Better support for KUBECONFIG file authentication (cloudposse/terraform-aws-components#1034)

Author: Nuru

src/README.md

@@ -238,7 +238,8 @@ https-checks:
 | <a name="input_kube_exec_auth_enabled"></a> [kube\_exec\_auth\_enabled](#input\_kube\_exec\_auth\_enabled) | If `true`, use the Kubernetes provider `exec` feature to execute `aws eks get-token` to authenticate to the EKS cluster.<br>Disabled by `kubeconfig_file_enabled`, overrides `kube_data_auth_enabled`. | `bool` | `true` | no |
 | <a name="input_kube_exec_auth_role_arn"></a> [kube\_exec\_auth\_role\_arn](#input\_kube\_exec\_auth\_role\_arn) | The role ARN for `aws eks get-token` to use | `string` | `""` | no |
 | <a name="input_kube_exec_auth_role_arn_enabled"></a> [kube\_exec\_auth\_role\_arn\_enabled](#input\_kube\_exec\_auth\_role\_arn\_enabled) | If `true`, pass `kube_exec_auth_role_arn` as the role ARN to `aws eks get-token` | `bool` | `true` | no |
-| <a name="input_kubeconfig_context"></a> [kubeconfig\_context](#input\_kubeconfig\_context) | Context to choose from the Kubernetes kube config file | `string` | `""` | no |
+| <a name="input_kubeconfig_context"></a> [kubeconfig\_context](#input\_kubeconfig\_context) | Context to choose from the Kubernetes config file.<br>If supplied, `kubeconfig_context_format` will be ignored. | `string` | `""` | no |
+| <a name="input_kubeconfig_context_format"></a> [kubeconfig\_context\_format](#input\_kubeconfig\_context\_format) | A format string to use for creating the `kubectl` context name when<br>`kubeconfig_file_enabled` is `true` and `kubeconfig_context` is not supplied.<br>Must include a single `%s` which will be replaced with the cluster name. | `string` | `""` | no |
 | <a name="input_kubeconfig_exec_auth_api_version"></a> [kubeconfig\_exec\_auth\_api\_version](#input\_kubeconfig\_exec\_auth\_api\_version) | The Kubernetes API version of the credentials returned by the `exec` auth plugin | `string` | `"client.authentication.k8s.io/v1beta1"` | no |
 | <a name="input_kubeconfig_file"></a> [kubeconfig\_file](#input\_kubeconfig\_file) | The Kubernetes provider `config_path` setting to use when `kubeconfig_file_enabled` is `true` | `string` | `""` | no |
 | <a name="input_kubeconfig_file_enabled"></a> [kubeconfig\_file\_enabled](#input\_kubeconfig\_file\_enabled) | If `true`, configure the Kubernetes provider with `kubeconfig_file` and use that kubeconfig file for authenticating to the EKS cluster | `bool` | `false` | no |

src/provider-helm.tf

@@ -21,18 +21,35 @@ variable "kubeconfig_file_enabled" {
   type        = bool
   default     = false
   description = "If `true`, configure the Kubernetes provider with `kubeconfig_file` and use that kubeconfig file for authenticating to the EKS cluster"
+  nullable    = false
 }
 
 variable "kubeconfig_file" {
   type        = string
   default     = ""
   description = "The Kubernetes provider `config_path` setting to use when `kubeconfig_file_enabled` is `true`"
+  nullable    = false
 }
 
 variable "kubeconfig_context" {
   type        = string
   default     = ""
-  description = "Context to choose from the Kubernetes kube config file"
+  description = <<-EOT
+    Context to choose from the Kubernetes config file.
+    If supplied, `kubeconfig_context_format` will be ignored.
+    EOT
+  nullable    = false
+}
+
+variable "kubeconfig_context_format" {
+  type        = string
+  default     = ""
+  description = <<-EOT
+    A format string to use for creating the `kubectl` context name when
+    `kubeconfig_file_enabled` is `true` and `kubeconfig_context` is not supplied.
+    Must include a single `%s` which will be replaced with the cluster name.
+    EOT
+  nullable    = false
 }
 
 variable "kube_data_auth_enabled" {
@@ -42,6 +59,7 @@ variable "kube_data_auth_enabled" {
     If `true`, use an `aws_eks_cluster_auth` data source to authenticate to the EKS cluster.
     Disabled by `kubeconfig_file_enabled` or `kube_exec_auth_enabled`.
     EOT
+  nullable    = false
 }
 
 variable "kube_exec_auth_enabled" {
@@ -51,48 +69,62 @@ variable "kube_exec_auth_enabled" {
     If `true`, use the Kubernetes provider `exec` feature to execute `aws eks get-token` to authenticate to the EKS cluster.
     Disabled by `kubeconfig_file_enabled`, overrides `kube_data_auth_enabled`.
     EOT
+  nullable    = false
 }
 
 variable "kube_exec_auth_role_arn" {
   type        = string
   default     = ""
   description = "The role ARN for `aws eks get-token` to use"
+  nullable    = false
 }
 
 variable "kube_exec_auth_role_arn_enabled" {
   type        = bool
   default     = true
   description = "If `true`, pass `kube_exec_auth_role_arn` as the role ARN to `aws eks get-token`"
+  nullable    = false
 }
 
