terraform-aws-eks-cluster

Terraform module to provision an EKS cluster on AWS.

This project is part of our comprehensive "SweetOps" approach towards DevOps.

It's 100% Open Source and licensed under the APACHE2.

We literally have hundreds of terraform modules that are Open Source and well-maintained. Check them out!

Introduction

The module provisions the following resources:

• EKS cluster of master nodes that can be used together with the terraform-aws-eks-workers,terraform-aws-eks-node-group andterraform-aws-eks-fargate-profilemodules to create a full-blown cluster
• IAM Role to allow the cluster to access other AWS services
• Security Group which is used by EKS workers to connect to the cluster and kubelets and pods to receive communication from the cluster control plane
• The module creates and automatically applies an authentication ConfigMap to allow the workers nodes to join the cluster and to add additional users/roles/accounts

NOTE: The module works with Terraform Cloud.

NOTE: Every Terraform module that provisions an EKS cluster has faced the challenge that access to the clusteris partly controlled by a resource inside the cluster, a ConfigMap called aws-auth. You need to be able to accessthe cluster through the Kubernetes API to modify the ConfigMap, because there is no AWS API for it. This presentsa problem: how do you authenticate to an API endpoint that you have not yet created?

We use the Terraform Kubernetes provider to access the cluster, and it uses the same underlying librarythat kubectl uses, so configuration is very similar. However, every kind of configuration we have triedhas failed at some point.

• After creating the EKS cluster, we can generate a kubeconfig file that configures access to it.This works most of the time, but if the file was present and used as part of the configuration to createthe cluster, and then the file is deleted (as would happen in a CI system like Terraform Cloud), Terraformwould not cause the file to be regenerated in time to use it to refresh Terraform's state and the "plan" phase will fail.
• An authentication token can be retrieved using the aws_eks_cluster_auth data source. Again, this works, aslong as the token does not expire while Terraform is running, and the token is refreshed during the "plan"phase before trying to refresh the state. Unfortunately, failures of both types have been seen.
• An authentication token can be retrieved on demand by using the exec feature of the Kubernetes providerto call aws eks get-token. This requires that the aws CLI be installed and available to Terraform and that ithas access to sufficient credentials to perform the authentication and is configured to use them.

All of the above methods can face additional challenges when using terraform import to importresources into the Terraform state. The KUBECONFG file is the most reliable, and probably what youwould want to use when importing objects if your usual method does not work. You will need to createthe file, of course, but that is easily done with aws eks update-kubeconfig.

At the moment, the exec option appears to be the most reliable method, so we recommend using it if possible,but because of the extra requirements it has, we use the data source as the default authentication method.

NOTE: We give you the kubernetes_config_map_ignore_role_changes option and default it to true for the following reasons:

• We provision the EKS cluster
• Then we wait for the cluster to become available (see null_resource.wait_for_cluster in auth.tf
• Then we provision the Kubernetes Auth ConfigMap to map and add additional roles/users/accounts to Kubernetes groups
• That is all we do in this module, but after that, we expect you to use terraform-aws-eks-node-groupto provision a managed Node Group
• Then EKS updates the Auth ConfigMap and adds worker roles to it (for the worker nodes to join the cluster)
• Since the ConfigMap is modified outside of Terraform state, Terraform wants to update it to to remove the worker roles EKS added
• If you update the ConfigMap without including the worker nodes that EKS added, you will disconnect them from the cluster

However, it is possible to get the worker node roles from the terraform-aws-eks-node-group via Terraform "remote state"and include them with any other roles you want to add (example code to be published later), so we makeignoring the role changes optional. If you do not ignore changes then you will have no problem with making future intentional changes.

