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Dalton Hubble cd913986df Write documentation for Fedora Atomic

2018-04-24 01:10:27 -07:00

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Google Cloud

In this tutorial, we'll create a Kubernetes v1.10.1 cluster on Google Compute Engine with Container Linux.

We'll declare a Kubernetes cluster using the Typhoon Terraform module. Then apply the changes to create a network, firewall rules, health checks, controller instances, worker managed instance group, load balancers, and TLS assets.

Controllers are provisioned to run an etcd-member peer and a kubelet service. Workers run just a kubelet service. A one-time bootkube bootstrap schedules the apiserver, scheduler, controller-manager, and kube-dns on controllers and schedules kube-proxy and calico (or flannel) on every 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 a service account key. Choose the "Compute Engine Admin" role 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 = "1.6"
  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 Regions are listed in docs or with gcloud compute regions list. A project may contain multiple clusters across different regions.

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=v1.10.1"
  
  providers = {
    google   = "google.default"
    local    = "local.default"
    null     = "null.default"
    template = "template.default"
    tls      = "tls.default"
  }

  # Google Cloud
  cluster_name  = "yavin"
  region        = "us-central1"
  dns_zone      = "example.com"
  dns_zone_name = "example-zone"

  # configuration
  ssh_authorized_key = "ssh-rsa AAAAB3Nz..."
  asset_dir          = "/home/user/.secrets/clusters/yavin"
  
  # optional
  worker_count = 2
}

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

Apply

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

terraform init

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     v1.10.1
yavin-worker-jrbf.c.example-com.internal      Ready    5m     v1.10.1
yavin-worker-mzdm.c.example-com.internal      Ready    5m     v1.10.1

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

Check the variables.tf source.

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 user 'core'	"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 TCP proxy load balancer backed by controller instances. This FQDN is used by workers and kubectl to access the apiserver(s). In this example, the cluster's apiserver would be accessible at yavin.google-cloud.example.com.

You'll need a registered domain name or delegated subdomain on Google Cloud DNS. 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 delegate 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	3
worker_count	Number of workers	1	3
controller_type	Machine type for controllers	"n1-standard-1"	See below
worker_type	Machine type for workers	"n1-standard-1"	See below
os_image	Container Linux image for compute instances	"coreos-stable"	"coreos-stable-1632-3-0-v20180215"
disk_size	Size of the disk in GB	40	100
worker_preemptible	If enabled, Compute Engine will terminate workers randomly within 24 hours	false	true
controller_clc_snippets	Controller Container Linux Config snippets	[]
worker_clc_snippets	Worker Container Linux Config snippets	[]
networking	Choice of networking provider	"calico"	"calico" or "flannel"
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"
cluster_domain_suffix	FQDN suffix for Kubernetes services answered by kube-dns.	"cluster.local"	"k8s.example.com"

Check the list of valid machine types.

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.`

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