# AWS

In this tutorial, we'll create a Kubernetes v1.8.2 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 `etcd`, `apiserver`, `scheduler`, `controller-manager`, and `kube-dns` on controllers and runs `kube-proxy` and `flannel` or `calico` on each node. A generated `kubeconfig` provides `kubectl` access to the cluster.

!!! warning "Alpha"
    Typhoon Kubernetes clusters on AWS are marked as "alpha".

!!! warning "Disabled"
    Clusters do not use EC2 instances with elevated IAM roles. Kubernetes AWS integrations are not enabled.

## Requirements

* AWS Account and IAM credentials
* AWS Route53 DNS Zone (registered Domain Name or delegated subdomain)
* Terraform v0.10.4+ and [terraform-provider-ct](https://github.com/coreos/terraform-provider-ct) installed locally

## Terraform Setup

Install [Terraform](https://www.terraform.io/downloads.html) v0.10.1 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.small"
  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
    `terrafrom 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=v0.8.0 (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... (10m50s elapsed)
module.aws-tempest.null_resource.bootkube-start: Still creating... (11m0s elapsed)
module.aws-tempest.null_resource.bootkube-start: Creation complete after 11m8s (ID: 3961816482286168143)

Apply complete! Resources: 98 added, 0 changed, 0 destroyed.
```

In 10-20 minutes, the Kubernetes cluster will be ready.

!!! bug ""
    Typhoon clusters on AWS take much longer to create than clusters on other platforms. This is related to DNS resolution time to the ASG, which will be resolved in a future version that uses static controllers.

## 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       v1.8.2
ip-10-0-19-112   Ready     34m       v1.8.2
ip-10-0-4-22     Ready     34m       v1.8.2
```

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   etcd-operator-2287495111-br512            1/1    Running   1         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-etcd-0000                            1/1    Running   0         32m              
kube-system   kube-etcd-network-checkpointer-dt5pt      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-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 unqiue 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 assgin to Kubernetes services | "10.3.0.0/16" | "10.3.0.0/24" |

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.