typhoon/docs/cl/digital-ocean.md

# Digital Ocean

In this tutorial, we'll create a Kubernetes v1.18.0 cluster on DigitalOcean with CoreOS Container Linux or Flatcar Linux.

We'll declare a Kubernetes cluster using the Typhoon Terraform module. Then apply the changes to create controller droplets, worker droplets, DNS records, tags, and TLS assets.

Controller hosts are provisioned to run an `etcd-member` peer and a `kubelet` service. Worker hosts run a `kubelet` service. Controller nodes run `kube-apiserver`, `kube-scheduler`, `kube-controller-manager`, and `coredns`, while `kube-proxy` and `calico` (or `flannel`) run on every node. A generated `kubeconfig` provides `kubectl` access to the cluster.

## Requirements

* Digital Ocean Account and Token
* Digital Ocean Domain (registered Domain Name or delegated subdomain)
* Terraform v0.12.6+ and [terraform-provider-ct](https://github.com/poseidon/terraform-provider-ct) installed locally

## Terraform Setup

Install [Terraform](https://www.terraform.io/downloads.html) v0.12.6+ on your system.

```sh
$ terraform version
Terraform v0.12.21
```

Add the [terraform-provider-ct](https://github.com/poseidon/terraform-provider-ct) plugin binary for your system to `~/.terraform.d/plugins/`, noting the final name.

```sh
wget https://github.com/poseidon/terraform-provider-ct/releases/download/v0.5.0/terraform-provider-ct-v0.5.0-linux-amd64.tar.gz
tar xzf terraform-provider-ct-v0.5.0-linux-amd64.tar.gz
mv terraform-provider-ct-v0.5.0-linux-amd64/terraform-provider-ct ~/.terraform.d/plugins/terraform-provider-ct_v0.5.0
```

Read [concepts](/architecture/concepts/) to learn about Terraform, modules, and organizing resources. Change to your infrastructure repository (e.g. `infra`).

```
cd infra/clusters
```

## Provider

Login to [DigitalOcean](https://cloud.digitalocean.com) or create an [account](https://cloud.digitalocean.com/registrations/new), if you don't have one.

Generate a Personal Access Token with read/write scope from the [API tab](https://cloud.digitalocean.com/settings/api/tokens). Write the token to a file that can be referenced in configs.

```sh
mkdir -p ~/.config/digital-ocean
echo "TOKEN" > ~/.config/digital-ocean/token
```

Configure the DigitalOcean provider to use your token in a `providers.tf` file.

```tf
provider "digitalocean" {
  version = "1.14.0"
  token = "${chomp(file("~/.config/digital-ocean/token"))}"
}

provider "ct" {
  version = "0.5.0"
}
```

## Cluster

Define a Kubernetes cluster using the module `digital-ocean/container-linux/kubernetes`.

```tf
module "nemo" {
  source = "git::https://github.com/poseidon/typhoon//digital-ocean/container-linux/kubernetes?ref=v1.18.0"

  # Digital Ocean
  cluster_name = "nemo"
  region       = "nyc3"
  dns_zone     = "digital-ocean.example.com"
  os_image     = "coreos-stable"

  # configuration
  ssh_fingerprints = ["d7:9d:79:ae:56:32:73:79:95:88:e3:a2:ab:5d:45:e7"]

  # optional
  worker_count = 2
}
```

Reference the [variables docs](#variables) or the [variables.tf](https://github.com/poseidon/typhoon/blob/master/digital-ocean/container-linux/kubernetes/variables.tf) source.

### Flatcar Linux Only

!!! warning
    Typhoon for Flatcar Linux on DigitalOcean is alpha. Also IPv6 is unsupported with DigitalOcean custom images.

Flatcar Linux publishes DigitalOcean images, but does not upload them. DigitalOcean allows [custom boot images](https://blog.digitalocean.com/custom-images/) by file or URL.

[Download](https://www.flatcar-linux.org/releases/) the Flatcar Linux DigitalOcean bin image (or copy the URL) and [upload](https://cloud.digitalocean.com/images/custom_images) it as a custom image. Rename the image with the channel and version to refer to these images over time.

```tf
module "nemo" {
  ...
  os_image = data.digitalocean_image.flatcar-stable.id
}

data "digitalocean_image" "flatcar-stable" {
  name = "flatcar-stable-2303.4.0.bin.bz2"
}
```

Set the [os_image](#variables) to the custom image id.

## ssh-agent

Initial bootstrapping requires `bootstrap.service` be started on one controller node. Terraform uses `ssh-agent` to automate this step. Add your SSH private key to `ssh-agent`.

```sh
ssh-add ~/.ssh/id_rsa
ssh-add -L
```

## Apply

Initialize the config directory if this is the first use with Terraform.

```sh
terraform init
```

Plan the resources to be created.

```sh
$ terraform plan
Plan: 54 to add, 0 to change, 0 to destroy.
```

Apply the changes to create the cluster.

```sh
$ terraform apply
module.nemo.null_resource.bootstrap: Still creating... (30s elapsed)
module.nemo.null_resource.bootstrap: Provisioning with 'remote-exec'...
...
module.nemo.null_resource.bootstrap: Still creating... (6m20s elapsed)
module.nemo.null_resource.bootstrap: Creation complete (ID: 7599298447329218468)

Apply complete! Resources: 42 added, 0 changed, 0 destroyed.
```

In 3-6 minutes, the Kubernetes cluster will be ready.

