Katbin

# Variable Values That Am using
AWS_REGION          = "us-east-2"
VPC_NAME            = "SomeVPC"
VPC_CIDR            = "10.0.0.0/16"
PUBLIC_SUBNET_CIDR  = ["10.0.1.0/24", "10.0.2.0/24","10.0.3.0/24"]
PRIVATE_SUBNET_CIDR = ["10.0.4.0/24", "10.0.5.0/24", "10.0.6.0/24"]
AVAILABILITY_ZONE   = ["us-east-2a", "us-east-2b", "us-east-2c"]
IPV4_CIDR_BLOCK     = "0.0.0.0/0"
IPV6_CIDR_BLOCK     = "::/0"

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# Create a VPC 
resource "aws_vpc" "VPC" {
  cidr_block                       = var.VPC_CIDR
  enable_dns_support               = true
  enable_dns_hostnames             = true
  assign_generated_ipv6_cidr_block = true
  tags = {
    Name      = var.VPC_NAME
    CreatedBy = "Terraform"
  }
}

# Create Public Subnets
resource "aws_subnet" "public_subnets" {
  count           = length(var.PUBLIC_SUBNET_CIDR)
  vpc_id          = aws_vpc.VPC.id
  cidr_block      = element(var.PUBLIC_SUBNET_CIDR, count.index)
  ipv6_cidr_block = cidrsubnet(aws_vpc.VPC.ipv6_cidr_block, 8, count.index)

  availability_zone               = element(var.AVAILABILITY_ZONE, count.index)
  map_public_ip_on_launch         = true
  assign_ipv6_address_on_creation = true

  tags = {
    Name      = "Public Subnet ${count.index + 1}"
    CreatedBy = "Terraform"

  }
}

# Create Private Subnets
resource "aws_subnet" "private_subnets" {
  count             = length(var.PRIVATE_SUBNET_CIDR)
  vpc_id            = aws_vpc.VPC.id
  cidr_block        = element(var.PRIVATE_SUBNET_CIDR, count.index)
  availability_zone = element(var.AVAILABILITY_ZONE, count.index)

  tags = {
    Name      = "Private Subnet ${count.index + 1}"
    CreatedBy = "Terraform"
  }
}

# Create Internet Gateway
resource "aws_internet_gateway" "gw" {
  vpc_id = aws_vpc.VPC.id

  tags = {
    Name      = "Internet Gateway"
    CreatedBy = "Terraform"
  }
}

# Create Routing Table for Public Subnets
resource "aws_route_table" "public_routing_table" {
  vpc_id = aws_vpc.VPC.id
  route {
    cidr_block = var.IPV4_CIDR_BLOCK
    gateway_id = aws_internet_gateway.gw.id
  }
  route {
    ipv6_cidr_block = var.IPV6_CIDR_BLOCK
    gateway_id      = aws_internet_gateway.gw.id
  }
  tags = {
    Name      = "Public Route Table"
    CreatedBy = "Terraform"

  }
}

# Create Routing Table for Private Subnets
resource "aws_route_table" "private_routing_table" {
  count  = length(var.PRIVATE_SUBNET_CIDR)
  vpc_id = aws_vpc.VPC.id
  route {
    cidr_block = var.IPV4_CIDR_BLOCK
    gateway_id = aws_internet_gateway.gw.id
  }
  route {
    ipv6_cidr_block = var.IPV6_CIDR_BLOCK
    gateway_id      = aws_internet_gateway.gw.id
  }
  tags = {
    Name      = "Private Route Table"
    CreatedBy = "Terraform"

  }
}

# Associate Routing Table for Public Subnets
resource "aws_route_table_association" "public_subnet_asso" {
  count          = length(var.PUBLIC_SUBNET_CIDR)
  subnet_id      = element(aws_subnet.public_subnets[*].id, count.index)
  route_table_id = aws_route_table.public_routing_table.id
}

# Associate each subnet with the corresponding routing table
resource "aws_route_table_association" "private_subnet_asso" {
  count          = length(var.PRIVATE_SUBNET_CIDR)
  subnet_id      = element(aws_subnet.private_subnets[*].id, count.index)
  route_table_id = element(aws_route_table.private_routing_table.*.id, count.index)
}

# Create a Subnet Group for RDS
resource "aws_db_subnet_group" "subnet_group" {
  name        = "db_subnet"
  description = "Subnet group for RDS instance"
  subnet_ids  = concat(aws_subnet.public_subnets.*.id, aws_subnet.private_subnets.*.id)
  tags = {
    Name      = "DB Subnet"
    CreatedBy = "Terraform"
  }
}