Terraform AWS Base Infrastructure Module

Overview

This comprehensive Terraform module provisions a complete AWS infrastructure foundation including VPC, subnets, EKS cluster, node groups, bastion host, and VPC flow logs. It provides a production-ready, scalable base infrastructure for running containerized workloads on Amazon EKS.

Features

• Complete VPC setup with configurable CIDR blocks
• Dynamic subnet creation across multiple availability zones
• Public and private subnet configuration with NAT gateways
• VPC Flow Logs for network monitoring
• EC2 Bastion host for secure SSH access
• Amazon EKS cluster with configurable Kubernetes version
• EKS Node Groups with auto-scaling capabilities
• OIDC provider integration for IAM roles for service accounts
• Security groups and IAM roles properly configured
• CloudPosse naming conventions for consistent resource naming

Resources Created

Networking

• AWS VPC
• Internet Gateway
• NAT Gateways (one per AZ)
• Public and Private Subnets (dynamic across AZs)
• Route Tables
• VPC Flow Logs (CloudWatch Logs integration)

Compute

• EC2 Bastion Server with Elastic IP
• EKS Cluster
• EKS Node Group with Auto Scaling

Security

• Security Groups for bastion and EKS cluster
• IAM Roles and Policies for EKS cluster and worker nodes
• OIDC Identity Provider (optional)

Monitoring

• VPC Flow Logs with CloudWatch Log Group

Usage

module "base_infrastructure" {
  source = "git@github.com:webuildyourcloud/terraform-aws-base_infra.git"

  # Required Variables
  region              = "us-east-1"
  availability_zones  = ["us-east-1a", "us-east-1b", "us-east-1c"]
  vpc_cidr_block      = "10.0.0.0/16"

  # Naming Convention
  prefix              = "myorg"
  stage               = "prod"
  name                = "app"
  delimiter           = "-"
  attributes          = []

  # Bastion Configuration
  bastion_instance_type = "t3.micro"
  bastion_ami          = "ami-0c55b159cbfafe1f0"
  keyname              = "my-ssh-key"
  security_groups      = []

  # EKS Configuration
  kubernetes_version   = "1.21"
  instance_types       = ["t3.medium"]
  desired_size         = 3
  min_size             = 2
  max_size             = 5
  disk_size            = 20
  kubeconfig_path      = "./kubeconfig"
  oidc_provider_enabled = true

  # Kubernetes Labels
  kubernetes_labels = {
    Environment = "production"
    Team        = "platform"
  }

  # Tags
  tags = {
    Environment = "production"
    ManagedBy   = "terraform"
  }
}

Variables

Name	Description	Type	Default	Required
region	AWS Region	string	n/a	yes
availability_zones	List of availability zones	list(string)	n/a	yes
vpc_cidr_block	VPC CIDR block	string	n/a	yes
prefix	Namespace for the organization	string	n/a	yes
stage	Stage (e.g., 'prod', 'staging', 'dev')	string	n/a	yes
name	Solution name	string	n/a	yes
delimiter	Delimiter between name components	string	"-"	no
attributes	Additional attributes	list(string)	[]	no
tags	Additional tags	map(string)	{}	no
bastion_instance_type	EC2 instance type for bastion	string	n/a	yes
bastion_ami	AMI ID for bastion host	string	n/a	yes
keyname	SSH key name	string	""	no
security_groups	Security groups allowed to connect to bastion	list(string)	n/a	yes
user_data	User data content for bastion	list(string)	[]	no
root_block_device_encrypted	Encrypt root block device	bool	false	no
root_block_device_volume_size	Root block device volume size (GiB)	number	8	no
metadata_http_endpoint_enabled	Enable metadata service	bool	true	no
metadata_http_put_response_hop_limit	HTTP PUT response hop limit	number	1	no
metadata_http_tokens_required	Require metadata session tokens	bool	false	no
associate_public_ip_address	Associate public IP to bastion	bool	true	no
kubernetes_version	Kubernetes version	string	null	no
desired_size	Desired number of worker nodes	number	n/a	yes
max_size	Maximum number of worker nodes	number	n/a	yes
min_size	Minimum number of worker nodes	number	n/a	yes
oidc_provider_enabled	Create IAM OIDC provider	bool	true	no
kubeconfig_path	Path to kubeconfig file	string	n/a	yes
disk_size	Disk size in GiB for worker nodes	number	n/a	yes
instance_types	Instance types for EKS nodes	list(string)	n/a	yes
kubernetes_labels	Kubernetes labels for node group	map(string)	n/a	yes
kubernetes_namespace	Kubernetes namespace for Fargate	string	"kube-apps"	no
aws_eks_update_kubeconfig_additional_arguments	Additional arguments for kubeconfig update	string	null	no

Outputs

Name	Description
public_subnet_cidrs	Public subnet CIDRs
private_subnet_cidrs	Private subnet CIDRs
public_subnet_ids	Public subnet IDs
private_subnet_ids	Private subnet IDs
vpc_cidr_block	VPC CIDR block
vpc_id	VPC ID
security_groups	Security Group IDs of bastion
eks_cluster_id	EKS cluster name
eks_cluster_arn	EKS cluster ARN
eks_cluster_endpoint	Kubernetes API server endpoint
eks_cluster_version	Kubernetes server version
eks_cluster_identity_oidc_issuer	OIDC Identity issuer
eks_cluster_certificate_authority_data	EKS cluster CA certificate
eks_cluster_auth_token	Cluster authentication token
workers_security_group_ids	Worker nodes security group
eks_node_group_role_arn	Worker nodes IAM role ARN
eks_node_group_role_name	Worker nodes IAM role name
eks_node_group_id	EKS Node Group ID
eks_node_group_arn	EKS Node Group ARN
eks_node_group_resources	Node Group underlying resources
eks_node_group_status	Node Group status

Requirements

Name	Version
terraform	>= 0.13
aws	~> 3.27

Dependencies

This module uses the following external modules:

• cloudposse/terraform-null-label - Resource naming
• cloudposse/vpc/aws - VPC creation
• umotif-public/vpc-flow-logs/aws - VPC Flow Logs
• cloudposse/dynamic-subnets/aws - Dynamic subnet creation
• cloudposse/ec2-bastion-server/aws - Bastion host
• Custom modules:
  • terraform-aws-eks-cluster
  • terraform-aws-eks_node_group

Important Notes

1. SSH Key: Ensure the SSH key specified in keyname exists in the target region before applying
2. VPC CIDR: Choose a CIDR block that doesn't conflict with other VPCs in your environment
3. NAT Gateways: This module creates NAT gateways which incur hourly charges
4. EKS Cluster: Initial cluster creation takes approximately 10-15 minutes
5. OIDC Provider: Enable OIDC provider for using IAM roles for Kubernetes service accounts
6. Kubeconfig: The module expects a path where it can write the kubeconfig file
7. Security Groups: Additional security groups can be attached to the bastion host via the security_groups variable

Security Considerations

• VPC Flow Logs are enabled by default for network monitoring
• Bastion host is configured in public subnets with restricted security groups
• EKS cluster and worker nodes are deployed in private subnets
• IMDSv2 can be enforced via metadata_http_tokens_required
• Root volume encryption can be enabled via root_block_device_encrypted

License

This module is provided as-is for use within your organization.