Terraform is a powerful tool for automating infrastructure as code (IaC), making it easier to manage and deploy cloud resources. In this post, we'll be going through creating a Virtual Private Cloud (VPC) with one public and one private subnet in AWS.

resource "aws_vpc" "main_vpc" {
  cidr_block = "10.0.0.0/16"
  tags = {
    Name = "main_vpc"
  }
}

resource "aws_subnet" "public_subnet" {
  vpc_id            = aws_vpc.main_vpc.id
  cidr_block        = "10.0.1.0/24"
  map_public_ip_on_launch = true
  availability_zone = "us-east-1a"
  tags = {
    Name = "public_subnet"
  }
}

resource "aws_subnet" "private_subnet" {
  vpc_id            = aws_vpc.main_vpc.id
  cidr_block        = "10.0.2.0/24"
  availability_zone = "us-east-1a"
  tags = {
    Name = "private_subnet"
  }
}

resource "aws_internet_gateway" "igw" {
  vpc_id = aws_vpc.main_vpc.id
  tags = {
    Name = "main_igw"
  }
}

resource "aws_route_table" "public_rt" {
  vpc_id = aws_vpc.main_vpc.id
  route {
    cidr_block = "0.0.0.0/0"
    gateway_id = aws_internet_gateway.igw.id
  }
  tags = {
    Name = "public_rt"
  }
}

resource "aws_route_table_association" "public_subnet_assoc" {
  subnet_id      = aws_subnet.public_subnet.id
  route_table_id = aws_route_table.public_rt.id
}

resource "aws_nat_gateway" "nat" {
  allocation_id = aws_eip.nat_eip.id
  subnet_id     = aws_subnet.public_subnet.id
  tags = {
    Name = "main_nat"
  }
}

resource "aws_eip" "nat_eip" {
  vpc = true
  depends_on = [aws_internet_gateway.igw]
}

resource "aws_route_table" "private_rt" {
  vpc_id = aws_vpc.main_vpc.id
  route {
    cidr_block     = "0.0.0.0/0"
    nat_gateway_id = aws_nat_gateway.nat.id
  }
  tags = {
    Name = "private_rt"
  }
}

resource "aws_route_table_association" "private_subnet_assoc" {
  subnet_id      = aws_subnet.private_subnet.id
  route_table_id = aws_route_table.private_rt.id
}