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249 lines
10 KiB
Markdown
249 lines
10 KiB
Markdown
# DigitalOcean
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In this tutorial, we'll create a Kubernetes v1.18.3 cluster on DigitalOcean with CoreOS Container Linux or Flatcar Linux.
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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.
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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.
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## Requirements
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* Digital Ocean Account and Token
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* Digital Ocean Domain (registered Domain Name or delegated subdomain)
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* Terraform v0.12.6+ and [terraform-provider-ct](https://github.com/poseidon/terraform-provider-ct) installed locally
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## Terraform Setup
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Install [Terraform](https://www.terraform.io/downloads.html) v0.12.6+ on your system.
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```sh
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$ terraform version
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Terraform v0.12.21
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```
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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.
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```sh
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wget https://github.com/poseidon/terraform-provider-ct/releases/download/v0.5.0/terraform-provider-ct-v0.5.0-linux-amd64.tar.gz
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tar xzf terraform-provider-ct-v0.5.0-linux-amd64.tar.gz
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mv terraform-provider-ct-v0.5.0-linux-amd64/terraform-provider-ct ~/.terraform.d/plugins/terraform-provider-ct_v0.5.0
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```
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Read [concepts](/architecture/concepts/) to learn about Terraform, modules, and organizing resources. Change to your infrastructure repository (e.g. `infra`).
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```
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cd infra/clusters
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```
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## Provider
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Login to [DigitalOcean](https://cloud.digitalocean.com) or create an [account](https://cloud.digitalocean.com/registrations/new), if you don't have one.
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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.
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```sh
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mkdir -p ~/.config/digital-ocean
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echo "TOKEN" > ~/.config/digital-ocean/token
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```
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Configure the DigitalOcean provider to use your token in a `providers.tf` file.
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```tf
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provider "digitalocean" {
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version = "1.18.0"
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token = "${chomp(file("~/.config/digital-ocean/token"))}"
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}
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provider "ct" {
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version = "0.5.0"
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}
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```
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### Flatcar Linux Images
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Flatcar Linux publishes DigitalOcean images, but does not yet upload them. DigitalOcean allows [custom images](https://blog.digitalocean.com/custom-images/) to be uploaded via URLor file.
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[Download](https://www.flatcar-linux.org/releases/) the Flatcar Linux DigitalOcean bin image. Rename the image with the channel and version (to refer to these images over time) and [upload](https://cloud.digitalocean.com/images/custom_images) it as a custom image.
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```tf
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data "digitalocean_image" "flatcar-stable-2303-4-0" {
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name = "flatcar-stable-2303.4.0.bin.bz2"
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}
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```
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Set the [os_image](#variables) in the next step.
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## Cluster
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Define a Kubernetes cluster using the module `digital-ocean/container-linux/kubernetes`.
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```tf
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module "nemo" {
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source = "git::https://github.com/poseidon/typhoon//digital-ocean/container-linux/kubernetes?ref=v1.18.3"
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# Digital Ocean
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cluster_name = "nemo"
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region = "nyc3"
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dns_zone = "digital-ocean.example.com"
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# configuration
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os_image = data.digitalocean_image.flatcar-stable-2303-4-0.id
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ssh_fingerprints = ["d7:9d:79:ae:56:32:73:79:95:88:e3:a2:ab:5d:45:e7"]
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# optional
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worker_count = 2
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}
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```
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Reference the [variables docs](#variables) or the [variables.tf](https://github.com/poseidon/typhoon/blob/master/digital-ocean/container-linux/kubernetes/variables.tf) source.
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## ssh-agent
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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`.
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```sh
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ssh-add ~/.ssh/id_rsa
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ssh-add -L
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```
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## Apply
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Initialize the config directory if this is the first use with Terraform.
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```sh
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terraform init
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```
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Plan the resources to be created.
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```sh
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$ terraform plan
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Plan: 54 to add, 0 to change, 0 to destroy.
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```
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Apply the changes to create the cluster.
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```sh
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$ terraform apply
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module.nemo.null_resource.bootstrap: Still creating... (30s elapsed)
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module.nemo.null_resource.bootstrap: Provisioning with 'remote-exec'...
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...
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module.nemo.null_resource.bootstrap: Still creating... (6m20s elapsed)
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module.nemo.null_resource.bootstrap: Creation complete (ID: 7599298447329218468)
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Apply complete! Resources: 42 added, 0 changed, 0 destroyed.
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```
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In 3-6 minutes, the Kubernetes cluster will be ready.
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## Verify
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[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).
