9.6 KiB
AWS
In this tutorial, we'll create a Kubernetes v1.18.4 cluster on AWS with CoreOS Container Linux or Flatcar Linux.
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 v0.12.6+ and terraform-provider-ct installed locally
Terraform Setup
Install Terraform v0.12.6+ on your system.
$ terraform version
Terraform v0.12.21
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/v0.5.0/terraform-provider-ct-v0.5.0-linux-amd64.tar.gz
tar xzf terraform-provider-ct-v0.5.0-linux-amd64.tar.gz
mv terraform-provider-ct-v0.5.0-linux-amd64/terraform-provider-ct ~/.terraform.d/plugins/terraform-provider-ct_v0.5.0
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 = "2.63.0"
region = "eu-central-1"
shared_credentials_file = "/home/user/.config/aws/credentials"
}
provider "ct" {
version = "0.5.0"
}
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/container-linux/kubernetes.
module "tempest" {
source = "git::https://github.com/poseidon/typhoon//aws/container-linux/kubernetes?ref=v1.18.4"
# AWS
cluster_name = "tempest"
dns_zone = "aws.example.com"
dns_zone_id = "Z3PAABBCFAKEC0"
# configuration
ssh_authorized_key = "ssh-rsa AAAAB3Nz..."
# 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: 80 to add, 0 to change, 0 to destroy.
Apply the changes to create the cluster.
$ terraform apply
...
module.tempest.null_resource.bootstrap: Still creating... (4m50s elapsed)
module.tempest.null_resource.bootstrap: Still creating... (5m0s elapsed)
module.tempest.null_resource.bootstrap: 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. Obtain the generated cluster kubeconfig from module outputs (e.g. write to a local file).
resource "local_file" "kubeconfig-tempest" {
content = module.tempest.kubeconfig-admin
filename = "/home/user/.kube/configs/tempest-config"
}
List nodes in the cluster.
$ export KUBECONFIG=/home/user/.kube/configs/tempest-config
$ kubectl get nodes
NAME STATUS ROLES AGE VERSION
ip-10-0-3-155 Ready <none> 10m v1.18.4
ip-10-0-26-65 Ready <none> 10m v1.18.4
ip-10-0-41-21 Ready <none> 10m v1.18.4
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..." |
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 a Container Linux derivative | "flatcar-stable" | coreos-stable, coreos-beta, coreos-alpha, flatcar-stable, flatcar-beta, flatcar-alpha, flatcar-edge |
| 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 worker instances or 0 to use on-demand instances | 0/null | 0.10 |
| controller_snippets | Controller Container Linux Config snippets | [] | example |
| worker_snippets | Worker Container Linux Config snippets | [] | example |
| 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" |
| worker_node_labels | List of initial worker node labels | [] | ["worker-pool=default"] |
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.