Add existing alerts (#472)

terraform/alerting/notifications.tf

@@ -0,0 +1,9 @@
+resource "google_monitoring_notification_channel" "email" {
+  provider     = google-beta
+  project      = var.project
+  display_name = "Email Notification Channel"
+  type         = "email"
+  labels = {
+    email_address = var.notification-email
+  }
+}

terraform/alerting/probers.tf

@@ -0,0 +1,66 @@
+resource "google_monitoring_uptime_check_config" "https" {
+  for_each = toset([var.server-host, var.apiserver-host, var.adminapi-host])
+
+  display_name = each.key
+  timeout      = "3s"
+  project      = var.project
+  period       = "60s"
+
+  http_check {
+    path         = "/health"
+    port         = "443"
+    use_ssl      = true
+    validate_ssl = true
+  }
+
+  monitored_resource {
+    type = "uptime_url"
+    labels = {
+      project_id = var.project
+      host       = each.key
+    }
+  }
+}
+
+resource "google_monitoring_alert_policy" "probers" {
+  project      = var.project
+  display_name = "Host Down"
+  combiner     = "OR"
+  conditions {
+    display_name = "Host is unreachable"
+    condition_threshold {
+      duration        = "300s"
+      threshold_value = 0.2
+      comparison      = "COMPARISON_LT"
+      filter          = "metric.type=\"monitoring.googleapis.com/uptime_check/check_passed\" resource.type=\"uptime_url\""
+
+      aggregations {
+        alignment_period     = "60s"
+        cross_series_reducer = "REDUCE_FRACTION_TRUE"
+        group_by_fields = [
+          "resource.label.host",
+        ]
+        per_series_aligner = "ALIGN_NEXT_OLDER"
+      }
+
+      trigger {
+        count = 1
+      }
+    }
+  }
+
+  documentation {
+    content   = <<-EOT
+## $${policy.display_name}
+
+[$${resource.label.host}](https://$${resource.label.host}/health) is being reported unreachable.
+
+See [docs/hosts.md](https://github.com/sethvargo/exposure-notifications-server-infra/blob/main/docs/hosts.md) for information about hosts.
+EOT
+    mime_type = "text/markdown"
+  }
+
+  notification_channels = [
+    google_monitoring_notification_channel.email.id
+  ]
+}

terraform/alerting/variables.tf

@@ -0,0 +1,42 @@
+variable "project" {
+  type = string
+}
+
+variable "notification-email" {
+  type        = string
+  default     = "nobody@example.com"
+  description = "Email address for alerts"
+}
+
+variable "server-host" {
+  type        = string
+  default     = ""
+  description = "Domain web ui is hosted on."
+}
+
+variable "apiserver-host" {
+  type        = string
+  default     = ""
+  description = "Domain apiserver is hosted on."
+}
+
+variable "adminapi-host" {
+  type        = string
+  default     = ""
+  description = "Domain adminapi is hosted on."
+}
+
+terraform {
+  required_version = ">= 0.13"
+
+  required_providers {
+    google = {
+      source  = "hashicorp/google"
+      version = "~> 3.36"
+    }
+    google-beta = {
+      source  = "hashicorp/google-beta"
+      version = "~> 3.36"
+    }
+  }
+}