The downside of having kubernetes_config_map_ignore_role_changes set to true is that if you later want to make changes,such as adding other IAM roles to Kubernetes groups, you cannot do so via Terraform, because the role changes are ignored.Because of Terraform restrictions, you cannot simply change kubernetes_config_map_ignore_role_changes from trueto false, apply changes, and set it back to true again. Terraform does not allow the"ignore" settings to be changed on a resource, so kubernetes_config_map_ignore_role_changes is implemented as2 different resources, one with ignore settings and one without. If you want to switch from ignoring to not ignoring,or vice versa, you must manually move the aws_auth resource in the terraform state. Change the setting ofkubernetes_config_map_ignore_role_changes, run terraform plan, and you will see that an aws_auth resourceis planned to be destroyed and another one is planned to be created. Use terraform state mv to move the destroyedresource to the created resource "address", something like

terraform state mv 'module.eks_cluster.kubernetes_config_map.aws_auth_ignore_changes[0]' 'module.eks_cluster.kubernetes_config_map.aws_auth[0]'

Then run terraform plan again and you should see only your desired changes made "in place". After applying yourchanges, if you want to set kubernetes_config_map_ignore_role_changes back to true, you will again need to useterraform state mv to move the auth-map back to its old "address".

Security & Compliance

Security scanning is graciously provided by Bridgecrew. Bridgecrew is the leading fully hosted, cloud-native solution providing continuous Terraform security and compliance.

Usage

IMPORTANT: We do not pin modules to versions in our examples because of thedifficulty of keeping the versions in the documentation in sync with the latest released versions.We highly recommend that in your code you pin the version to the exact version you areusing so that your infrastructure remains stable, and update versions in asystematic way so that they do not catch you by surprise.

Also, because of a bug in the Terraform registry (hashicorp/terraform#21417),the registry shows many of our inputs as required when in fact they are optional.The table below correctly indicates which inputs are required.

For a complete example, see examples/complete.

For automated tests of the complete example using bats and Terratest (which tests and deploys the example on AWS), see test.

Other examples:

• terraform-root-modules/eks - Cloud Posse's service catalog of "root module" invocations for provisioning reference architectures
• terraform-root-modules/eks-backing-services-peering - example of VPC peering between the EKS VPC and backing services VPC

provider "aws" {
    region = var.region
  }

  module "label" {
    source = "cloudposse/label/null"
    # Cloud Posse recommends pinning every module to a specific version
    # version     = "x.x.x"
    namespace  = var.namespace
    name       = var.name
    stage      = var.stage
    delimiter  = var.delimiter
    attributes = compact(concat(var.attributes, ["cluster"]))
    tags       = var.tags
  }

  locals {
    # Prior to Kubernetes 1.19, the usage of the specific kubernetes.io/cluster/* resource tags below are required
    # for EKS and Kubernetes to discover and manage networking resources
    # https://www.terraform.io/docs/providers/aws/guides/eks-getting-started.html#base-vpc-networking
    tags = { "kubernetes.io/cluster/${module.label.id}" = "shared" }
  }

  module "vpc" {
    source = "cloudposse/vpc/aws"
    # Cloud Posse recommends pinning every module to a specific version
    # version     = "x.x.x"
    cidr_block = "172.16.0.0/16"

    tags    = local.tags
    context = module.label.context
  }

  module "subnets" {
    source = "cloudposse/dynamic-subnets/aws"
    # Cloud Posse recommends pinning every module to a specific version
    # version     = "x.x.x"

    availability_zones   = var.availability_zones
    vpc_id               = module.vpc.vpc_id
    igw_id               = module.vpc.igw_id
    cidr_block           = module.vpc.vpc_cidr_block
    nat_gateway_enabled  = true
    nat_instance_enabled = false

    tags    = local.tags
    context = module.label.context
  }

  module "eks_node_group" {
    source = "cloudposse/eks-node-group/aws"
    # Cloud Posse recommends pinning every module to a specific version
    # version     = "x.x.x"

    instance_types                     = [var.instance_type]
    subnet_ids                         = module.subnets.public_subnet_ids
    health_check_type                  = var.health_check_type
    min_size                           = var.min_size
    max_size                           = var.max_size
    cluster_name                       = module.eks_cluster.eks_cluster_id

