cga-work / terraform-aws-eks

A Terraform module to Provision AWS Elastic Kubernetes (EKS) clusters and worker nodes

Terraform EKS Module

This repo contains a set of Terraform modules that can be used to provision an Elastic Kubernetes (EKS) cluster on AWS.

This module provides a way to provision an EKS cluster based on the current best practices employed by Cookpad's Global SRE team.

Using this module

We recommend setting up your cluster(s) using the submodules.

This will allow you to flexibly manage and grow the configuration of your cluster(s) over time, you can also pick and choose the parts of the configuration you want to manage with these modules.

This setup allows you to:

• Easily add (and remove) additional node groups to your cluster.
• Easily add additional clusters to your VPC.
• Provision a cluster to an existing VPC (assuming it has the correct subnets setup)

module "vpc" {
  source  = "cookpad/eks/aws//modules/vpc"
  version = "~> 1.19"

  name               = "us-east-1"
  cidr_block         = "10.4.0.0/16"
  availability_zones = ["us-east-1a", "us-east-1b", "us-east-1c"]
}

module "iam" {
  source  = "cookpad/eks/aws//modules/iam"
  version = "~> 1.19"
}


module "cluster" {
  source  = "cookpad/eks/aws//modules/cluster"
  version = "~> 1.19"

  name       = "hal-9000"

  vpc_config = module.vpc.config
  iam_config = module.iam.config
}

module "node_group" {
  source  = "cookpad/eks/aws//modules/asg_node_group"
  version = "~> 1.19"

  cluster_config = module.cluster.config

  max_size           = 60
  instance_family    = "burstable"
  instance_size      = "medium"
}

Requirements

In order to communicate with kubernetes correctly this module requires kubectl and the aws cli to be installed and on your path.

Note: We considered an approach using the kubernetes terraform provider. But this required multiple edit - plan - apply cycles to create a cluster. This module allows a cluster to be created and ready to use in a single PR.

Multi User Environments

In an environment where multiple IAM users are used to running terraform run and terraform apply it is recommended to use the assume role functionality to assume a common IAM role in the aws provider definition.

provider "aws" {
  region              = "us-east-1"
  version             = "3.53.0"
  assume_role {
    role_arn = "arn:aws:iam::<your account id>:role/Terraform"
  }
}

see an example role here

Without this you may encounter difficulties applying kubernetes manifests to the cluster.

Alternatively you should ensure that all users who need to run terraform are listed in the aws_auth_user_map variable of the cluster module.

Modules

vpc

This module provisions a VPC with public and private subnets suitable for launching an EKS cluster into.

iam

This module provisions the IAM roles and policies needed to run an EKS cluster and nodes.

cluster

This module provisions an EKS cluster, including the EKS Kubernetes control plane, and several important cluster services (critical addons), and nodes to run these services.

It will not provision any nodes that can be used to run non cluster services.

asg_node_group

This module provisions EC2 autoscaling groups that will make compute resources available, in order to run Kubernetes pods.