/CentOS 7 jq is found in EPEL.

The private ip subnet will be created in the bash script and will be mapped to a public ip that is provided by AWS. After you build an AWS Linux instance with the vpc, subnet and security group you will be able to access the instance through:

ssh -i “yourPrivateKeyFile.pem”

Here is the create-aws-vpc bash script:

# create-aws-vpc
#variables used in script:
name="your VPC/network name"
vpcName="$name VPC"
subnetName="$name Subnet"
gatewayName="$name Gateway"
routeTableName="$name Route Table"
securityGroupName="$name Security Group"
echo "Creating VPC..."#create vpc with cidr block /16
aws_response=$(aws ec2 create-vpc \
--cidr-block "$vpcCidrBlock" \
--output json)
vpcId=$(echo -e "$aws_response" | /usr/bin/jq '.Vpc.VpcId' | tr -d '"')
#name the vpc
aws ec2 create-tags \
--resources "$vpcId" \
--tags Key=Name,Value="$vpcName"
#add dns support
modify_response=$(aws ec2 modify-vpc-attribute \
--vpc-id "$vpcId" \
--enable-dns-support "{\"Value\":true}")
#add dns hostnames
modify_response=$(aws ec2 modify-vpc-attribute \
--vpc-id "$vpcId" \
--enable-dns-hostnames "{\"Value\":true}")
#create internet gateway
gateway_response=$(aws ec2 create-internet-gateway \
--output json)
gatewayId=$(echo -e "$gateway_response" | /usr/bin/jq '.InternetGateway.InternetGatewayId' | tr -d '"')
#name the internet gateway
aws ec2 create-tags \
--resources "$gatewayId" \
--tags Key=Name,Value="$gatewayName"
#attach gateway to vpc
attach_response=$(aws ec2 attach-internet-gateway \
--internet-gateway-id "$gatewayId" \
--vpc-id "$vpcId")
#create subnet for vpc with /24 cidr block
subnet_response=$(aws ec2 create-subnet \
--cidr-block "$subNetCidrBlock" \
--availability-zone "$availabilityZone" \
--vpc-id "$vpcId" \
--output json)
subnetId=$(echo -e "$subnet_response" | /usr/bin/jq '.Subnet.SubnetId' | tr -d '"')
#name the subnet
aws ec2 create-tags \
--resources "$subnetId" \
--tags Key=Name,Value="$subnetName"
#enable public ip on subnet
modify_response=$(aws ec2 modify-subnet-attribute \
--subnet-id "$subnetId" \
#create security group
security_response=$(aws ec2 create-security-group \
--group-name "$securityGroupName" \
--description "Private: $securityGroupName" \
--vpc-id "$vpcId" --output json)
groupId=$(echo -e "$security_response" | /usr/bin/jq '.GroupId' | tr -d '"')
#name the security group
aws ec2 create-tags \
--resources "$groupId" \
--tags Key=Name,Value="$securityGroupName"
#enable port 22
security_response2=$(aws ec2 authorize-security-group-ingress \
--group-id "$groupId" \
--protocol tcp --port 22 \
--cidr "$port22CidrBlock")
#create route table for vpc
route_table_response=$(aws ec2 create-route-table \
--vpc-id "$vpcId" \
--output json)
routeTableId=$(echo -e "$route_table_response" | /usr/bin/jq '.RouteTable.RouteTableId' | tr -d '"')
#name the route table
aws ec2 create-tags \
--resources "$routeTableId" \
--tags Key=Name,Value="$routeTableName"
#add route for the internet gateway
route_response=$(aws ec2 create-route \
--route-table-id "$routeTableId" \
--destination-cidr-block "$destinationCidrBlock" \
--gateway-id "$gatewayId")
#add route to subnet
associate_response=$(aws ec2 associate-route-table \
--subnet-id "$subnetId" \
--route-table-id "$routeTableId")
echo " "
echo "VPC created:"
echo "Use subnet id $subnetId and security group id $groupId"
echo "To create your AWS instances"
# end of create-aws-vpc