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Use AWS API for EKS authentication and authorization (cloudposse#206)
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# The EKS service does not provide a cluster-level API parameter or resource to automatically configure the underlying Kubernetes cluster | ||
# to allow worker nodes to join the cluster via AWS IAM role authentication. | ||
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# NOTE: To automatically apply the Kubernetes configuration to the cluster (which allows the worker nodes to join the cluster), | ||
# the requirements outlined here must be met: | ||
# https://learn.hashicorp.com/terraform/aws/eks-intro#preparation | ||
# https://learn.hashicorp.com/terraform/aws/eks-intro#configuring-kubectl-for-eks | ||
# https://learn.hashicorp.com/terraform/aws/eks-intro#required-kubernetes-configuration-to-join-worker-nodes | ||
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# Additional links | ||
# https://learn.hashicorp.com/terraform/aws/eks-intro | ||
# https://itnext.io/how-does-client-authentication-work-on-amazon-eks-c4f2b90d943b | ||
# https://docs.aws.amazon.com/eks/latest/userguide/create-kubeconfig.html | ||
# https://docs.aws.amazon.com/eks/latest/userguide/add-user-role.html | ||
# https://docs.aws.amazon.com/cli/latest/reference/eks/update-kubeconfig.html | ||
# https://docs.aws.amazon.com/en_pv/eks/latest/userguide/create-kubeconfig.html | ||
# https://itnext.io/kubernetes-authorization-via-open-policy-agent-a9455d9d5ceb | ||
# http://marcinkaszynski.com/2018/07/12/eks-auth.html | ||
# https://cloud.google.com/kubernetes-engine/docs/concepts/configmap | ||
# http://yaml-multiline.info | ||
# https://github.com/terraform-providers/terraform-provider-kubernetes/issues/216 | ||
# https://www.terraform.io/docs/cloud/run/install-software.html | ||
# https://stackoverflow.com/questions/26123740/is-it-possible-to-install-aws-cli-package-without-root-permission | ||
# https://stackoverflow.com/questions/58232731/kubectl-missing-form-terraform-cloud | ||
# https://docs.aws.amazon.com/cli/latest/userguide/install-bundle.html | ||
# https://docs.aws.amazon.com/cli/latest/userguide/install-cliv1.html | ||
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locals { | ||
yaml_quote = var.aws_auth_yaml_strip_quotes ? "" : "\"" | ||
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need_kubernetes_provider = local.enabled && var.apply_config_map_aws_auth | ||
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kubeconfig_path_enabled = local.need_kubernetes_provider && var.kubeconfig_path_enabled | ||
kube_exec_auth_enabled = local.kubeconfig_path_enabled ? false : local.need_kubernetes_provider && var.kube_exec_auth_enabled | ||
kube_data_auth_enabled = local.kube_exec_auth_enabled ? false : local.need_kubernetes_provider && var.kube_data_auth_enabled | ||
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exec_profile = local.kube_exec_auth_enabled && var.kube_exec_auth_aws_profile_enabled ? ["--profile", var.kube_exec_auth_aws_profile] : [] | ||
exec_role = local.kube_exec_auth_enabled && var.kube_exec_auth_role_arn_enabled ? ["--role-arn", var.kube_exec_auth_role_arn] : [] | ||
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cluster_endpoint_data = join("", aws_eks_cluster.default[*].endpoint) # use `join` instead of `one` to keep the value a string | ||
cluster_auth_map_endpoint = var.apply_config_map_aws_auth ? local.cluster_endpoint_data : var.dummy_kubeapi_server | ||
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certificate_authority_data_list = coalescelist(aws_eks_cluster.default[*].certificate_authority, [[{ data : "" }]]) | ||
certificate_authority_data_list_internal = local.certificate_authority_data_list[0] | ||
certificate_authority_data_map = local.certificate_authority_data_list_internal[0] | ||
certificate_authority_data = local.certificate_authority_data_map["data"] | ||
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# Add worker nodes role ARNs (could be from many un-managed worker groups) to the ConfigMap | ||
# Note that we don't need to do this for managed Node Groups since EKS adds their roles to the ConfigMap automatically | ||
map_worker_roles = [ | ||
for role_arn in var.workers_role_arns : { | ||
rolearn = role_arn | ||
username = "system:node:{{EC2PrivateDNSName}}" | ||
groups = [ | ||
"system:bootstrappers", | ||
"system:nodes" | ||
] | ||
} | ||
] | ||
} | ||
# Extract the cluster certificate for use in OIDC configuration | ||
certificate_authority_data = try(aws_eks_cluster.default[0].certificate_authority[0]["data"], "") | ||
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eks_policy_short_abbreviation_map = { | ||
# List available policies with `aws eks list-access-policies --output table` | ||
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Admin = "arn:aws:eks::aws:cluster-access-policy/AmazonEKSAdminPolicy" | ||
ClusterAdmin = "arn:aws:eks::aws:cluster-access-policy/AmazonEKSClusterAdminPolicy" | ||
Edit = "arn:aws:eks::aws:cluster-access-policy/AmazonEKSEditPolicy" | ||
View = "arn:aws:eks::aws:cluster-access-policy/AmazonEKSViewPolicy" | ||
# Add new policies here | ||
} | ||
