# AWS

In this tutorial, we'll create a Kubernetes v1.9.1 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](https://github.com/kubernetes-incubator/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 v0.10.x and [terraform-provider-ct](https://github.com/coreos/terraform-provider-ct) installed locally

## Terraform Setup

Install [Terraform](https://www.terraform.io/downloads.html) v0.10.x on your system.

```sh
$ terraform version
Terraform v0.10.7
```

Add the [terraform-provider-ct](https://github.com/coreos/terraform-provider-ct) plugin binary for your system.

```sh
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](concepts.md) 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.

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

Additional configuration options are described in the `aws` provider [docs](https://www.terraform.io/docs/providers/aws/).

!!! tip
    Regions are listed in [docs](http://docs.aws.amazon.com/general/latest/gr/rande.html#ec2_region) or with `aws ec2 describe-regions`.

## Cluster

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

```tf
module "aws-tempest" {
  source = "git::https://github.com/poseidon/typhoon//aws/container-linux/kubernetes"

  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](#variables) or the [variables.tf](https://github.com/poseidon/typhoon/blob/master/aws/container-linux/kubernetes/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`.

```sh
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.

```sh
terraform init
```

Get or update Terraform modules.

```sh
$ 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=v0.9.1 (update)
```

Plan the resources to be created.

```sh
$ terraform plan
Plan: 98 to add, 0 to change, 0 to destroy.
```

Apply the changes to create the cluster.

```sh
$ 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](https://coreos.com/kubernetes/docs/latest/configure-kubectl.html) on your system. Use the generated `kubeconfig` credentials to access the Kubernetes cluster and list nodes.

```
$ KUBECONFIG=/home/user/.secrets/clusters/tempest/auth/kubeconfig
$ kubectl get nodes
NAME             STATUS    AGE       VERSION        
ip-10-0-12-221   Ready     34m       v1.9.1
ip-10-0-19-112   Ready     34m       v1.9.1
ip-10-0-4-22     Ready     34m       v1.9.1
```

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](concepts.md#versioning), maintenance, and [addons](addons/overview.md).

!!! 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.

```tf
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](http://docs.aws.amazon.com/Route53/latest/DeveloperGuide/SOA-NSrecords.html).

### 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](https://aws.amazon.com/ec2/instance-types/).

!!! tip "MTU"
    If your EC2 instance type supports [Jumbo frames](http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/network_mtu.html#jumbo_frame_instances) (most do), we recommend you change the `network_mtu` to 8991! You will get better pod-to-pod bandwidth.