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```
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resource "local_file" "kubeconfig-nemo" {
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content = module.nemo.kubeconfig-admin
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filename = "/home/user/.kube/configs/nemo-config"
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}
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```
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List nodes in the cluster.
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```
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$ export KUBECONFIG=/home/user/.kube/configs/nemo-config
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$ kubectl get nodes
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NAME STATUS ROLES AGE VERSION
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10.132.110.130 Ready <none> 10m v1.18.3
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10.132.115.81 Ready <none> 10m v1.18.3
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10.132.124.107 Ready <none> 10m v1.18.3
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```
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List the pods.
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```
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NAMESPACE NAME READY STATUS RESTARTS AGE
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kube-system coredns-1187388186-ld1j7 1/1 Running 0 11m
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kube-system coredns-1187388186-rdhf7 1/1 Running 0 11m
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kube-system calico-node-1m5bf 2/2 Running 0 11m
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kube-system calico-node-7jmr1 2/2 Running 0 11m
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kube-system calico-node-bknc8 2/2 Running 0 11m
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kube-system kube-apiserver-ip-10.132.115.81 1/1 Running 0 11m
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kube-system kube-controller-manager-ip-10.132.115.81 1/1 Running 0 11m
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kube-system kube-proxy-6kxjf 1/1 Running 0 11m
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kube-system kube-proxy-fh3td 1/1 Running 0 11m
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kube-system kube-proxy-k35rc 1/1 Running 0 11m
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kube-system kube-scheduler-ip-10.132.115.81 1/1 Running 0 11m
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```
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## Going Further
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Learn about [maintenance](/topics/maintenance/) and [addons](/addons/overview/).
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## Variables
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Check the [variables.tf](https://github.com/poseidon/typhoon/blob/master/digital-ocean/container-linux/kubernetes/variables.tf) source.
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### Required
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| Name | Description | Example |
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|:-----|:------------|:--------|
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| cluster_name | Unique cluster name (prepended to dns_zone) | "nemo" |
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| region | Digital Ocean region | "nyc1", "sfo2", "fra1", tor1" |
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| dns_zone | Digital Ocean domain (i.e. DNS zone) | "do.example.com" |
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| os_image | Container Linux image for instances | "custom-image-id", coreos-stable, coreos-beta, coreos-alpha |
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| ssh_fingerprints | SSH public key fingerprints | ["d7:9d..."] |
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#### DNS Zone
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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`.
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You'll need a registered domain name or delegated subdomain in DigitalOcean Domains (i.e. DNS zones). You can set this up once and create many clusters with unique names.
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```tf
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# Declare a DigitalOcean record to also create a zone file
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resource "digitalocean_domain" "zone-for-clusters" {
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name = "do.example.com"
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ip_address = "8.8.8.8"
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}
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```
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!!! tip ""
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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).
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#### SSH Fingerprints
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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,
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```bash
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ssh-keygen -E md5 -lf ~/.ssh/id_rsa.pub | awk '{print $2}'
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MD5:d7:9d:79:ae:56:32:73:79:95:88:e3:a2:ab:5d:45:e7
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```
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If you use `ssh-agent` (e.g. Yubikey for SSH), find the fingerprint with,
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```
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ssh-add -l -E md5
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2048 MD5:d7:9d:79:ae:56:32:73:79:95:88:e3:a2:ab:5d:45:e7 cardno:000603633110 (RSA)
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```
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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/).
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### Optional
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| Name | Description | Default | Example |
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| controller_count | Number of controllers (i.e. masters) | 1 | 1 |
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| worker_count | Number of workers | 1 | 3 |
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| controller_type | Droplet type for controllers | "s-2vcpu-2gb" | s-2vcpu-2gb, s-2vcpu-4gb, s-4vcpu-8gb, ... |
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| worker_type | Droplet type for workers | "s-1vcpu-2gb" | s-1vcpu-2gb, s-2vcpu-2gb, ... |
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| controller_snippets | Controller Container Linux Config snippets | [] | [example](/advanced/customization/) |
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| worker_snippets | Worker Container Linux Config snippets | [] | [example](/advanced/customization/) |
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| networking | Choice of networking provider | "calico" | "flannel" or "calico" |
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| pod_cidr | CIDR IPv4 range to assign to Kubernetes pods | "10.2.0.0/16" | "10.22.0.0/16" |
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| service_cidr | CIDR IPv4 range to assign to Kubernetes services | "10.3.0.0/16" | "10.3.0.0/24" |
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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`.
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!!! warning
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Do not choose a `controller_type` smaller than 2GB. Smaller droplets are not sufficient for running a controller and bootstrapping will fail.
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