* Update from bootkube v0.6.2 to v0.7.0 * Use renamed terraform-render-bootkube. Renamed from bootkube-terraform to meet Terraform Module requirements
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Digital Ocean
In this tutorial, we'll create a Kubernetes v1.7.7 cluster on Digital Ocean.
We'll declare a Kubernetes cluster in Terraform using the Typhoon Terraform module. On apply, firewall rules, DNS records, tags, and droplets for Kubernetes controllers and workers will be created.
Controllers and workers are provisioned to run a kubelet
. A one-time bootkube bootstrap schedules etcd
, apiserver
, scheduler
, controller-manager
, and kube-dns
on controllers and runs kube-proxy
and flannel
on each 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 v0.10.1+ and terraform-provider-ct installed locally
Terraform Setup
Install Terraform v0.10.1+ on your system.
$ terraform version
Terraform v0.10.1
Add the terraform-provider-ct plugin binary for your system.
wget https://github.com/coreos/terraform-provider-ct/releases/download/v0.2.0/terraform-provider-ct-v0.2.0-linux-amd64.tar.gz
tar xzf terraform-provider-ct-v0.2.0-linux-amd64.tar.gz
sudo mv terraform-provider-ct-v0.2.0-linux-amd64/terraform-provider-ct /usr/local/bin/
Add the plugin to your ~/.terraformrc
.
providers {
ct = "/usr/local/bin/terraform-provider-ct"
}
Read concepts to learn about Terraform, modules, and organizing resources. Change to your infrastructure repository (e.g. infra
).
cd infra/clusters
Provider
Login to DigitalOcean or create an account, if you don't have one.
Generate a Personal Access Token with read/write scope from the API tab. Write the token to a file that can be referenced in configs.
mkdir -p ~/.config/digital-ocean
echo "TOKEN" > ~/.config/digital-ocean/token
Configure the DigitalOcean provider to use your token in a providers.tf
file.
provider "digitalocean" {
token = "${chomp(file("~/.config/digital-ocean/token"))}"
}
Cluster
Define a Kubernetes cluster using the module digital-ocean/container-linux/kubernetes
.
module "digital-ocean-nemo" {
source = "git::https://github.com/poseidon/typhoon//digital-ocean/container-linux/kubernetes"
region = "nyc3"
dns_zone = "digital-ocean.example.com"
cluster_name = "nemo"
image = "coreos-stable"
controller_count = 1
controller_type = "2gb"
worker_count = 2
worker_type = "512mb"
ssh_fingerprints = ["d7:9d:79:ae:56:32:73:79:95:88:e3:a2:ab:5d:45:e7"]
# output assets dir
asset_dir = "/home/user/.secrets/clusters/nemo"
}
Reference the variables docs or the variables.tf source.
ssh-agent
Initial bootstrapping requires bootkube.service
be started on one controller node. Terraform uses ssh-agent
to automate this step. Add your SSH private key to ssh-agent
.
ssh-add ~/.ssh/id_rsa
ssh-add -L
!!! warning
terrafrom apply
will hang connecting to a controller if ssh-agent
does not contain the SSH key.
Apply
Initialize the config directory if this is the first use with Terraform.
terraform init
Get or update Terraform modules.
$ terraform get # downloads missing modules
$ terraform get --update # updates all modules
Get: git::https://github.com/poseidon/typhoon (update)
Get: git::https://github.com/poseidon/bootkube-terraform.git?ref=v0.7.0 (update)
Plan the resources to be created.
$ terraform plan
Plan: 54 to add, 0 to change, 0 to destroy.
Apply the changes to create the cluster.
$ terraform apply
module.digital-ocean-nemo.null_resource.bootkube-start: Still creating... (30s elapsed)
module.digital-ocean-nemo.null_resource.bootkube-start: Provisioning with 'remote-exec'...
...
module.digital-ocean-nemo.null_resource.bootkube-start: Still creating... (6m20s elapsed)
module.digital-ocean-nemo.null_resource.bootkube-start: Creation complete (ID: 7599298447329218468)
Apply complete! Resources: 54 added, 0 changed, 0 destroyed.
