terraform/modules/compute_backend/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 {
}

# This block is a replicate from https://github.com/terraform-google-modules/terraform-google-lb-http/blob/v9.0.0/modules/serverless_negs/main.tf
resource "google_compute_backend_service" "default" {
  provider = google-beta
  for_each = var.backends

  project = var.project
  name    = "${var.name}-backend-${each.key}"

  load_balancing_scheme = var.load_balancing_scheme

  port_name = lookup(each.value, "port_name", "http")
  protocol  = lookup(each.value, "protocol", "HTTP")

  description                     = lookup(each.value, "description", null)
  connection_draining_timeout_sec = lookup(each.value, "connection_draining_timeout_sec", null)
  enable_cdn                      = lookup(each.value, "enable_cdn", false)
  compression_mode                = lookup(each.value, "compression_mode", "DISABLED")
  custom_request_headers          = lookup(each.value, "custom_request_headers", [])
  custom_response_headers         = lookup(each.value, "custom_response_headers", [])
  session_affinity                = lookup(each.value, "session_affinity", null)
  affinity_cookie_ttl_sec         = lookup(each.value, "affinity_cookie_ttl_sec", null)


  # # To achieve a null backend edge_security_policy, set each.value.edge_security_policy to "" (empty string), otherwise, it fallsback to var.edge_security_policy.
  # edge_security_policy = lookup(each.value, "edge_security_policy") == "" ? null : (lookup(each.value, "edge_security_policy") == null ? var.edge_security_policy : each.value.edge_security_policy)

  # # To achieve a null backend security_policy, set each.value.security_policy to "" (empty string), otherwise, it fallsback to var.security_policy.
  # security_policy = lookup(each.value, "security_policy") == "" ? null : (lookup(each.value, "security_policy") == null ? var.security_policy : each.value.security_policy)

  dynamic "backend" {
    for_each = toset(each.value["groups"])
    content {
      description = lookup(backend.value, "description", null)
      group       = lookup(backend.value, "group")

    }
  }

  dynamic "log_config" {
    for_each = lookup(lookup(each.value, "log_config", {}), "enable", true) ? [1] : []
    content {
      enable      = lookup(lookup(each.value, "log_config", {}), "enable", true)
      sample_rate = lookup(lookup(each.value, "log_config", {}), "sample_rate", "1.0")
    }
  }

  dynamic "iap" {
    for_each = lookup(lookup(each.value, "iap_config", {}), "enable", false) ? [1] : []
    content {
      oauth2_client_id     = lookup(lookup(each.value, "iap_config", {}), "oauth2_client_id", "")
      oauth2_client_secret = lookup(lookup(each.value, "iap_config", {}), "oauth2_client_secret", "")
    }
  }

  dynamic "cdn_policy" {
    for_each = each.value.enable_cdn ? [1] : []
    content {
      cache_mode                   = each.value.cdn_policy.cache_mode
      signed_url_cache_max_age_sec = each.value.cdn_policy.signed_url_cache_max_age_sec
      default_ttl                  = each.value.cdn_policy.default_ttl
      max_ttl                      = each.value.cdn_policy.max_ttl
      client_ttl                   = each.value.cdn_policy.client_ttl
      negative_caching             = each.value.cdn_policy.negative_caching
      serve_while_stale            = each.value.cdn_policy.serve_while_stale

      dynamic "negative_caching_policy" {
        for_each = each.value.cdn_policy.negative_caching_policy != null ? [1] : []
        content {
          code = each.value.cdn_policy.negative_caching_policy.code
          ttl  = each.value.cdn_policy.negative_caching_policy.ttl
        }
      }

      dynamic "cache_key_policy" {
        for_each = each.value.cdn_policy.cache_key_policy != null ? [1] : []
        content {
          include_host           = each.value.cdn_policy.cache_key_policy.include_host
          include_protocol       = each.value.cdn_policy.cache_key_policy.include_protocol
          include_query_string   = each.value.cdn_policy.cache_key_policy.include_query_string
          query_string_blacklist = each.value.cdn_policy.cache_key_policy.query_string_blacklist
          query_string_whitelist = each.value.cdn_policy.cache_key_policy.query_string_whitelist
          include_http_headers   = each.value.cdn_policy.cache_key_policy.include_http_headers
          include_named_cookies  = each.value.cdn_policy.cache_key_policy.include_named_cookies
        }
      }
    }
  }
}