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AWS

!!! danger Typhoon for Fedora CoreOS is an early preview! Fedora CoreOS itself is a preview! Expect bugs and design shifts. Please help both projects solve problems. Report Fedora CoreOS bugs to Fedora. Report Typhoon issues to Typhoon.

In this tutorial, we'll create a Kubernetes v1.16.0 cluster on AWS with Fedora CoreOS.

We'll declare a Kubernetes cluster using the Typhoon Terraform module. Then apply the changes to create a VPC, gateway, subnets, security groups, controller instances, worker auto-scaling group, network load balancer, and TLS assets.

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.

Requirements

  • AWS Account and IAM credentials
  • AWS Route53 DNS Zone (registered Domain Name or delegated subdomain)
  • Terraform v0.12.x and terraform-provider-ct installed locally

Terraform Setup

Install Terraform v0.12.x on your system.

$ terraform version
Terraform v0.12.7

Add the terraform-provider-ct plugin binary for your system to ~/.terraform.d/plugins/, noting the final name.

wget https://github.com/poseidon/terraform-provider-ct/releases/download/v0.4.0/terraform-provider-ct-v0.4.0-linux-amd64.tar.gz
tar xzf terraform-provider-ct-v0.4.0-linux-amd64.tar.gz
mv terraform-provider-ct-v0.4.0-linux-amd64/terraform-provider-ct ~/.terraform.d/plugins/terraform-provider-ct_v0.4.0

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                 = "2.29.0"
  region                  = "us-east-1"   # MUST be us-east-1 right now!
  shared_credentials_file = "/home/user/.config/aws/credentials"
}

provider "ct" {
  version = "0.4.0"
}

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/fedora-coreos/kubernetes.

module "aws-tempest" {
  source = "git::https://github.com/poseidon/typhoon//aws/fedora-coreos/kubernetes?ref=DEVELOPMENT_SHA"

  # AWS
  cluster_name = "tempest"
  dns_zone     = "aws.example.com"
  dns_zone_id  = "Z3PAABBCFAKEC0"

  # configuration
  ssh_authorized_key = "ssh-rsa AAAAB3Nz..."
  asset_dir          = "/home/user/.secrets/clusters/tempest"

  # optional
  worker_count = 2
  worker_type  = "t3.small"
}

Reference the variables docs or the variables.tf source.

ssh-agent

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.

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

Apply the changes to create the cluster.

$ terraform apply
...
module.aws-tempest.null_resource.bootstrap: Still creating... (4m50s elapsed)
module.aws-tempest.null_resource.bootstrap: Still creating... (5m0s elapsed)
module.aws-tempest.null_resource.bootstrap: Creation complete after 5m8s (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  ROLES    AGE  VERSION
ip-10-0-3-155  Ready   <none>   10m  v1.16.0
ip-10-0-26-65  Ready   <none>   10m  v1.16.0
ip-10-0-41-21  Ready   <none>   10m  v1.16.0

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   coredns-1187388186-wx1lg               1/1    Running   0         34m
kube-system   coredns-1187388186-qjnvp               1/1    Running   0         34m
kube-system   kube-apiserver-ip-10-0-3-155           1/1    Running   0         34m
kube-system   kube-controller-manager-ip-10-0-3-155  1/1    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-ip-10-0-3-155           1/1    Running   1         34m

Going Further

Learn about maintenance and addons.

Variables

Check the variables.tf source.

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 user 'core' "ssh-rsa AAAAB3NZ..."
asset_dir Absolute 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(s). In this example, the cluster's apiserver would be accessible at tempest.aws.example.com.

You'll need a registered domain name or delegated subdomain on AWS Route53. 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 delegate 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
worker_count Number of workers 1 3
controller_type EC2 instance type for controllers "t3.small" See below
worker_type EC2 instance type for workers "t3.small" See below
os_image AMI channel for Fedora CoreOS not yet used ?
disk_size Size of the EBS volume in GB "40" "100"
disk_type Type of the EBS volume "gp2" standard, gp2, io1
disk_iops IOPS of the EBS volume "0" (i.e. auto) "400"
worker_target_groups Target group ARNs to which worker instances should be added [] ["${aws_lb_target_group.app.id}"]
worker_price Spot price in USD for workers. Leave as default empty string for regular on-demand instances "" "0.10"
controller_snippets Controller Fedora CoreOS Config snippets [] UNSUPPORTED
worker_clc_snippets Worker Fedora CoreOS Config snippets [] UNSUPPORTED
networking Choice of networking provider "calico" "calico" or "flannel"
network_mtu CNI interface MTU (calico only) 1480 8981
host_cidr CIDR IPv4 range to assign to EC2 instances "10.0.0.0/16" "10.1.0.0/16"
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 coredns. "cluster.local" "k8s.example.com"

Check the list of valid instance types.

!!! warning Do not choose a controller_type smaller than t2.small. Smaller instances are not sufficient for running a controller.

!!! tip "MTU" If your EC2 instance type supports Jumbo frames (most do), we recommend you change the network_mtu to 8981! You will get better pod-to-pod bandwidth.

Spot

Add worker_price = "0.10" to use spot instance workers (instead of "on-demand") and set a maximum spot price in USD. Clusters can tolerate spot market interuptions fairly well (reschedules pods, but cannot drain) to save money, with the tradeoff that requests for workers may go unfulfilled.