feat: [P4PU-680] added allarm for redis (#63)

Co-authored-by: antonioT90 <[email protected]>

src/06_domains/cittadini-app/00_data.tf

@@ -38,4 +38,9 @@ data "azurerm_key_vault_secret" "appinsights_connection_string" {
 data "azurerm_log_analytics_workspace" "log_analytics" {
   name                = local.log_analytics_name
   resource_group_name = local.monitor_resource_group_name
+}
+
+data "azurerm_redis_cache" "redis_common" {
+  name                = "${local.project}-redis"
+  resource_group_name = "${local.project}-redis-rg"
 }

src/06_domains/cittadini-app/12_alert.tf

@@ -118,5 +118,32 @@ resource "azurerm_monitor_metric_alert" "ram_cluster_usage" {
     action_group_id = azurerm_monitor_action_group.slack_cittadini[0].id
   }
 
+  tags = var.tags
+}
+
+resource "azurerm_monitor_metric_alert" "redis_server_load" {
+  count = var.alert_enabled ? 1 : 0
+
+  name                = "${local.project}-redis-server-load"
+  resource_group_name = data.azurerm_resource_group.monitor_rg.name
+
+  scopes      = [data.azurerm_redis_cache.redis_common.id]
+  severity    = 0
+  frequency   = "PT15M"
+  window_size = "PT30M"
+  criteria {
+    metric_namespace = "Microsoft.Cache/redis"
+    metric_name      = "allserverLoad"
+    aggregation      = "Average"
+    threshold        = 80
+    operator         = "GreaterThan"
+  }
+
+  description = "Trigger alert when Redis serve usage is greater than 80%"
+  enabled     = true
+  action {
+    action_group_id = azurerm_monitor_action_group.slack_cittadini[0].id
+  }
+
   tags = var.tags
 }