# Google Cloud

In this tutorial, we'll create a Kubernetes v1.17.3 cluster on Google Compute Engine 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 network, firewall rules, health checks, controller instances, worker managed instance group, load balancers, 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

* Google Cloud Account and Service Account
* Google Cloud DNS Zone (registered Domain Name or delegated subdomain)
* Terraform v0.12.6+ and [terraform-provider-ct](https://github.com/poseidon/terraform-provider-ct) installed locally

## Terraform Setup

Install [Terraform](https://www.terraform.io/downloads.html) v0.12.6+ on your system.

```sh
$ terraform version
Terraform v0.12.20
```

Add the [terraform-provider-ct](https://github.com/poseidon/terraform-provider-ct) plugin binary for your system to `~/.terraform.d/plugins/`, noting the final name.

```sh
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](/architecture/concepts/) to learn about Terraform, modules, and organizing resources. Change to your infrastructure repository (e.g. `infra`).

```
cd infra/clusters
```

## Provider

Login to your Google Console [API Manager](https://console.cloud.google.com/apis/dashboard) and select a project, or [signup](https://cloud.google.com/free/) if you don't have an account.

Select "Credentials" and create a service account key. Choose the "Compute Engine Admin" and "DNS Administrator" roles and save the JSON private key to a file that can be referenced in configs.

```sh
mv ~/Downloads/project-id-43048204.json ~/.config/google-cloud/terraform.json
```

Configure the Google Cloud provider to use your service account key, project-id, and region in a `providers.tf` file.

```tf
provider "google" {
  version     = "3.7.0"
  project     = "project-id"
  region      = "us-central1"
  credentials = file("~/.config/google-cloud/terraform.json")
}

provider "ct" {
  version = "0.4.0"
}
```

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

!!! tip
    Regions are listed in [docs](https://cloud.google.com/compute/docs/regions-zones/regions-zones) or with `gcloud compute regions list`. A project may contain multiple clusters across different regions.

## Cluster

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

```tf
module "yavin" {
  source = "git::https://github.com/poseidon/typhoon//google-cloud/container-linux/kubernetes?ref=v1.17.3"

  # Google Cloud
  cluster_name  = "yavin"
  region        = "us-central1"
  dns_zone      = "example.com"
  dns_zone_name = "example-zone"

  # configuration
  ssh_authorized_key = "ssh-rsa AAAAB3Nz..."

  # optional
  worker_count = 2
}
```

Reference the [variables docs](#variables) or the [variables.tf](https://github.com/poseidon/typhoon/blob/master/google-cloud/container-linux/kubernetes/variables.tf) source.

### Flatcar Linux Images

!!! success
    Skip this section when using CoreOS Container Linux (default). CoreOS Container Linux publishes official images to Google Cloud.

!!! danger
    Typhoon for Flatcar Linux on Google Cloud is alpha.

Flatcar Linux publishes images for Google Cloud, but does not yet upload them. Google Cloud allows [custom boot images](https://cloud.google.com/compute/docs/images/import-existing-image) to be uploaded to a bucket and imported into your project.

[Download](https://www.flatcar-linux.org/releases/) the Flatcar Linux GCE gzipped tarball and upload it to a Google Cloud storage bucket.

```
gsutil list
gsutil cp flatcar_production_gce.tar.gz gs://BUCKET
```

Create a Compute Engine image from the file.

```
gcloud compute images create flatcar-linux-2303-4-0 --source-uri gs://BUCKET_NAME/flatcar_production_gce.tar.gz
```

Set the [os_image](#variables) to the image name (e.g. `flatcar-linux-2303-4-0`)

## 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`.

```sh
ssh-add ~/.ssh/id_rsa
ssh-add -L
```

## Apply

Initialize the config directory if this is the first use with Terraform.

```sh
terraform init
```

Plan the resources to be created.

```sh
$ terraform plan
Plan: 64 to add, 0 to change, 0 to destroy.
```

Apply the changes to create the cluster.

```sh
$ terraform apply
module.yavin.null_resource.bootstrap: Still creating... (10s elapsed)
...
module.yavin.null_resource.bootstrap: Still creating... (5m30s elapsed)
module.yavin.null_resource.bootstrap: Still creating... (5m40s elapsed)
module.yavin.null_resource.bootstrap: Creation complete (ID: 5768638456220583358)

Apply complete! Resources: 62 added, 0 changed, 0 destroyed.
```

In 4-8 minutes, the Kubernetes cluster will be ready.

## Verify

[Install kubectl](https://kubernetes.io/docs/tasks/tools/install-kubectl/) on your system. Obtain the generated cluster `kubeconfig` from module outputs (e.g. write to a local file).

```
resource "local_file" "kubeconfig-yavin" {
  content  = module.yavin.kubeconfig-admin
  filename = "/home/user/.kube/configs/yavin-config"
}
```

List nodes in the cluster.

