Enabling Asynchronous Operations

Even though Terraform uses multiple threads to run operations in parallel, each individual thread bringing a resource through its lifecycle states still needs to handle its operations synchronously. By default, when Terraform creates, updates, or deletes a resource it waits for that resource to reach its expected lifecycle state before proceeding. To avoid this waiting stage during Terraform operations, you can use an advanced option to create, update, or delete resources asynchronously.

To enable this feature, you can add the async = true flag to the resource. Terraform then considers creating or deleting as the target lifecycle stage. For example:

resource "oci_core_instance" "test_instance" {
  async               = true
  count               = var.num_instances
  availability_domain = data.oci_identity_availability_domain.ad.name
  compartment_id      = var.compartment_ocid
  display_name        = "TestInstance${count.index}"
  shape               = var.instance_shape
}

Use this feature for a faster way to create and delete resources in exchange for overriding Terraform's native behavior. When using the async option, consider that:

• The state file doesn't have the full information of the resource because the resource is not yet created.
• The resource's stage must be refreshed to get its full information, including whether the resource failed to be created.
• Terraform does not check the stage of a resource again after initiating its creation or deletion. Failed operations are only shown in subsequent refreshes of the resource.
• The asynchronous resource must have no dependencies, because the resource is not fully created before another operation begins.