This project is a modular Terraform infrastructure setup designed to provision and manage an EKS (Elastic Kubernetes Service) cluster with associated VPC (Virtual Private Cloud) and EFS (Elastic File System) resources. The structure follows a modular approach, with reusable components organized into separate directories.

Prerequisites

Before you begin, ensure that you have the following prerequisites in place:

• An AWS account with sufficient privileges to create and manage EKS resources

• AWS CLI installed and configured on your local machine

• Terraform installed locally (version 0.12 or above)

• Basic knowledge of Kubernetes and AWS services

Project Structure

Root Directory

The root directory contains the main Terraform configuration files for setting up the overarching infrastructure. It includes files for defining providers, shared variables, and outputs.

File	Description
main.tf	The primary entry point for Terraform configuration, orchestrating modules.
providers.tf	Defines provider configurations (e.g., AWS credentials and region settings).
variables.tf	Declares input variables shared across the project.
outputs.tf	Specifies output values for the infrastructure, including module outputs.
README.md	Provides a high-level overview of the project.

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efs/ Module

The efs module is responsible for provisioning Elastic File System (EFS) resources. This can include file systems, mount targets, and access points.

File	Description
main.tf	Contains the EFS-specific Terraform configurations.
variables.tf	Declares input variables required for the EFS module (e.g., file system size).
outputs.tf	Specifies output values related to EFS resources (e.g., file system IDs).

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eks/ Module

The eks module provisions an Elastic Kubernetes Service (EKS) cluster. This includes the cluster itself, worker nodes, and any associated IAM roles.

File	Description
main.tf	Contains the EKS-specific Terraform configurations.
variables.tf	Declares input variables for the EKS module (e.g., cluster name, node types).
outputs.tf	Specifies output values related to the EKS module (e.g., cluster endpoint).

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vpc/ Module

The vpc module handles the provisioning of the Virtual Private Cloud (VPC) infrastructure. It includes subnets, route tables, internet gateways, and NAT gateways.

File	Description
main.tf	Contains the VPC-specific Terraform configurations.
variables.tf	Declares input variables for the VPC module (e.g., CIDR blocks, subnet sizes).
outputs.tf	Specifies output values for VPC resources (e.g., VPC ID, subnet IDs).

Installation

Follow these steps to set up the EKS cluster using Terraform:

1. Initialize Terraform:

   terraform init

2. Create a Terraform execution plan*:

   terraform plan

3. Review the execution plan and ensure it aligns with your expectations.

4. Apply the Terraform configuration to create the EKS cluster:

   terraform apply

5. Wait for the provisioning process to complete. This may take several minutes.

6. Once the cluster is provisioned, retrieve the Kubernetes configuration:

   aws eks update-kubeconfig --name <cluster-name> --region <aws-region> --kubeconfig ~/.kube/config

7. Verify the cluster is functioning correctly:

   kubectl cluster-info

Variables Explanation

Below is a detailed explanation of the variables required for this project:

Variable Name	Type	Default Value	Description
region	string	"eu-central-1"	The AWS region where the infrastructure will be provisioned.
name	string	"anaoum"	A project-specific name used for tagging and identification of resources.
customer	string	"fys"	A customer-specific identifier used for tagging and resource organization.
public_cidrs	list(string)	["10.0.100.0/24", "10.0.101.0/24"]	The CIDR blocks for the public subnets within the VPC.
private_cidrs	list(string)	["10.0.102.0/24", "10.0.103.0/24"]	The CIDR blocks for the private subnets within the VPC.
vpc_id	string	"vpc-xxx"	The ID of the VPC where the resources will be created.
private_rtb_id	string	"rtb-yyy"	The ID of the private route table associated with the private subnets.
public_rtb_id	string	"rtb-zzz"	The ID of the public route table associated with the public subnets.
node_groups	list(object)	(See Below)	Configuration for EKS node groups, including instance types, disk size, and scaling limits.

Default Value for node_groups

The node_groups variable is a list of objects that define the configuration for EKS worker node groups. Each object includes the following fields:

• instance_types: A list of instance types (e.g., ["t3.medium"]) to be used in the node group.
• disk_size: The size of the disk (in GB) for each instance.
• desired_size: The desired number of instances in the node group.
• max_size: The maximum number of instances the node group can scale up to.
• min_size: The minimum number of instances in the node group.

Default Node Group Configuration:

[
  {
    instance_types = ["t3.medium"]
    disk_size      = 20
    desired_size   = 2
    max_size       = 5
    min_size       = 1
  },
  {
    instance_types = ["t3.large"]
    disk_size      = 30
    desired_size   = 1
    max_size       = 3
    min_size       = 1
  }
]

Then execute the plan command using the file: terraform plan -var-file=terraform.tfvars

Feel free to adjust these parameters and re-run the terraform apply command to update your cluster.

Post-Installation

There could be additional configurations to be made in order to faciliate some needs upon cluster's creation.

Provision access to IAM users

By default, only the AWS profile (keys) that will be used will have access to the cluster but other users may want to be able to have access to it.

To do so, you must ammend the aws-auth configMap to include them.

1. Fetch the existing configMap:

   kubectl get cm aws-auth -n kube-system -o yaml > aws-auth.yaml

2. Edit the file by including a mapUsers section:

   nano aws-auth.yaml

   apiVersion: v1
   data:
      mapRoles: |
         - groups:
            - system:bootstrappers
            - system:nodes
            rolearn: arn:aws:iam::555555555555:role/anaoum-eks-worker-nodes-role
            username: system:node:{{EC2PrivateDNSName}}
      mapUsers: |
         - "groups":
            - "system:masters"
            "userarn": "arn:aws:iam::555555555555:user/user1"
            "username": "user1"
         - "groups":
            - "system:masters"
            "userarn": "arn:aws:iam::555555555555:user/user2"
            "username": "user2"
   kind: ConfigMap
   metadata:
      creationTimestamp: "2023-08-04T09:40:00Z"
      name: aws-auth
      namespace: kube-system
      resourceVersion: "865"
      uid: 6dbed3da-1e44-4425-8ca4-96c4a6045b48

3. Apply the updated manifest:

   kubectl apply -f aws-auth.yaml