In 5-10 minutes, the Kubernetes cluster will be ready.
Verify
Install kubectl on your system. Use the generated kubeconfig
credentials to access the Kubernetes cluster and list nodes.
$ KUBECONFIG=/home/user/.secrets/clusters/nemo/auth/kubeconfig
$ kubectl get nodes
NAME STATUS AGE VERSION
10.132.110.130 Ready 10m v1.7.7+coreos.0
10.132.115.81 Ready 10m v1.7.7+coreos.0
10.132.124.107 Ready 10m v1.7.7+coreos.0
List the pods.
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-system etcd-operator-3329263108-sgsbl 1/1 Running 1 11m
kube-system kube-apiserver-n10qr 1/1 Running 0 11m
kube-system kube-controller-manager-3271970485-37gtw 1/1 Running 1 11m
kube-system kube-controller-manager-3271970485-p52t5 1/1 Running 0 11m
kube-system kube-dns-1187388186-ld1j7 3/3 Running 0 11m
kube-system kube-etcd-0000 1/1 Running 0 9m
kube-system kube-etcd-network-checkpointer-n9xsk 1/1 Running 0 11m
kube-system kube-flannel-1cq1v 2/2 Running 0 11m
kube-system kube-flannel-hq9t0 2/2 Running 1 11m
kube-system kube-flannel-v0g9w 2/2 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-3895335239-2bc4c 1/1 Running 0 11m
kube-system kube-scheduler-3895335239-b7q47 1/1 Running 1 11m
kube-system pod-checkpointer-pr1lq 1/1 Running 0 11m
kube-system pod-checkpointer-pr1lq-10.132.115.81 1/1 Running 0 10m
Going Further
Learn about version pinning, maintenance, and addons.
!!! note
On Container Linux clusters, install the container-linux-update-operator
addon to coordinate reboots and drains when nodes auto-update. Otherwise, updates may not be applied until the next reboot.
Variables
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..."] |
asset_dir | Path to a directory where generated assets should be placed (contains secrets) | /home/user/.secrets/nemo |
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. In this example, the cluster's apiserver would be accessible at nemo.do.example.com
.
You'll need a registered domain name or subdomain registered in Digital Ocean Domains (i.e. DNS zones). You can set this up once and create many clusters with unqiue names.
resource "digitalocean_domain" "zone-for-clusters" {
name = "do.example.com"
# Digital Ocean oddly requires an IP here. You may have to delete the A record it makes. :(
ip_address = "8.8.8.8"
}
!!! tip "" If you have an existing domain name with a zone file elsewhere, just carve out a subdomain that can be managed on DigitalOcean (e.g. do.mydomain.com) and update nameservers.
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,
ssh-keygen -lf ~/.ssh/id_rsa.pub | awk '{print $2}'
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)
If you uploaded an SSH key to DigitalOcean (not required), find the fingerprint under Settings -> Security. Finally, if you don't have an SSH key, create one now.
Optional
Name | Description | Default | Example |
---|---|---|---|
image | OS image for droplets | "coreos-stable" | coreos-stable, coreos-beta, coreos-alpha |
controller_count | Number of controllers (i.e. masters) | 1 | 1 |
controller_type | Digital Ocean droplet size | 2gb | 2gb (min), 4gb, 8gb |
worker_count | Number of workers | 1 | 3 |
worker_type | Digital Ocean droplet size | 512mb | 512mb, 1gb, 2gb, 4gb |
networking | Choice of networking provider | "flannel" | "flannel" |
pod_cidr | CIDR range to assign to Kubernetes pods | "10.2.0.0/16" | "10.22.0.0/16" |
service_cidr | CIDR range to assgin to Kubernetes services | "10.3.0.0/16" | "10.3.0.0/24" |
!!! warning
Do not choose a controller_type
smaller than 2gb
. The 1gb
droplet is not sufficient for running a controller and bootstrapping will fail.
!!! bug
Digital Ocean firewalls do not yet support the IP tunneling (IP in IP) protocol used by Calico. You can try using "calico" for networking
, but it will only work if the cloud firewall is removed (unsafe).