In terraform making string variable optional in action block - azure

Question

Hi i am creating alert rules. For some of the alerts i dont need to send any notification using action group.For that i need to make action group variable (string) as optional.
I tried using condition like var.action_group_id != null action_group_id : "". But i am getting following error.
Error: Can not parse "action.0.action_group_id" as a resource id: Cannot parse Azure ID: parse "null": invalid URI for request
And i tried making action block as dynamic block but it is not iterable. for_each is not supporting dynamic block with single variable with one values.
resource "azurerm_monitor_metric_alert" "keyvault_alert" {
for_each = var.keyvault_alert_rules
name = "${var.kv_name} - ${each.value.severity}"
resource_group_name = var.resource_group_name
description = each.value.description
scopes = var.alert_scope
severity = each.value.severity
frequency = each.value.frequency
`window_size = each.value.windowsize`
# criteria block
criteria {
metric_namespace = "Microsoft.KeyVault/vaults"
threshold = each.value.threshold
metric_name = each.value.metric_name
aggregation = each.value.aggregation
operator = each.value.operator
# dimension block
dynamic "dimension" {
for_each = each.value.dimension != null ? each.value.dimension : []
content {
name = dimension.value.dimensionname
operator = dimension.value.dimensionoperator
values = dimension.value.dimensionvalues
}
}
}
action {
action_group_id = var.action_group_id
}
variable.tf
variable "action_group_id" {
type = string
description = "ID of the action group"
}
variable "resource_group_name" {
type = string
description = "name of the resource group"
}
/* in the variables i am passing warning as n input.is there any way i can append warning to alert name in the main.tf based on the severity value which is given down below*/
variable "kv_alert_rules" {
type = map(object({
display_name = string
# display_name = "(severity numeric equalent ex:warning)-(metric name)"
#------details for the alert criteria
metric_name = string
operator = string
threshold = number
aggregation = string
#------ dimension vaules----------
dimension = list(object({
dimensionname = string
dimensionoperator = string
dimensionvalues = list(string)
}))
#-----------------------------------
severity = number
frequency = string
windowsize = string
# window size must be gretar than Frequency values be PT1M, PT5M, PT15M, PT30M, PT1H, PT6H, PT12H and P1D. Defaults to PT5M
description = string
}))
description = "This variable for alert criteria for key vault"
default = {
"Alert_1" = {
# display_name = "(severity numeric equalent ex:warning)-(generic word for metric name)"
display_name = "warning-used capacity"
severity = 2
dimension = null
metric_name = "SaturationShoebox"
aggregation = "Average"
frequency = "PT30M"
description = "Alert fires When Used vault capacity is GreaterThan 85"
windowsize = "PT1H"
operator = "GreaterThan"
threshold = 85
}
}
}
variable "kv_name" {
description = "key vault name "
type = string
}
module calling
module "keyvault" {
source = "../testing/key-vault-alert"
alert_scope = [data.azurerm_key_vault.examplekeyvault.id]
action_group_id = module.action-group.AGidout
resource_group_name = var.resource_group_name
kv_name = data.azurerm_key_vault.examplekeyvault.name
}
I would like to make action_group_id as optional variable.I dont wanna reference action group ID in some instances
If anyone knows a approach how to do that please guide me
Thanks

Answer 1

action is a dynamic block, so to make it optional you can do as follows:
dynamic "action" {
for_each = var.action_group_id != null ? [1] : []
content {
action_group_id = var.action_group_id
}
}