11 KiB

Raw Blame History

Google Cloud

In this tutorial, we'll create a Kubernetes v1.9.4 cluster on Google Compute Engine (not GKE).

We'll declare a Kubernetes cluster in Terraform using the Typhoon Terraform module. On apply, a network, firewall rules, managed instance groups of Kubernetes controllers and workers, network load balancers for controllers and workers, and health checks will be created.

Controllers and workers are provisioned to run a kubelet. A one-time bootkube bootstrap schedules an apiserver, scheduler, controller-manager, and kube-dns on controllers and runs kube-proxy and calico or flannel on each node. A generated kubeconfig provides kubectl access to the cluster.

Requirements

Google Cloud Account and Service Account
Google Cloud DNS Zone (registered Domain Name or delegated subdomain)
Terraform v0.11.x and terraform-provider-ct installed locally

Terraform Setup

Install Terraform v0.11.x on your system.

$ terraform version
Terraform v0.11.1

Add the terraform-provider-ct plugin binary for your system.

wget https://github.com/coreos/terraform-provider-ct/releases/download/v0.2.1/terraform-provider-ct-v0.2.1-linux-amd64.tar.gz
tar xzf terraform-provider-ct-v0.2.1-linux-amd64.tar.gz
sudo mv terraform-provider-ct-v0.2.1-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

Select "Credentials", and create service account key credentials. Choose the "Compute Engine default service account" and save the JSON private key to a file that can be referenced in configs.

mv ~/Downloads/project-id-43048204.json ~/.config/google-cloud/terraform.json

Configure the Google Cloud provider to use your service account key, project-id, and region in a providers.tf file.

provider "google" {
  version = "1.2"
  alias   = "default"

  credentials = "${file("~/.config/google-cloud/terraform.json")}"
  project     = "project-id"
  region      = "us-central1"
}

provider "local" {
  version = "~> 1.0"
  alias = "default"
}

provider "null" {
  version = "~> 1.0"
  alias = "default"
}

provider "template" {
  version = "~> 1.0"
  alias = "default"
}

provider "tls" {
  version = "~> 1.0"
  alias = "default"
}

Additional configuration options are described in the google provider docs.

!!! tip A project may contain multiple clusters if you wish. Regions are listed in docs or with gcloud compute regions list.

Cluster

Define a Kubernetes cluster using the module google-cloud/container-linux/kubernetes.

module "google-cloud-yavin" {
  source = "git::https://github.com/poseidon/typhoon//google-cloud/container-linux/kubernetes?ref=v1.9.4"
  
  providers = {
    google   = "google.default"
    local    = "local.default"
    null     = "null.default"
    template = "template.default"
    tls      = "tls.default"
  }

  # Google Cloud
  region        = "us-central1"
  dns_zone      = "example.com"
  dns_zone_name = "example-zone"
  os_image      = "coreos-stable"

  cluster_name       = "yavin"
  controller_count   = 1
  worker_count       = 2
  ssh_authorized_key = "ssh-rsa AAAAB3Nz..."

  # output assets dir
  asset_dir = "/home/user/.secrets/clusters/yavin"
}

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 terraform 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=v0.11.0 (update)

Plan the resources to be created.

$ terraform plan
Plan: 64 to add, 0 to change, 0 to destroy.

Apply the changes to create the cluster.

$ terraform apply
module.google-cloud-yavin.null_resource.bootkube-start: Still creating... (10s elapsed)
...

module.google-cloud-yavin.null_resource.bootkube-start: Still creating... (5m30s elapsed)
module.google-cloud-yavin.null_resource.bootkube-start: Still creating... (5m40s elapsed)
module.google-cloud-yavin.null_resource.bootkube-start: Creation complete (ID: 5768638456220583358)

Apply complete! Resources: 64 added, 0 changed, 0 destroyed.

In 4-8 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.

$ export KUBECONFIG=/home/user/.secrets/clusters/yavin/auth/kubeconfig
$ kubectl get nodes
NAME                                          STATUS   AGE    VERSION
yavin-controller-0.c.example-com.internal     Ready    6m     v1.9.4
yavin-worker-jrbf.c.example-com.internal      Ready    5m     v1.9.4
yavin-worker-mzdm.c.example-com.internal      Ready    5m     v1.9.4

List the pods.

