Deploying into an existing AWS VPC

Tarmak has experimental support for deploying clusters into an existing AWS VPC.

To enable this, you will need to note down the IDs for the VPC and subnets you want to deploy to.

For example, if we have the following infrastructure (notation in terraform):

provider "aws" {}

data "aws_availability_zones" "available" {}

resource "aws_vpc" "main" {
  cidr_block = "10.0.0.0/16"
  enable_dns_support   = true
  enable_dns_hostnames = true

  tags {
        Name = "test_vpc"
  }
}

resource "aws_eip" "nat" {
  vpc = true
}

resource "aws_subnet" "public" {
  count             = "${length(data.aws_availability_zones.available.names)}"
  vpc_id            = "${aws_vpc.main.id}"
  cidr_block        = "${cidrsubnet(cidrsubnet(aws_vpc.main.cidr_block, 3, 0), 3, count.index)}"
  availability_zone = "${data.aws_availability_zones.available.names[count.index]}"

  tags {
        Name = "public_${data.aws_availability_zones.available.names[count.index]}"
  }
}

resource "aws_subnet" "private" {
  count             = "${length(data.aws_availability_zones.available.names)}"
  vpc_id            = "${aws_vpc.main.id}"
  cidr_block        = "${cidrsubnet(aws_vpc.main.cidr_block, 3, count.index + 1)}"
  availability_zone = "${data.aws_availability_zones.available.names[count.index]}"

  tags {
        Name = "private_${data.aws_availability_zones.available.names[count.index]}"
  }
}

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

resource "aws_nat_gateway" "main" {
  count         = "${length(aws_subnet.public)}"
  depends_on    = ["aws_internet_gateway.main"]
  allocation_id = "${aws_eip.nat.id}"
  subnet_id     = "${aws_subnet.public.*.id[count.index]}"
}

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

resource "aws_route" "public" {
  route_table_id         = "${aws_route_table.public.id}"
  destination_cidr_block = "0.0.0.0/0"
  gateway_id             = "${aws_internet_gateway.main.id}"
}

resource "aws_route_table" "private" {
  vpc_id = "${aws_vpc.main.id}"
}

resource "aws_route" "private" {
  route_table_id         = "${aws_route_table.private.id}"
  destination_cidr_block = "0.0.0.0/0"
  nat_gateway_id         = "${aws_nat_gateway.main.id}"
}

resource "aws_route_table_association" "public" {
  count          = "${length(data.aws_availability_zones.available.names)}"
  subnet_id      = "${aws_subnet.public.*.id[count.index]}"
  route_table_id = "${aws_route_table.public.id}"
}

resource "aws_route_table_association" "private" {
  count          = "${length(data.aws_availability_zones.available.names)}"
  subnet_id      = "${aws_subnet.private.*.id[count.index]}"
  route_table_id = "${aws_route_table.private.id}"
}

Run tarmak init as normal. Before running the apply stage, add the following annotations to your clusters network configuration (located in ~/.tarmak/tarmak.yaml):

network:
  cidr: 10.99.0.0/16
  metadata:
        creationTimestamp: null
        annotations:
          tarmak.io/existing-vpc-id: vpc-xxxxxxxx
          tarmak.io/existing-public-subnet-ids: subnet-xxxxxxxx,subnet-xxxxxxxx,subnet-xxxxxxxx
          tarmak.io/existing-private-subnet-ids: subnet-xxxxxxxx,subnet-xxxxxxxx,subnet-xxxxxxxx

Now you can run tarmak cluster apply and continue as normal.