Azure Alert Creation Via terraform fails with error code 400 - azure

Question

While creating metric alert on storage account via terraform I am getting Error 400
I've gone through the documentation and corss-verified that the name I am using for alert creation is correct
resource "azurerm_metric_alertrule" "test" {
name = "alerttestacc"
resource_group_name = "${azurerm_resource_group.main.name}"
location = "${azurerm_resource_group.main.location}"
description = "An alert rule to watch the metric Used capacity"
enabled = true
resource_id = "${azurerm_storage_account.to_monitor.id}"
metric_name = "UsedCapacity"
operator = "GreaterThan"
threshold = 20
aggregation = "Total"
period = "PT5M"
email_action {
send_to_service_owners = false
custom_emails = [
"xyz#gmail.com",
]
}
webhook_action {
service_uri = "https://example.com/some-url"
properties = {
severity = "incredible"
acceptance_test = "true"
}
}
Expected: Alert should be created
Actual:
azurerm_metric_alertrule.test:
insights.AlertRulesClient#CreateOrUpdate: Failure responding to
request: StatusCode=400 -- Original Error: autorest/azure: Service
returned an error. Status=400 Code="UnsupportedMetric" Message="The
metric with namespace '' and name 'UsedCapacity' is not supported for
this resource id

Answer 1

You could use azurerm_monitor_metric_alert instead of azurerm_metric_alertrule to create a UsedCapacity metric alert for the storage account. It is possible due to the different experiences between classic alerts and new alerts in Azure monitoring. Read alerts overview.
This example works on my side.
resource "azurerm_resource_group" "main" {
name = "example-resources"
location = "West US"
}
resource "azurerm_storage_account" "to_monitor" {
name = "examplestorageaccount123"
resource_group_name = "${azurerm_resource_group.main.name}"
location = "${azurerm_resource_group.main.location}"
account_tier = "Standard"
account_replication_type = "LRS"
}
resource "azurerm_monitor_action_group" "main" {
name = "example-actiongroup"
resource_group_name = "${azurerm_resource_group.main.name}"
short_name = "exampleact"
webhook_receiver {
name = "callmyapi"
service_uri = "http://example.com/alert"
}
}
resource "azurerm_monitor_metric_alert" "test" {
name = "example-metricalert"
resource_group_name = "${azurerm_resource_group.main.name}"
scopes = ["${azurerm_storage_account.to_monitor.id}"]
description = "Action will be triggered when the Used capacity is Greater than 777 bytes."
criteria {
metric_namespace = "Microsoft.Storage/storageAccounts"
metric_name = "UsedCapacity"
aggregation = "Total"
operator = "GreaterThan"
threshold = 777
}
action {
action_group_id = "${azurerm_monitor_action_group.main.id}"
}
}