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eks_policy_abbreviation_map = merge({ for k, v in local.eks_policy_short_abbreviation_map : format("AmazonEKS%sPolicy", k) => v }, | ||
local.eks_policy_short_abbreviation_map) | ||
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resource "null_resource" "wait_for_cluster" { | ||
count = local.enabled && var.apply_config_map_aws_auth ? 1 : 0 | ||
depends_on = [ | ||
aws_eks_cluster.default, | ||
aws_security_group_rule.custom_ingress_rules, | ||
aws_security_group_rule.managed_ingress_security_groups, | ||
aws_security_group_rule.managed_ingress_cidr_blocks, | ||
] | ||
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provisioner "local-exec" { | ||
command = var.wait_for_cluster_command | ||
interpreter = var.local_exec_interpreter | ||
environment = { | ||
ENDPOINT = local.cluster_endpoint_data | ||
} | ||
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# Expand abbreviated access policies to full ARNs | ||
access_entry_expanded_map = { for k, v in var.access_entry_map : k => merge({ | ||
# Expand abbreviated policies to full ARNs | ||
access_policy_associations = { for kk, vv in v.access_policy_associations : try(local.eks_policy_abbreviation_map[kk], kk) => vv } | ||
# Copy over all other fields | ||
}, { for kk, vv in v : kk => vv if kk != "access_policy_associations" }) | ||
} | ||
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# Replace membership in "system:masters" group with association to "ClusterAdmin" policy | ||
access_entry_map = { for k, v in local.access_entry_expanded_map : k => merge({ | ||
# Remove "system:masters" group from standard users | ||
kubernetes_groups = [for group in v.kubernetes_groups : group if group != "system:masters" || v.type != "STANDARD"] | ||
access_policy_associations = merge( | ||
# copy all existing associations | ||
v.access_policy_associations, | ||
# add "ClusterAdmin" policy if the user was in "system:masters" group and is a standard user | ||
contains(v.kubernetes_groups, "system:masters") && v.type == "STANDARD" ? { | ||
"arn:aws:eks::aws:cluster-access-policy/AmazonEKSClusterAdminPolicy" = { | ||
access_scope = { | ||
type = "cluster" | ||
namespaces = null | ||
} | ||
} | ||
} : {} | ||
) | ||
# Copy over all other fields | ||
}, { for kk, vv in v : kk => vv if kk != "kubernetes_groups" && kk != "access_policy_associations" }) | ||
} | ||
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eks_access_policy_association_product_map = merge(flatten([ | ||
for k, v in local.access_entry_map : [for kk, vv in v.access_policy_associations : { format("%s-%s", k, kk) = { | ||
principal_arn = k | ||
policy_arn = kk | ||
} | ||
}] | ||
])...) | ||
} | ||
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# The preferred way to keep track of entries is by key, but we also support list, | ||
# because keys need to be known at plan time, but list values do not. | ||
resource "aws_eks_access_entry" "map" { | ||
for_each = local.enabled ? local.access_entry_map : {} | ||
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cluster_name = local.eks_cluster_id | ||
principal_arn = each.key | ||
kubernetes_groups = each.value.kubernetes_groups | ||
type = each.value.type | ||
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# Get an authentication token to communicate with the EKS cluster. | ||
# By default (before other roles are added to the Auth ConfigMap), you can authenticate to EKS cluster only by assuming the role that created the cluster. | ||
# `aws_eks_cluster_auth` uses IAM credentials from the AWS provider to generate a temporary token. | ||
# If the AWS provider assumes an IAM role, `aws_eks_cluster_auth` will use the same IAM role to get the auth token. | ||
# https://www.terraform.io/docs/providers/aws/d/eks_cluster_auth.html | ||
# | ||
# You can set `kube_exec_auth_enabled` to use a different IAM Role or AWS config profile to fetch the auth token | ||
# | ||
data "aws_eks_cluster_auth" "eks" { | ||
count = local.kube_data_auth_enabled ? 1 : 0 | ||
name = one(aws_eks_cluster.default[*].id) | ||
tags = module.this.tags | ||
} | ||
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resource "aws_eks_access_policy_association" "map" { | ||
for_each = local.enabled ? local.eks_access_policy_association_product_map : {} | ||
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cluster_name = local.eks_cluster_id | ||
principal_arn = each.value.principal_arn | ||
policy_arn = each.value.policy_arn | ||
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provider "kubernetes" { | ||
# Without a dummy API server configured, the provider will throw an error and prevent a "plan" from succeeding | ||
# in situations where Terraform does not provide it with the cluster endpoint before triggering an API call. | ||
# Since those situations are limited to ones where we do not care about the failure, such as fetching the | ||
# ConfigMap before the cluster has been created or in preparation for deleting it, and the worst that will | ||
# happen is that the aws-auth ConfigMap will be unnecessarily updated, it is just better to ignore the error | ||
# so we can proceed with the task of creating or destroying the cluster. | ||
# | ||
# If this solution bothers you, you can disable it by setting var.dummy_kubeapi_server = null | ||
host = local.cluster_auth_map_endpoint | ||