## Verify

[Install kubectl](https://kubernetes.io/docs/tasks/tools/install-kubectl/) on your system. Obtain the generated cluster `kubeconfig` from module outputs (e.g. write to a local file).

```
resource "local_file" "kubeconfig-nemo" {
  content  = module.nemo.kubeconfig-admin
  filename = "/home/user/.kube/configs/nemo-config"
}
```

List nodes in the cluster.

```
$ export KUBECONFIG=/home/user/.kube/configs/nemo-config
$ kubectl get nodes
NAME               STATUS  ROLES   AGE  VERSION
10.132.110.130     Ready   <none>  10m  v1.18.0
10.132.115.81      Ready   <none>  10m  v1.18.0
10.132.124.107     Ready   <none>  10m  v1.18.0
```

List the pods.

```
NAMESPACE     NAME                                       READY     STATUS    RESTARTS   AGE
kube-system   coredns-1187388186-ld1j7                   1/1       Running   0          11m
kube-system   coredns-1187388186-rdhf7                   1/1       Running   0          11m
kube-system   calico-node-1m5bf                          2/2       Running   0          11m
kube-system   calico-node-7jmr1                          2/2       Running   0          11m
kube-system   calico-node-bknc8                          2/2       Running   0          11m
kube-system   kube-apiserver-ip-10.132.115.81            1/1       Running   0          11m
kube-system   kube-controller-manager-ip-10.132.115.81   1/1       Running   0          11m
kube-system   kube-proxy-6kxjf                           1/1       Running   0          11m
kube-system   kube-proxy-fh3td                           1/1       Running   0          11m
kube-system   kube-proxy-k35rc                           1/1       Running   0          11m
kube-system   kube-scheduler-ip-10.132.115.81            1/1       Running   0          11m
```

## Going Further

Learn about [maintenance](/topics/maintenance/) and [addons](/addons/overview/).

## Variables

Check the [variables.tf](https://github.com/poseidon/typhoon/blob/master/digital-ocean/container-linux/kubernetes/variables.tf) source.

### Required

| Name | Description | Example |
|:-----|:------------|:--------|
| cluster_name | Unique cluster name (prepended to dns_zone) | "nemo" |
| region | Digital Ocean region | "nyc1", "sfo2", "fra1", tor1" |
| dns_zone | Digital Ocean domain (i.e. DNS zone) | "do.example.com" |
| ssh_fingerprints | SSH public key fingerprints | ["d7:9d..."] |

#### DNS Zone

Clusters create DNS A records `${cluster_name}.${dns_zone}` to resolve to controller droplets (round robin). This FQDN is used by workers and `kubectl` to access the apiserver(s). In this example, the cluster's apiserver would be accessible at `nemo.do.example.com`.

You'll need a registered domain name or delegated subdomain in Digital Ocean Domains (i.e. DNS zones). You can set this up once and create many clusters with unique names.

```tf
# Declare a DigitalOcean record to also create a zone file
resource "digitalocean_domain" "zone-for-clusters" {
  name       = "do.example.com"
  ip_address = "8.8.8.8"
}
```

!!! tip ""
    If you have an existing domain name with a zone file elsewhere, just delegate a subdomain that can be managed on DigitalOcean (e.g. do.mydomain.com) and [update nameservers](https://www.digitalocean.com/community/tutorials/how-to-set-up-a-host-name-with-digitalocean).

#### SSH Fingerprints

DigitalOcean droplets are created with your SSH public key "fingerprint" (i.e. MD5 hash) to allow access. If your SSH public key is at `~/.ssh/id_rsa`, find the fingerprint with,

```bash
ssh-keygen -E md5 -lf ~/.ssh/id_rsa.pub | awk '{print $2}'
MD5:d7:9d:79:ae:56:32:73:79:95:88:e3:a2:ab:5d:45:e7
```

If you use `ssh-agent` (e.g. Yubikey for SSH), find the fingerprint with,

```
ssh-add -l -E md5
2048 MD5:d7:9d:79:ae:56:32:73:79:95:88:e3:a2:ab:5d:45:e7 cardno:000603633110 (RSA)
```

Digital Ocean requires the SSH public key be uploaded to your account, so you may also find the fingerprint under Settings -> Security. Finally, if you don't have an SSH key, [create one now](https://help.github.com/articles/generating-a-new-ssh-key-and-adding-it-to-the-ssh-agent/).

### Optional

| Name | Description | Default | Example |
|:-----|:------------|:--------|:--------|
| controller_count | Number of controllers (i.e. masters) | 1 | 1 |
| worker_count | Number of workers | 1 | 3 |
| controller_type | Droplet type for controllers | "s-2vcpu-2gb" | s-2vcpu-2gb, s-2vcpu-4gb, s-4vcpu-8gb, ... |
| worker_type | Droplet type for workers | "s-1vcpu-2gb" | s-1vcpu-2gb, s-2vcpu-2gb, ... |
| os_image | Container Linux image for instances | "coreos-stable" | coreos-stable, coreos-beta, coreos-alpha, "custom-image-id" |
| controller_clc_snippets | Controller Container Linux Config snippets | [] | [example](/advanced/customization/) |
| worker_clc_snippets | Worker Container Linux Config snippets | [] | [example](/advanced/customization/) |
| networking | Choice of networking provider | "calico" | "flannel" or "calico" |
| pod_cidr | CIDR IPv4 range to assign to Kubernetes pods | "10.2.0.0/16" | "10.22.0.0/16" |
| service_cidr | CIDR IPv4 range to assign to Kubernetes services | "10.3.0.0/16" | "10.3.0.0/24" |

Check the list of valid [droplet types](https://developers.digitalocean.com/documentation/changelog/api-v2/new-size-slugs-for-droplet-plan-changes/) or use `doctl compute size list`.

!!! warning
    Do not choose a `controller_type` smaller than 2GB. Smaller droplets are not sufficient for running a controller and bootstrapping will fail.