 variable "kube_exec_auth_aws_profile" {
   type        = string
   default     = ""
   description = "The AWS config profile for `aws eks get-token` to use"
+  nullable    = false
 }
 
 variable "kube_exec_auth_aws_profile_enabled" {
   type        = bool
   default     = false
   description = "If `true`, pass `kube_exec_auth_aws_profile` as the `profile` to `aws eks get-token`"
+  nullable    = false
 }
 
 variable "kubeconfig_exec_auth_api_version" {
   type        = string
   default     = "client.authentication.k8s.io/v1beta1"
   description = "The Kubernetes API version of the credentials returned by the `exec` auth plugin"
+  nullable    = false
 }
 
 variable "helm_manifest_experiment_enabled" {
   type        = bool
   default     = false
   description = "Enable storing of the rendered manifest for helm_release so the full diff of what is changing can been seen in the plan"
+  nullable    = false
 }
 
 locals {
   kubeconfig_file_enabled = var.kubeconfig_file_enabled
-  kube_exec_auth_enabled  = local.kubeconfig_file_enabled ? false : var.kube_exec_auth_enabled
-  kube_data_auth_enabled  = local.kube_exec_auth_enabled ? false : var.kube_data_auth_enabled
+  kubeconfig_file         = local.kubeconfig_file_enabled ? var.kubeconfig_file : ""
+  kubeconfig_context = !local.kubeconfig_file_enabled ? "" : (
+    length(var.kubeconfig_context) != 0 ? var.kubeconfig_context : (
+      length(var.kubeconfig_context_format) != 0 ? format(var.kubeconfig_context_format, local.eks_cluster_id) : ""
+    )
+  )
+
+  kube_exec_auth_enabled = local.kubeconfig_file_enabled ? false : var.kube_exec_auth_enabled
+  kube_data_auth_enabled = local.kube_exec_auth_enabled ? false : var.kube_data_auth_enabled
 
   # Eventually we might try to get this from an environment variable
   kubeconfig_exec_auth_api_version = var.kubeconfig_exec_auth_api_version
@@ -107,10 +139,11 @@ locals {
   ] : []
 
   # Provide dummy configuration for the case where the EKS cluster is not available.
-  certificate_authority_data = try(module.eks.outputs.eks_cluster_certificate_authority_data, "")
+  certificate_authority_data = local.kubeconfig_file_enabled ? null : try(module.eks.outputs.eks_cluster_certificate_authority_data, null)
+  cluster_ca_certificate     = local.kubeconfig_file_enabled ? null : try(base64decode(local.certificate_authority_data), null)
   # Use coalesce+try to handle both the case where the output is missing and the case where it is empty.
   eks_cluster_id       = coalesce(try(module.eks.outputs.eks_cluster_id, ""), "missing")
-  eks_cluster_endpoint = try(module.eks.outputs.eks_cluster_endpoint, "")
+  eks_cluster_endpoint = local.kubeconfig_file_enabled ? null : try(module.eks.outputs.eks_cluster_endpoint, "")
 }
 
 data "aws_eks_cluster_auth" "eks" {
@@ -121,15 +154,16 @@ data "aws_eks_cluster_auth" "eks" {
 provider "helm" {
   kubernetes {
     host                   = local.eks_cluster_endpoint
-    cluster_ca_certificate = base64decode(local.certificate_authority_data)
+    cluster_ca_certificate = local.cluster_ca_certificate
     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_file_enabled ? var.kubeconfig_file : ""
-    config_context = var.kubeconfig_context
+    # It is too confusing to allow the Kubernetes provider to use environment variables to set authentication
+    # in this module because we have so many options, so we override environment variables like `KUBE_CONFIG_PATH`
+    # in all cases. People can still use environment variables by setting TF_VAR_kubeconfig_file.
+    config_path    = local.kubeconfig_file
+    config_context = local.kubeconfig_context
 
     dynamic "exec" {
-      for_each = local.kube_exec_auth_enabled && length(local.certificate_authority_data) > 0 ? ["exec"] : []
+      for_each = local.kube_exec_auth_enabled && local.certificate_authority_data != null ? ["exec"] : []
       content {
         api_version = local.kubeconfig_exec_auth_api_version
         command     = "aws"
@@ -146,15 +180,16 @@ provider "helm" {
 
 provider "kubernetes" {
   host                   = local.eks_cluster_endpoint
-  cluster_ca_certificate = base64decode(local.certificate_authority_data)
+  cluster_ca_certificate = local.cluster_ca_certificate
   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_file_enabled ? var.kubeconfig_file : ""
-  config_context = var.kubeconfig_context
+  # It is too confusing to allow the Kubernetes provider to use environment variables to set authentication
+  # in this module because we have so many options, so we override environment variables like `KUBE_CONFIG_PATH`
+  # in all cases. People can still use environment variables by setting TF_VAR_kubeconfig_file.
+  config_path    = local.kubeconfig_file
+  config_context = local.kubeconfig_context
 
   dynamic "exec" {
-    for_each = local.kube_exec_auth_enabled && length(local.certificate_authority_data) > 0 ? ["exec"] : []
+    for_each = local.kube_exec_auth_enabled && local.certificate_authority_data != null ? ["exec"] : []
     content {
       api_version = local.kubeconfig_exec_auth_api_version
       command     = "aws"