How can I use the AWS subnets for the separation of public and private Resources in a multi-tier architecture?

 In the context of AWS, here is how you can use the AWS subnets to achieve the separation between public and private Resources in a multi-tier architecture:-

Using subnets for public and private Resources

Public subnet

You can create a public subnet for the web-based server tier. You should associate this subnet with a particular route table which has a route to an internet gateway which would help in allowing outbound Internet access for the web server.

Private subnets

You can create a private subnet for the database tier. Do not try to associate these subnets with a route to the IGW, ensuring that it should remain isolated from Direct internet access.

Here is an example given of how you can create a subnet and associates the resource by using the AWS CLI:-

# Create VPC

Aws ec2 create-vpc –cidr-block 10.0.0.0/16

# Create public subnet

Aws ec2 create-subnet –vpc-id your_vpc_id –cidr-block 10.0.1.0/24 –availability-zone us-east-1a

# Create private subnet

Aws ec2 create-subnet –vpc-id your_vpc_id –cidr-block 10.0.2.0/24 –availability-zone us-east-1b

# Create Internet Gateway

Aws ec2 create-internet-gateway

# Attach Internet Gateway to VPC

Aws ec2 attach-internet-gateway –vpc-id your_vpc_id –internet-gateway-id your_igw_id

# Create Route Table for public subnet

Aws ec2 create-route-table –vpc-id your_vpc_id

Aws ec2 create-route –route-table-id your_route_table_id –destination-cidr-block 0.0.0.0/0 –gateway-id your_Igw_id

# Associate Route Table with public subnet

Aws ec2 associate-route-table –subnet-id your_public_subnet_id –route-table-id your_route_table_id

Here is the example given in python programming language:-

Import boto3

# Initialize Boto3 client for EC2

Ec2_client = boto3.client(‘ec2’)

# Create VPC

Vpc_response = ec2_client.create_vpc(CidrBlock=’10.0.0.0/16’)

Vpc_id = vpc_response[‘Vpc’][‘VpcId’]

# Create public subnet

Public_subnet_response = ec2_client.create_subnet(

    VpcId=vpc_id,

    CidrBlock=’10.0.1.0/24’,

    AvailabilityZone=’us-east-1a’

)

Public_subnet_id = public_subnet_response[‘Subnet’][‘SubnetId’]

# Create private subnet

Private_subnet_response = ec2_client.create_subnet(

    VpcId=vpc_id,

    CidrBlock=’10.0.2.0/24’,

    AvailabilityZone=’us-east-1b’

)

Private_subnet_id = private_subnet_response[‘Subnet’][‘SubnetId’]

# Create Internet Gateway

Igw_response = ec2_client.create_internet_gateway()

Igw_id = igw_response[‘InternetGateway’][‘InternetGatewayId’]

# Attach Internet Gateway to VPC

Ec2_client.attach_internet_gateway(VpcId=vpc_id, InternetGatewayId=igw_id)

# Create Route Table for public subnet

Route_table_response = ec2_client.create_route_table(VpcId=vpc_id)

Route_table_id = route_table_response[‘RouteTable’][‘RouteTableId’]

# Create route to Internet Gateway

Ec2_client.create_route(

    RouteTableId=route_table_id,

    DestinationCidrBlock=’0.0.0.0/0’,

    GatewayId=igw_id

)

# Associate Route Table with public subnet

Ec2_client.associate_route_table(

    SubnetId=public_subnet_id,

    RouteTableId=route_table_id

)

Print(“Subnets and associated resources created successfully.”)