    # Enable the Kubernetes cluster auto-scaler to find the auto-scaling group
    cluster_autoscaler_enabled = var.autoscaling_policies_enabled

    context = module.label.context

    # Ensure the cluster is fully created before trying to add the node group
    module_depends_on = module.eks_cluster.kubernetes_config_map_id
  }

  module "eks_cluster" {
    source = "cloudposse/eks-cluster/aws"
    # Cloud Posse recommends pinning every module to a specific version
    # version     = "x.x.x"

    vpc_id     = module.vpc.vpc_id
    subnet_ids = module.subnets.public_subnet_ids

    kubernetes_version    = var.kubernetes_version
    oidc_provider_enabled = true

    context = module.label.context
  }

Module usage with two worker groups:

locals {
    # Unfortunately, the `aws_ami` data source attribute `most_recent` (https://github.com/cloudposse/terraform-aws-eks-workers/blob/34a43c25624a6efb3ba5d2770a601d7cb3c0d391/main.tf#L141)
    # does not work as you might expect. If you are not going to use a custom AMI you should
    # use the `eks_worker_ami_name_filter` variable to set the right kubernetes version for EKS workers,
    # otherwise the first version of Kubernetes supported by AWS (v1.11) for EKS workers will be selected, but
    # EKS control plane will ignore it to use one that matches the version specified by the `kubernetes_version` variable.
    eks_worker_ami_name_filter = "amazon-eks-node-${var.kubernetes_version}*"
  }

  module "eks_workers" {
    source = "cloudposse/eks-workers/aws"
    # Cloud Posse recommends pinning every module to a specific version
    # version     = "x.x.x"

    attributes                         = ["small"]
    instance_type                      = "t3.small"
    eks_worker_ami_name_filter         = local.eks_worker_ami_name_filter
    vpc_id                             = module.vpc.vpc_id
    subnet_ids                         = module.subnets.public_subnet_ids
    health_check_type                  = var.health_check_type
    min_size                           = var.min_size
    max_size                           = var.max_size
    wait_for_capacity_timeout          = var.wait_for_capacity_timeout
    cluster_name                       = module.label.id
    cluster_endpoint                   = module.eks_cluster.eks_cluster_endpoint
    cluster_certificate_authority_data = module.eks_cluster.eks_cluster_certificate_authority_data
    cluster_security_group_id          = module.eks_cluster.security_group_id

    # Auto-scaling policies and CloudWatch metric alarms
    autoscaling_policies_enabled           = var.autoscaling_policies_enabled
    cpu_utilization_high_threshold_percent = var.cpu_utilization_high_threshold_percent
    cpu_utilization_low_threshold_percent  = var.cpu_utilization_low_threshold_percent

    context = module.label.context
  }

  module "eks_workers_2" {
    source = "cloudposse/eks-workers/aws"
    # Cloud Posse recommends pinning every module to a specific version
    # version     = "x.x.x"

    attributes                         = ["medium"]
    instance_type                      = "t3.medium"
    eks_worker_ami_name_filter         = local.eks_worker_ami_name_filter
    vpc_id                             = module.vpc.vpc_id
    subnet_ids                         = module.subnets.public_subnet_ids
    health_check_type                  = var.health_check_type
    min_size                           = var.min_size
    max_size                           = var.max_size
    wait_for_capacity_timeout          = var.wait_for_capacity_timeout
    cluster_name                       = module.label.id
    cluster_endpoint                   = module.eks_cluster.eks_cluster_endpoint
    cluster_certificate_authority_data = module.eks_cluster.eks_cluster_certificate_authority_data
    cluster_security_group_id          = module.eks_cluster.security_group_id