$ kubectl get pods --all-namespaces
NAMESPACE     NAME                                      READY  STATUS    RESTARTS  AGE
kube-system   calico-node-1cs8z                         2/2    Running   0         6m
kube-system   calico-node-d1l5b                         2/2    Running   0         6m
kube-system   calico-node-sp9ps                         2/2    Running   0         6m
kube-system   kube-apiserver-zppls                      1/1    Running   0         6m
kube-system   kube-controller-manager-3271970485-gh9kt  1/1    Running   0         6m
kube-system   kube-controller-manager-3271970485-h90v8  1/1    Running   1         6m
kube-system   kube-dns-1187388186-zj5dl                 3/3    Running   0         6m
kube-system   kube-proxy-117v6                          1/1    Running   0         6m
kube-system   kube-proxy-9886n                          1/1    Running   0         6m
kube-system   kube-proxy-njn47                          1/1    Running   0         6m
kube-system   kube-scheduler-3895335239-5x87r           1/1    Running   0         6m
kube-system   kube-scheduler-3895335239-bzrrt           1/1    Running   1         6m
kube-system   pod-checkpointer-l6lrt                    1/1    Running   0         6m

Going Further

Learn about maintenance and addons.

!!! note On Container Linux clusters, install the CLUO 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)	"yavin"
region	Google Cloud region	"us-central1"
dns_zone	Google Cloud DNS zone	"google-cloud.example.com"
dns_zone_name	Google Cloud DNS zone name	"example-zone"
ssh_authorized_key	SSH public key for ~/.ssh_authorized_keys	"ssh-rsa AAAAB3NZ..."
asset_dir	Path to a directory where generated assets should be placed (contains secrets)	"/home/user/.secrets/clusters/yavin"

Check the list of valid regions and list Container Linux images with gcloud compute images list | grep coreos.

DNS Zone

Clusters create a DNS A record ${cluster_name}.${dns_zone} to resolve a network load balancer backed by controller instances. This FQDN is used by workers and kubectl to access the apiserver. In this example, the cluster's apiserver would be accessible at yavin.google-cloud.example.com.

You'll need a registered domain name or subdomain registered in a Google Cloud DNS zone. You can set this up once and create many clusters with unique names.

resource "google_dns_managed_zone" "zone-for-clusters" {
  dns_name    = "google-cloud.example.com."
  name        = "example-zone"
  description = "Production DNS zone"
}

!!! tip "" If you have an existing domain name with a zone file elsewhere, just carve out a subdomain that can be managed on Google Cloud (e.g. google-cloud.mydomain.com) and update nameservers.

Optional

Name	Description	Default	Example
controller_count	Number of controllers (i.e. masters)	1	1
worker_count	Number of workers	1	3
machine_type	Machine type for compute instances	"n1-standard-1"	See below
os_image	OS image for compute instances	"coreos-stable"	"coreos-stable-1632-3-0-v20180215"
worker_preemptible	If enabled, Compute Engine will terminate workers randomly within 24 hours	false	true
networking	Choice of networking provider	"calico"	"calico" or "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 assign to Kubernetes services	"10.3.0.0/16"	"10.3.0.0/24"
cluster_domain_suffix	FQDN suffix for Kubernetes services answered by kube-dns.	"cluster.local"	"k8s.example.com"
controller_clc_snippets	Controller Container Linux Config snippets	[]
worker_clc_snippets	Worker Container Linux Config snippets	[]

Check the list of valid machine types.

!!! warning Set controller_count to 1. A bug in Google Cloud network load balancer health checking prevents multiple controllers from bootstrapping. There are workarounds, but they all involve tradeoffs we're uncomfortable recommending. See #54.

Preemption

Add worker_preemeptible = "true" to allow worker nodes to be preempted at random, but pay significantly less. Clusters tolerate stopping instances fairly well (reschedules pods, but cannot drain) and preemption provides a nice reward for running fault-tolerant cluster systems.`

11 KiB Raw Blame History