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AWS

In this tutorial, we'll create a Kubernetes v1.9.3 cluster on AWS.

We'll declare a Kubernetes cluster in Terraform using the Typhoon Terraform module. On apply, a VPC, gateway, subnets, auto-scaling groups of controllers and workers, network load balancers for controllers and workers, and security groups 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

  • AWS Account and IAM credentials
  • AWS Route53 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/v0.2.0/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 your AWS IAM dashboard and find your IAM user. Select "Security Credentials" and create an access key. Save the id and secret to a file that can be referenced in configs.

[default]
aws_access_key_id = xxx
aws_secret_access_key = yyy

Configure the AWS provider to use your access key credentials in a providers.tf file.

provider "aws" {
  version = "~> 1.5.0"
  alias   = "default"

  region                  = "eu-central-1"
  shared_credentials_file = "/home/user/.config/aws/credentials"
}

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 aws provider docs.

!!! tip Regions are listed in docs or with aws ec2 describe-regions.

Cluster

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

module "aws-tempest" {
  source = "git::https://github.com/poseidon/typhoon//aws/container-linux/kubernetes?ref=v1.9.3"

  providers = {
    aws = "aws.default"
    local = "local.default"
    null = "null.default"
    template = "template.default"
    tls = "tls.default"
  }
  
  cluster_name = "tempest"

  # AWS
  dns_zone           = "aws.example.com"
  dns_zone_id        = "Z3PAABBCFAKEC0"
  controller_count   = 1
  controller_type    = "t2.medium"
  worker_count       = 2
  worker_type        = "t2.small"
  ssh_authorized_key = "ssh-rsa AAAAB3Nz..."

  # bootkube
  asset_dir  = "/home/user/.secrets/clusters/tempest"
}

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: 98 to add, 0 to change, 0 to destroy.

Apply the changes to create the cluster.

$ terraform apply
...
module.aws-tempest.null_resource.bootkube-start: Still creating... (4m50s elapsed)
module.aws-tempest.null_resource.bootkube-start: Still creating... (5m0s elapsed)
module.aws-tempest.null_resource.bootkube-start: Creation complete after 11m8s (ID: 3961816482286168143)

Apply complete! Resources: 98 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/tempest/auth/kubeconfig
$ kubectl get nodes
NAME             STATUS    AGE       VERSION        
ip-10-0-12-221   Ready     34m       v1.9.3
ip-10-0-19-112   Ready     34m       v1.9.3
ip-10-0-4-22     Ready     34m       v1.9.3

List the pods.

$ kubectl get pods --all-namespaces
NAMESPACE     NAME                                      READY  STATUS    RESTARTS  AGE              
kube-system   calico-node-1m5bf                         2/2    Running   0         34m              
kube-system   calico-node-7jmr1                         2/2    Running   0         34m              
kube-system   calico-node-bknc8                         2/2    Running   0         34m              
kube-system   kube-apiserver-4mjbk                      1/1    Running   0         34m              
kube-system   kube-controller-manager-3597210155-j2jbt  1/1    Running   1         34m              
kube-system   kube-controller-manager-3597210155-j7g7x  1/1    Running   0         34m              
kube-system   kube-dns-1187388186-wx1lg                 3/3    Running   0         34m              
kube-system   kube-proxy-14wxv                          1/1    Running   0         34m              
kube-system   kube-proxy-9vxh2                          1/1    Running   0         34m              
kube-system   kube-proxy-sbbsh                          1/1    Running   0         34m              
kube-system   kube-scheduler-3359497473-5plhf           1/1    Running   0         34m              
kube-system   kube-scheduler-3359497473-r7zg7           1/1    Running   1         34m              
kube-system   pod-checkpointer-4kxtl                    1/1    Running   0         34m              
kube-system   pod-checkpointer-4kxtl-ip-10-0-12-221     1/1    Running   0         33m

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) "tempest"
dns_zone AWS Route53 DNS zone "aws.example.com"
dns_zone_id AWS Route53 DNS zone id "Z3PAABBCFAKEC0"
ssh_authorized_key SSH public key for ~/.ssh_authorized_keys "ssh-rsa AAAAB3NZ..."
os_channel Container Linux AMI channel stable, beta, alpha
asset_dir Path to a directory where generated assets should be placed (contains secrets) "/home/user/.secrets/clusters/tempest"

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 tempest.aws.example.com.

You'll need a registered domain name or subdomain registered in a AWS Route53 DNS zone. You can set this up once and create many clusters with unique names.

resource "aws_route53_zone" "zone-for-clusters" {
  name = "aws.example.com."
}

Reference the DNS zone id with "${aws_route53_zone.zone-for-clusters.zone_id}".

!!! tip "" If you have an existing domain name with a zone file elsewhere, just carve out a subdomain that can be managed on Route53 (e.g. aws.mydomain.com) and update nameservers.

Optional

Name Description Default Example
controller_count Number of controllers (i.e. masters) 1 1
controller_type Controller EC2 instance type "t2.small" "t2.medium"
worker_count Number of workers 1 3
worker_type Worker EC2 instance type "t2.small" "t2.medium"
disk_size Size of the EBS volume in GB "40" "100"
networking Choice of networking provider "calico" "calico" or "flannel"
network_mtu CNI interface MTU (calico only) 1480 8981
host_cidr CIDR range to assign to EC2 instances "10.0.0.0/16" "10.1.0.0/16"
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"

Check the list of valid instance types.

!!! tip "MTU" If your EC2 instance type supports Jumbo frames (most do), we recommend you change the network_mtu to 8991! You will get better pod-to-pod bandwidth.