main.tf

resource "aws_vpc" "main" {
  cidr_block           = var.vpc_cidr_block
  enable_dns_support   = true
  enable_dns_hostnames = true
}

resource "aws_subnet" "public" {
  count                   = length(var.public_subnet_cidr_blocks)
  vpc_id                  = aws_vpc.main.id
  cidr_block              = var.public_subnet_cidr_blocks[count.index]
  map_public_ip_on_launch = true
  availability_zone       = var.availability_zones[count.index]
}

resource "aws_subnet" "private" {
  count             = length(var.private_subnet_cidr_blocks)
  vpc_id            = aws_vpc.main.id
  cidr_block        = var.private_subnet_cidr_blocks[count.index]
  availability_zone = var.availability_zones[count.index]
}

resource "aws_internet_gateway" "gw" {
  vpc_id = aws_vpc.main.id
}

resource "aws_nat_gateway" "nat" {
  count         = length(var.public_subnet_cidr_blocks)
  subnet_id     = element(aws_subnet.public[*].id, count.index)
  allocation_id = aws_eip.nat[count.index].id
}

resource "aws_eip" "nat" {
  count = length(var.public_subnet_cidr_blocks)
}

resource "aws_route_table" "public" {
  vpc_id = aws_vpc.main.id

  route {
    cidr_block = "0.0.0.0/0"
    gateway_id = aws_internet_gateway.gw.id
  }

  tags = {
    Name = "public"
  }
}

resource "aws_route_table_association" "public" {
  count          = length(var.public_subnet_cidr_blocks)
  subnet_id      = aws_subnet.public[count.index].id
  route_table_id = aws_route_table.public.id
}

resource "aws_route_table" "private" {
  count = length(var.private_subnet_cidr_blocks)

  vpc_id = aws_vpc.main.id

  route {
    cidr_block     = "0.0.0.0/0"
    nat_gateway_id = element(aws_nat_gateway.nat[*].id, count.index)
  }

  tags = {
    Name = "private"
  }
}

resource "aws_route_table_association" "private" {
  count          = length(var.private_subnet_cidr_blocks)
  subnet_id      = aws_subnet.private[count.index].id
  route_table_id = aws_route_table.private[count.index].id
}