feat(google_fastly_waf): add ddos notification for slack

google_fastly_waf/README.md

@@ -148,8 +148,10 @@ module "fastly_stage" {
 | <a name="input_cache_settings"></a> [cache\_settings](#input\_cache\_settings) | List of cache settings for the Fastly service. | <pre>list(object({<br/>    name            = string<br/>    action          = optional(string)<br/>    cache_condition = optional(string)<br/>    stale_ttl       = optional(number)<br/>    ttl             = optional(number)<br/>  }))</pre> | `[]` | no |
 | <a name="input_conditions"></a> [conditions](#input\_conditions) | List of Fastly conditions to create (REQUEST, RESPONSE or CACHE). | <pre>list(object({<br/>    name      = string           # required, unique<br/>    statement = string           # VCL conditional expression<br/>    type      = string           # one of: REQUEST, RESPONSE, CACHE<br/>    priority  = optional(number) # lower runs first, default 10<br/>  }))</pre> | `[]` | no |
 | <a name="input_ddos_protection"></a> [ddos\_protection](#input\_ddos\_protection) | Optional DDoS Protection configuration for the Fastly service product enablement. | <pre>object({<br/>    enabled = bool<br/>    mode    = string<br/>  })</pre> | `null` | no |
+| <a name="input_ddos_protection_alert"></a> [ddos\_protection\_alert](#input\_ddos\_protection\_alert) | Optional Slack alerting for Fastly DDoS Protection. When set, the module creates a Slack `fastly_integration` and a `fastly_alert` on the `ddos_protection_requests_detect_count` stats metric that notifies the channel behind the webhook. Intended to be paired with `ddos_protection` being enabled. Set to `null` (the default) to create no alerting resources. | <pre>object({<br/>    enabled              = optional(bool, true)<br/>    slack_webhook_secret = string<br/>    threshold            = optional(number, 1)<br/>    period               = optional(string, "5m")<br/>  })</pre> | `null` | no |
 | <a name="input_domains"></a> [domains](#input\_domains) | A list of domains | `list(any)` | `[]` | no |
 | <a name="input_https_redirect_enabled"></a> [https\_redirect\_enabled](#input\_https\_redirect\_enabled) | n/a | `bool` | `true` | no |
+| <a name="input_legacy_edge_deployment"></a> [legacy\_edge\_deployment](#input\_legacy\_edge\_deployment) | If true (default), deploy NGWAF via the legacy sigsci EdgeDeployment APIs and Fastly dynamic snippets. If false, deploy via Fastly's product\_enablement ngwaf block. Default preserves behavior for services still on the legacy method. | `bool` | `true` | no |
 | <a name="input_log_sampling_enabled"></a> [log\_sampling\_enabled](#input\_log\_sampling\_enabled) | n/a | `bool` | `false` | no |
 | <a name="input_log_sampling_percent"></a> [log\_sampling\_percent](#input\_log\_sampling\_percent) | n/a | `string` | `"10"` | no |
 | <a name="input_ngwaf_agent_level"></a> [ngwaf\_agent\_level](#input\_ngwaf\_agent\_level) | This is the site wide blocking level | `string` | `"log"` | no |

google_fastly_waf/alerts.tf

@@ -0,0 +1,40 @@
+# DDoS Protection alerting
+# When var.ddos_protection_alert is set, create a Slack integration and a
+# Fastly stats alert that fires on the `ddos_protection_requests_detect_count`
+# metric (requests classified as DDoS attacks). This is only meaningful when
+# ddos_protection is enabled (mode "log" or "block").
+
+locals {
+  ddos_protection_alert_enabled = (
+    var.ddos_protection_alert != null && var.ddos_protection_alert.enabled
+  )
+}
+
+resource "fastly_integration" "ddos_protection_slack" {
+  count = local.ddos_protection_alert_enabled ? 1 : 0
+
+  name        = "${var.application}-${var.realm}-${var.environment} DDoS Protection Slack integration"
+  description = "Slack notifications for Fastly DDoS Protection detection events"
+  type        = "slack"
+
+  config = {
+    webhook = sensitive(var.ddos_protection_alert.slack_webhook_secret)
+  }
+}
+
+resource "fastly_alert" "ddos_protection" {
+  count = local.ddos_protection_alert_enabled ? 1 : 0
+
+  name       = "${var.application}-${var.realm}-${var.environment} DDoS Protection events"
+  service_id = fastly_service_vcl.default.id
+  source     = "stats"
+  metric     = "ddos_protection_requests_detect_count"
+
+  evaluation_strategy {
+    type      = "above_threshold"
+    period    = var.ddos_protection_alert.period
+    threshold = var.ddos_protection_alert.threshold
+  }
+
+  integration_ids = [fastly_integration.ddos_protection_slack[0].id]
+}

google_fastly_waf/variables.tf

@@ -143,6 +143,41 @@ variable "ddos_protection" {
   }
 }
 
+variable "ddos_protection_alert" {
+  description = <<-EOT
+    Optional Slack alerting for Fastly DDoS Protection. When set, the module
+    creates a Slack `fastly_integration` and a `fastly_alert` on the
+    `ddos_protection_requests_detect_count` stats metric that notifies the
+    channel behind the webhook. Intended to be paired with `ddos_protection`
+    being enabled.
+    Set to `null` (the default) to create no alerting resources.
+  EOT
+  type = object({
+    enabled              = optional(bool, true)   # set false to keep config but tear the alert down
+    slack_webhook_secret = string                 # Slack incoming-webhook URL (sensitive)
+    threshold            = optional(number, 1)    # ddos_protection_requests_detect_count that fires the alert
+    period               = optional(string, "5m") # evaluation window: 2m, 3m, 5m, 15m, or 30m
+  })
+  default = null
+  validation {
+    condition = var.ddos_protection_alert == null || contains(
+      ["2m", "3m", "5m", "15m", "30m"], var.ddos_protection_alert.period
+    )
+    error_message = "ddos_protection_alert.period must be one of: 2m, 3m, 5m, 15m, or 30m."
+  }
+  validation {
+    # The detect-count metric is only populated when DDoS Protection is actively
+    # inspecting traffic, so alerting requires ddos_protection enabled in log or
+    # block mode. (Cross-variable validation requires Terraform >= 1.9.)
+    condition = var.ddos_protection_alert == null || (
+      var.ddos_protection != null &&
+      var.ddos_protection.enabled &&
+      var.ddos_protection.mode != "off"
+    )
+    error_message = "ddos_protection_alert requires ddos_protection to be enabled with mode \"log\" or \"block\"."
+  }
+}
+
 ## NGWAF
 variable "legacy_edge_deployment" {
   type        = bool

google_fastly_waf/versions.tf

@@ -1,4 +1,8 @@
 terraform {
+  # >= 1.9 is required for cross-variable references in validation blocks
+  # (see ddos_protection_alert in variables.tf).
+  required_version = ">= 1.9"
+
   required_providers {
     fastly = {
       source  = "fastly/fastly"