    # Auto-scaling policies and CloudWatch metric alarms
    autoscaling_policies_enabled           = var.autoscaling_policies_enabled
    cpu_utilization_high_threshold_percent = var.cpu_utilization_high_threshold_percent
    cpu_utilization_low_threshold_percent  = var.cpu_utilization_low_threshold_percent

    context = module.label.context
  }

  module "eks_cluster" {
    source = "cloudposse/eks-cluster/aws"
    # Cloud Posse recommends pinning every module to a specific version
    # version     = "x.x.x"

    vpc_id     = module.vpc.vpc_id
    subnet_ids = module.subnets.public_subnet_ids

    kubernetes_version    = var.kubernetes_version
    oidc_provider_enabled = false

    workers_role_arns          = [module.eks_workers.workers_role_arn, module.eks_workers_2.workers_role_arn]
    workers_security_group_ids = [module.eks_workers.security_group_id, module.eks_workers_2.security_group_id]

    context = module.label.context
  }

Makefile Targets

Available targets:

  help                                Help screen
  help/all                            Display help for all targets
  help/short                          This help short screen
  lint                                Lint terraform code

Requirements

Providers

Modules

Resources

Inputs

list(object({
    addon_name               = string
    addon_version            = string
    resolve_conflicts        = string
    service_account_role_arn = string
  }))

[
  "secrets"
]

{
  "additional_tag_map": {},
  "attributes": [],
  "delimiter": null,
  "descriptor_formats": {},
  "enabled": true,
  "environment": null,
  "id_length_limit": null,
  "label_key_case": null,
  "label_order": [],
  "label_value_case": null,
  "labels_as_tags": [
    "unset"
  ],
  "name": null,
  "namespace": null,
  "regex_replace_chars": null,
  "stage": null,
  "tags": {},
  "tenant": null
}

[
  "default"
]

[
  "/bin/sh",
  "-c"
]

list(object({
    rolearn  = string
    username = string
    groups   = list(string)
  }))

list(object({
    userarn  = string
    username = string
    groups   = list(string)
  }))

[
  "0.0.0.0/0"
]

Outputs

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Related Projects

Check out these related projects.

• terraform-aws-eks-workers - Terraform module to provision an AWS AutoScaling Group, IAM Role, and Security Group for EKS Workers
• terraform-aws-ec2-autoscale-group - Terraform module to provision Auto Scaling Group and Launch Template on AWS
• terraform-aws-ecs-container-definition - Terraform module to generate well-formed JSON documents (container definitions) that are passed to the aws_ecs_task_definition Terraform resource
• terraform-aws-ecs-alb-service-task - Terraform module which implements an ECS service which exposes a web service via ALB
• terraform-aws-ecs-web-app - Terraform module that implements a web app on ECS and supports autoscaling, CI/CD, monitoring, ALB integration, and much more
• terraform-aws-ecs-codepipeline - Terraform module for CI/CD with AWS Code Pipeline and Code Build for ECS
• terraform-aws-ecs-cloudwatch-autoscaling - Terraform module to autoscale ECS Service based on CloudWatch metrics
• terraform-aws-ecs-cloudwatch-sns-alarms - Terraform module to create CloudWatch Alarms on ECS Service level metrics
• terraform-aws-ec2-instance - Terraform module for providing a general purpose EC2 instance
• terraform-aws-ec2-instance-group - Terraform module for provisioning multiple general purpose EC2 hosts for stateful applications

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Bug Reports & Feature Requests

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Copyright

Copyright © 2017-2021 Cloud Posse, LLC

License

See LICENSE for full details.

Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements.  See the NOTICE file
distributed with this work for additional information
regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License.  You may obtain a copy of the License at

  https://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing,
software distributed under the License is distributed on an
"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
KIND, either express or implied.  See the License for the
specific language governing permissions and limitations
under the License.

Trademarks

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Contributors

Erik Osterman	Andriy Knysh	Igor Rodionov	Oscar