When working with terraform loops you may encounter the error that is shown below.
The “for_each” value depends on resource attributes that cannot be determined until apply, so Terraform cannot predict how many instances will be created.
I faced this particular issue when I tried to dynamically create a azurerm_monitor_diagnostic_setting resource for multiple web apps.
The for_each code is shown below:
resource "azurerm_monitor_diagnostic_setting" "diag_settings_app" {
depends_on = [ azurerm_windows_web_app.app_service1,azurerm_windows_web_app.app_service2 ]
for_each = toset(local.app_service_ids)
name = "diag-rule"
target_resource_id = each.value
log_analytics_workspace_id = local.log_analytics_workspace_id
dynamic "log" {
iterator = entry
for_each = local.log_analytics_log_categories
content {
category = entry.value
enabled = true
retention_policy {
enabled = false
}
}
}
metric {
category = "AllMetrics"
retention_policy {
enabled = false
days = 30
}
}
}
The local.app_service_ids defines the app services IDs.
app_service_ids = [azurerm_windows_web_app.app_service1.id,azurerm_windows_web_app.app_service2.id]
In order to override this issue I used count loop instead.
resource "azurerm_monitor_diagnostic_setting" "diag_settings_app" {
depends_on = [ azurerm_windows_web_app.app_service1,azurerm_windows_web_app.app_service2 ]
count = length(local.app_service_ids)
name = "diag-rule"
target_resource_id = local.app_service_ids[count.index]
log_analytics_workspace_id = local.log_analytics_workspace_id
dynamic "log" {
iterator = entry
for_each = local.log_analytics_log_categories
content {
category = entry.value
enabled = true
retention_policy {
enabled = false
}
}
}
metric {
category = "AllMetrics"
retention_policy {
enabled = false
days = 30
}
}
}
terraform apply will then work:
