modules/tfc-oidc/main.tf

/**
 * Copyright 2023 Google LLC
 *
 * Licensed 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
 *
 *      http://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.
 */

locals {
  attribute_condition = var.attribute_condition == "" ? "assertion.sub.startsWith(\"organization:${var.tfc_organization_name}:project:${var.tfc_project_name}:workspace:${var.tfc_workspace_name}\")" : var.attribute_condition
}

# Enables the required services in the project.
# https://registry.terraform.io/providers/hashicorp/google/latest/docs/resources/google_project_service
resource "google_project_service" "services" {
  project            = var.project_id
  count              = length(var.service_list)
  service            = var.service_list[count.index]
  disable_on_destroy = false
}

# Creates a workload identity pool to house a workload identity pool provider.
# https://registry.terraform.io/providers/hashicorp/google/latest/docs/resources/iam_workload_identity_pool
resource "google_iam_workload_identity_pool" "tfc_pool" {
  project                   = var.project_id
  workload_identity_pool_id = var.pool_id
  display_name              = var.pool_display_name
  description               = var.pool_description
  disabled                  = false
}

# Creates an identity pool provider which uses an attribute condition
# to ensure that only the specified Terraform Cloud workspace will be
# able to authenticate to GCP using this provider.
# https://registry.terraform.io/providers/hashicorp/google/latest/docs/resources/iam_workload_identity_pool_provider
resource "google_iam_workload_identity_pool_provider" "tfc_provider" {
  project                            = var.project_id
  workload_identity_pool_id          = google_iam_workload_identity_pool.tfc_pool.workload_identity_pool_id
  workload_identity_pool_provider_id = var.provider_id
  display_name                       = var.provider_display_name
  description                        = var.provider_description
  attribute_mapping                  = var.attribute_mapping
  attribute_condition                = local.attribute_condition
  oidc {
    issuer_uri        = var.issuer_uri
    allowed_audiences = var.allowed_audiences
  }
}

# Allows the service account to act as a workload identity user.
# https://registry.terraform.io/providers/hashicorp/google/latest/docs/resources/google_service_account_iam
resource "google_service_account_iam_member" "tfc_service_account_member" {
  for_each           = var.sa_mapping
  service_account_id = each.value.sa_name
  role               = "roles/iam.workloadIdentityUser"
  member             = "principalSet://iam.googleapis.com/${google_iam_workload_identity_pool.tfc_pool.name}/${each.value.attribute}"
}