## Kubernetes on AWS with Terraform

**Overview:**

This project will create:
* VPC with Public and Private Subnets in # Availability Zones
* Bastion Hosts and NAT Gateways in the Public Subnet
* A dynamic number of masters, etcd, and worker nodes in the Private Subnet
 * even distributed over the # of Availability Zones
* AWS ELB in the Public Subnet for accessing the Kubernetes API from the internet

**Requirements**
- Terraform 0.12.0 or newer

**How to Use:**

- Export the variables for your AWS credentials or edit `credentials.tfvars`:

```
export TF_VAR_AWS_ACCESS_KEY_ID="www"
export TF_VAR_AWS_SECRET_ACCESS_KEY ="xxx"
export TF_VAR_AWS_SSH_KEY_NAME="yyy"
export TF_VAR_AWS_DEFAULT_REGION="zzz"
```
- Update `contrib/terraform/aws/terraform.tfvars` with your data. By default, the Terraform scripts use Ubuntu 18.04 LTS (Bionic) as base image. If you want to change this behaviour, see note "Using other distrib than Ubuntu" below.
- Create an AWS EC2 SSH Key
- Run with `terraform apply --var-file="credentials.tfvars"` or `terraform apply` depending if you exported your AWS credentials

Example:
```commandline
terraform apply -var-file=credentials.tfvars
```

- Terraform automatically creates an Ansible Inventory file called `hosts` with the created infrastructure in the directory `inventory`

- Ansible will automatically generate an ssh config file for your bastion hosts. To connect to hosts with ssh using bastion host use generated ssh-bastion.conf.
  Ansible automatically detects bastion and changes ssh_args  
```commandline
ssh -F ./ssh-bastion.conf user@$ip
```

- Once the infrastructure is created, you can run the kubespray playbooks and supply inventory/hosts with the `-i` flag.

Example (this one assumes you are using Ubuntu)
```commandline
ansible-playbook -i ./inventory/hosts ./cluster.yml -e ansible_user=ubuntu -b --become-user=root --flush-cache
```
***Using other distrib than Ubuntu***
If you want to use another distribution than Ubuntu 18.04 (Bionic) LTS, you can modify the search filters of the 'data "aws_ami" "distro"' in variables.tf.

For example, to use:
- Debian Jessie, replace 'data "aws_ami" "distro"' in variables.tf with
data "aws_ami" "distro" {
  most_recent = true

  filter {
    name   = "name"
    values = ["debian-jessie-amd64-hvm-*"]
  }

  filter {
    name   = "virtualization-type"
    values = ["hvm"]
  }

  owners = ["379101102735"]
}

- Ubuntu 16.04, replace 'data "aws_ami" "distro"' in variables.tf with
data "aws_ami" "distro" {
  most_recent = true

  filter {
    name   = "name"
    values = ["ubuntu/images/hvm-ssd/ubuntu-xenial-16.04-amd64-*"]
  }

  filter {
    name   = "virtualization-type"
    values = ["hvm"]
  }

  owners = ["099720109477"]
}

- Centos 7, replace 'data "aws_ami" "distro"' in variables.tf with
data "aws_ami" "distro" {
  most_recent = true

  filter {
    name   = "name"
    values = ["dcos-centos7-*"]
  }

  filter {
    name   = "virtualization-type"
    values = ["hvm"]
  }

  owners = ["688023202711"]
}

**Troubleshooting**

***Remaining AWS IAM Instance Profile***:

If the cluster was destroyed without using Terraform it is possible that
the AWS IAM Instance Profiles still remain. To delete them you can use
the `AWS CLI` with the following command:
```
aws iam delete-instance-profile --region <region_name> --instance-profile-name <profile_name>
```

***Ansible Inventory doesn't get created:***

It could happen that Terraform doesn't create an Ansible Inventory file automatically. If this is the case copy the output after `inventory=` and create a file named `hosts`in the directory `inventory` and paste the inventory into the file.

**Architecture**

Pictured is an AWS Infrastructure created with this Terraform project distributed over two Availability Zones.

![AWS Infrastructure with Terraform  ](docs/aws_kubespray.png)