```
$ export KUBECONFIG=/home/user/.kube/configs/yavin-config
$ kubectl get nodes
NAME                                       ROLES    STATUS  AGE  VERSION
yavin-controller-0.c.example-com.internal  <none>   Ready   6m   v1.17.3
yavin-worker-jrbf.c.example-com.internal   <none>   Ready   5m   v1.17.3
yavin-worker-mzdm.c.example-com.internal   <none>   Ready   5m   v1.17.3
```

List the pods.

```
$ kubectl get pods --all-namespaces
NAMESPACE     NAME                                      READY  STATUS    RESTARTS  AGE
kube-system   calico-node-1cs8z                         2/2    Running   0         6m
kube-system   calico-node-d1l5b                         2/2    Running   0         6m
kube-system   calico-node-sp9ps                         2/2    Running   0         6m
kube-system   coredns-1187388186-dkh3o                  1/1    Running   0         6m
kube-system   coredns-1187388186-zj5dl                  1/1    Running   0         6m
kube-system   kube-apiserver-controller-0               1/1    Running   0         6m
kube-system   kube-controller-manager-controller-0      1/1    Running   0         6m
kube-system   kube-proxy-117v6                          1/1    Running   0         6m
kube-system   kube-proxy-9886n                          1/1    Running   0         6m
kube-system   kube-proxy-njn47                          1/1    Running   0         6m
kube-system   kube-scheduler-controller-0               1/1    Running   0         6m
```

## Going Further

Learn about [maintenance](/topics/maintenance/) and [addons](/addons/overview/).

!!! note
    On Container Linux clusters, install the `CLUO` addon to coordinate reboots and drains when nodes auto-update. Otherwise, updates may not be applied until the next reboot.

## Variables

Check the [variables.tf](https://github.com/poseidon/typhoon/blob/master/google-cloud/container-linux/kubernetes/variables.tf) source.

### Required

| Name | Description | Example |
|:-----|:------------|:--------|
| cluster_name | Unique cluster name (prepended to dns_zone) | "yavin" |
| region | Google Cloud region | "us-central1" |
| dns_zone | Google Cloud DNS zone | "google-cloud.example.com" |
| dns_zone_name | Google Cloud DNS zone name | "example-zone" |
| ssh_authorized_key | SSH public key for user 'core' | "ssh-rsa AAAAB3NZ..." |

Check the list of valid [regions](https://cloud.google.com/compute/docs/regions-zones/regions-zones) and list Container Linux [images](https://cloud.google.com/compute/docs/images) with `gcloud compute images list | grep coreos`.

#### DNS Zone

Clusters create a DNS A record `${cluster_name}.${dns_zone}` to resolve a TCP proxy 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 `yavin.google-cloud.example.com`.

You'll need a registered domain name or delegated subdomain on Google Cloud DNS. You can set this up once and create many clusters with unique names.

```tf
resource "google_dns_managed_zone" "zone-for-clusters" {
  dns_name    = "google-cloud.example.com."
  name        = "example-zone"
  description = "Production DNS zone"
}
```

!!! tip ""
    If you have an existing domain name with a zone file elsewhere, just delegate a subdomain that can be managed on Google Cloud (e.g. google-cloud.mydomain.com) and [update nameservers](https://cloud.google.com/dns/update-name-servers).

### Optional

| Name | Description | Default | Example |
|:-----|:------------|:--------|:--------|
| asset_dir | Absolute path to a directory where generated assets should be placed (contains secrets) | "" (disabled) | "/home/user/.secrets/clusters/yavin" |
| controller_count | Number of controllers (i.e. masters) | 1 | 3 |
| worker_count | Number of workers | 1 | 3 |
| controller_type | Machine type for controllers | "n1-standard-1" | See below |
| worker_type | Machine type for workers | "n1-standard-1" | See below |
| os_image | Container Linux image for compute instances | "coreos-stable" | "flatcar-linux-2303-4-0" |
| disk_size | Size of the disk in GB | 40 | 100 |
| worker_preemptible | If enabled, Compute Engine will terminate workers randomly within 24 hours | false | true |
| controller_clc_snippets | Controller Container Linux Config snippets | [] | [example](/advanced/customization/) |
| worker_clc_snippets | Worker Container Linux Config snippets | [] | [example](/advanced/customization/) |
| networking | Choice of networking provider | "calico" | "calico" or "flannel" |
| 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 [machine types](https://cloud.google.com/compute/docs/machine-types).

#### Preemption

Add `worker_preemptible = "true"` to allow worker nodes to be [preempted](https://cloud.google.com/compute/docs/instances/preemptible) at random, but pay [significantly](https://cloud.google.com/compute/pricing) less. Clusters tolerate stopping instances fairly well (reschedules pods, but cannot drain) and preemption provides a nice reward for running fault-tolerant cluster systems.`