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fix: Enhance WI module usability with existing KSA (#557)
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-10
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+111
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‎examples/workload_identity/main.tf

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@@ -53,6 +53,7 @@ module "gke" {
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]
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}
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# example without existing KSA
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module "workload_identity" {
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source = "../../modules/workload-identity"
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project_id = var.project_id
@@ -61,5 +62,27 @@ module "workload_identity" {
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use_existing_k8s_sa = false
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}
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# example with existing KSA
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resource "kubernetes_service_account" "test" {
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metadata {
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name = "foo-ksa"
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}
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secret {
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name = "bar"
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}
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}
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module "workload_identity_existing_ksa" {
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source = "../../modules/workload-identity"
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project_id = var.project_id
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name = "existing-${module.gke.name}"
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cluster_name = module.gke.name
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location = module.gke.location
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namespace = "default"
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use_existing_k8s_sa = true
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k8s_sa_name = kubernetes_service_account.test.metadata.0.name
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}
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data "google_client_config" "default" {
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}

‎modules/workload-identity/README.md

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@@ -51,9 +51,6 @@ resource "kubernetes_service_account" "preexisting" {
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metadata {
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name = "preexisting-sa"
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namespace = "prod"
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annotations = {
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"iam.gke.io/gcp-service-account" = "preexisting-sa@${var.project_id}.iam.gserviceaccount.com"
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}
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}
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}
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@@ -71,7 +68,9 @@ module "my-app-workload-identity" {
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| Name | Description | Type | Default | Required |
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|------|-------------|:----:|:-----:|:-----:|
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| cluster\_name | Cluster name. Required if using existing KSA. | string | `""` | no |
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| k8s\_sa\_name | Name for the existing Kubernetes service account | string | `"null"` | no |
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| location | Cluster location (region if regional cluster, zone if zonal cluster). Required if using existing KSA. | string | `""` | no |
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| name | Name for both service accounts | string | n/a | yes |
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| namespace | Namespace for k8s service account | string | `"default"` | no |
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| project\_id | GCP project ID | string | n/a | yes |

‎modules/workload-identity/main.tf

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Original file line numberDiff line numberDiff line change
@@ -19,9 +19,23 @@ locals {
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gcp_sa_email = google_service_account.cluster_service_account.email
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# This will cause terraform to block returning outputs until the service account is created
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k8s_given_name = var.k8s_sa_name != null ? var.k8s_sa_name : var.name
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output_k8s_name = var.use_existing_k8s_sa ? local.k8s_given_name : kubernetes_service_account.main[0].metadata[0].name
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output_k8s_namespace = var.use_existing_k8s_sa ? var.namespace : kubernetes_service_account.main[0].metadata[0].namespace
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k8s_given_name = var.k8s_sa_name != null ? var.k8s_sa_name : var.name
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output_k8s_name = var.use_existing_k8s_sa ? local.k8s_given_name : kubernetes_service_account.main[0].metadata[0].name
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output_k8s_namespace = var.use_existing_k8s_sa ? var.namespace : kubernetes_service_account.main[0].metadata[0].namespace
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token = var.use_existing_k8s_sa ? data.google_client_config.default.0.access_token : ""
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cluster_ca_certificate = var.use_existing_k8s_sa ? data.google_container_cluster.primary.0.master_auth.0.cluster_ca_certificate : ""
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cluster_endpoint = var.use_existing_k8s_sa ? "https://${data.google_container_cluster.primary.0.endpoint}" : ""
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}
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data "google_container_cluster" "primary" {
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count = var.use_existing_k8s_sa ? 1 : 0
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name = var.cluster_name
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project = var.project_id
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location = var.location
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}
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data "google_client_config" "default" {
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count = var.use_existing_k8s_sa ? 1 : 0
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}
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resource "google_service_account" "cluster_service_account" {
@@ -51,11 +65,11 @@ module "annotate-sa" {
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enabled = var.use_existing_k8s_sa
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skip_download = true
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create_cmd_entrypoint = "kubectl"
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create_cmd_body = "annotate sa -n ${local.output_k8s_namespace} ${local.k8s_given_name} iam.gke.io/gcp-service-account=${local.gcp_sa_email}"
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create_cmd_entrypoint = "${path.module}/scripts/kubectl_wrapper.sh"
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create_cmd_body = "${local.cluster_endpoint} ${local.token} ${local.cluster_ca_certificate} kubectl annotate --overwrite sa -n ${local.output_k8s_namespace} ${local.k8s_given_name} iam.gke.io/gcp-service-account=${local.gcp_sa_email}"
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destroy_cmd_entrypoint = "kubectl"
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destroy_cmd_body = "annotate sa -n ${local.output_k8s_namespace} ${local.k8s_given_name} iam.gke.io/gcp-service-account-"
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destroy_cmd_entrypoint = "${path.module}/scripts/kubectl_wrapper.sh"
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destroy_cmd_body = "${local.cluster_endpoint} ${local.token} ${local.cluster_ca_certificate} kubectl annotate sa -n ${local.output_k8s_namespace} ${local.k8s_given_name} iam.gke.io/gcp-service-account-"
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}
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resource "google_service_account_iam_member" "main" {

‎modules/workload-identity/scripts/kubectl_wrapper.sh

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@@ -0,0 +1,53 @@
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#!/bin/bash
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# Copyright 2018 Google LLC
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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set -e
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if [ "$#" -lt 3 ]; then
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>&2 echo "Not all expected arguments set."
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exit 1
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fi
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HOST=$1
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TOKEN=$2
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CA_CERTIFICATE=$3
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shift 3
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RANDOM_ID="${RANDOM}_${RANDOM}"
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export TMPDIR="/tmp/kubectl_wrapper_${RANDOM_ID}"
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function cleanup {
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rm -rf "${TMPDIR}"
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}
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trap cleanup EXIT
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mkdir "${TMPDIR}"
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export KUBECONFIG="${TMPDIR}/config"
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# shellcheck disable=SC1117
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base64 --help | grep "\--decode" && B64_ARG="--decode" || B64_ARG="-d"
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echo "${CA_CERTIFICATE}" | base64 ${B64_ARG} > "${TMPDIR}/ca_certificate"
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kubectl config set-cluster kubectl-wrapper --server="${HOST}" --certificate-authority="${TMPDIR}/ca_certificate" --embed-certs=true 1>/dev/null
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rm -f "${TMPDIR}/ca_certificate"
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kubectl config set-context kubectl-wrapper --cluster=kubectl-wrapper --user=kubectl-wrapper --namespace=default 1>/dev/null
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kubectl config set-credentials kubectl-wrapper --token="${TOKEN}" 1>/dev/null
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kubectl config use-context kubectl-wrapper 1>/dev/null
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kubectl version 1>/dev/null
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"$@"

‎modules/workload-identity/variables.tf

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Original file line numberDiff line numberDiff line change
@@ -19,6 +19,18 @@ variable "name" {
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type = string
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}
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variable "cluster_name" {
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description = "Cluster name. Required if using existing KSA."
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type = string
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default = ""
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}
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variable "location" {
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description = "Cluster location (region if regional cluster, zone if zonal cluster). Required if using existing KSA."
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type = string
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default = ""
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}
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variable "k8s_sa_name" {
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description = "Name for the existing Kubernetes service account"
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type = string

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