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.”)