3-tier -> Public & Private RTs

main.tf

# Private route table
resource "aws_route_table" "private-rt" {
  vpc_id = aws_vpc.main-vpc.id

  tags = {
    Name = "${var.vpc_name}-private-rt"
  }
}

# Private route table routes
resource "aws_route" "private-route" {
  route_table_id = aws_route_table.private-rt.id
  destination_cidr_block = "0.0.0.0/0"
  nat_gateway_id = aws_nat_gateway.nat.id
}

# Associate private subnet 1 (app tier) with private route table
resource "aws_route_table_association" "app-privatesubnet1-association" {
  subnet_id = aws_subnet.app-privatesubnet1.id
  route_table_id = aws_route_table.private-rt.id
}

# Associate private subnet 2 (app tier) with private route table
resource "aws_route_table_association" "app-privatesubnet2-association" {
  subnet_id = aws_subnet.app-privatesubnet2.id
  route_table_id = aws_route_table.private-rt.id
}

# Associate private subnet 1 (db tier) with private route table
resource "aws_route_table_association" "db-privatesubnet1-association" {
  subnet_id = aws_subnet.db-privatesubnet1.id
  route_table_id = aws_route_table.private-rt.id
}

# Associate private subnet 2 (db tier) with private route table
resource "aws_route_table_association" "db-privatesubnet2-association" {
  subnet_id = aws_subnet.db-privatesubnet2.id
  route_table_id = aws_route_table.private-rt.id
}

# Public route table routes
resource "aws_route_table" "main-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 = "${var.vpc_name}-main-rt"
  }
}

# Associate Web tier public subnet 1 with main route table
resource "aws_route_table_association" "publicsubnet1-association" {
  subnet_id = aws_subnet.publicsubnet1.id
  route_table_id = aws_route_table.main-rt.id
}

# Associate Web tier public subnet 2 with main route table
resource "aws_route_table_association" "publicsubnet2-association" {
  subnet_id = aws_subnet.publicsubnet2.id
  route_table_id = aws_route_table.main-rt.id
}