cluster_ca_certificate = local.enabled && !local.kubeconfig_path_enabled ? base64decode(local.certificate_authority_data) : null | ||
token = local.kube_data_auth_enabled ? one(data.aws_eks_cluster_auth.eks[*].token) : null | ||
# The Kubernetes provider will use information from KUBECONFIG if it exists, but if the default cluster | ||
# in KUBECONFIG is some other cluster, this will cause problems, so we override it always. | ||
config_path = local.kubeconfig_path_enabled ? var.kubeconfig_path : "" | ||
config_context = var.kubeconfig_context | ||
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dynamic "exec" { | ||
for_each = local.kube_exec_auth_enabled && length(local.cluster_endpoint_data) > 0 ? ["exec"] : [] | ||
content { | ||
api_version = "client.authentication.k8s.io/v1beta1" | ||
command = "aws" | ||
args = concat(local.exec_profile, ["eks", "get-token", "--cluster-name", try(aws_eks_cluster.default[0].id, "deleted")], local.exec_role) | ||
} | ||
access_scope { | ||
type = local.access_entry_map[each.value.principal_arn].access_policy_associations[each.value.policy_arn].access_scope.type | ||
namespaces = local.access_entry_map[each.value.principal_arn].access_policy_associations[each.value.policy_arn].access_scope.namespaces | ||
} | ||
} | ||
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resource "kubernetes_config_map" "aws_auth_ignore_changes" { | ||
count = local.enabled && var.apply_config_map_aws_auth && var.kubernetes_config_map_ignore_role_changes ? 1 : 0 | ||
depends_on = [null_resource.wait_for_cluster] | ||
# We could combine all the list access entries into a single resource, | ||
# but separating them by category minimizes the ripple effect of changes | ||
# due to adding and removing items from the list. | ||
resource "aws_eks_access_entry" "standard" { | ||
count = local.enabled ? length(var.access_entries) : 0 | ||
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metadata { | ||
name = "aws-auth" | ||
namespace = "kube-system" | ||
} | ||
cluster_name = local.eks_cluster_id | ||
principal_arn = var.access_entries[count.index].principal_arn | ||
kubernetes_groups = var.access_entries[count.index].kubernetes_groups | ||
type = "STANDARD" | ||
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data = { | ||
mapRoles = yamlencode(distinct(concat(local.map_worker_roles, var.map_additional_iam_roles))) | ||
mapUsers = yamlencode(var.map_additional_iam_users) | ||
mapAccounts = yamlencode(var.map_additional_aws_accounts) | ||
} | ||
tags = module.this.tags | ||
} | ||
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lifecycle { | ||
ignore_changes = [data["mapRoles"]] | ||
} | ||
resource "aws_eks_access_entry" "linux" { | ||
count = local.enabled ? length(lookup(var.access_entries_for_nodes, "EC2_LINUX", [])) : 0 | ||
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cluster_name = local.eks_cluster_id | ||
principal_arn = var.access_entries_for_nodes.EC2_LINUX[count.index] | ||
type = "EC2_LINUX" | ||
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tags = module.this.tags | ||
} | ||
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resource "kubernetes_config_map" "aws_auth" { | ||
count = local.enabled && var.apply_config_map_aws_auth && var.kubernetes_config_map_ignore_role_changes == false ? 1 : 0 | ||
depends_on = [null_resource.wait_for_cluster] | ||
resource "aws_eks_access_entry" "windows" { | ||
count = local.enabled ? length(lookup(var.access_entries_for_nodes, "EC2_WINDOWS", [])) : 0 | ||
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metadata { | ||
name = "aws-auth" | ||
namespace = "kube-system" | ||
} | ||
cluster_name = local.eks_cluster_id | ||
principal_arn = var.access_entries_for_nodes.EC2_WINDOWS[count.index] | ||
type = "EC2_WINDOWS" | ||
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tags = module.this.tags | ||
} | ||
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resource "aws_eks_access_policy_association" "list" { | ||
count = local.enabled ? length(var.access_policy_associations) : 0 | ||
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cluster_name = local.eks_cluster_id | ||
principal_arn = var.access_policy_associations[count.index].principal_arn | ||
policy_arn = try(local.eks_policy_abbreviation_map[var.access_policy_associations[count.index].policy_arn], | ||
var.access_policy_associations[count.index].policy_arn) | ||
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data = { | ||
mapRoles = replace(yamlencode(distinct(concat(local.map_worker_roles, var.map_additional_iam_roles))), "\"", local.yaml_quote) | ||
mapUsers = replace(yamlencode(var.map_additional_iam_users), "\"", local.yaml_quote) | ||
mapAccounts = replace(yamlencode(var.map_additional_aws_accounts), "\"", local.yaml_quote) | ||
access_scope { | ||
type = var.access_policy_associations[count.index].access_scope.type | ||
namespaces = var.access_policy_associations[count.index].access_scope.namespaces | ||
} | ||
} |
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