In teraform, is there a way to refresh the state of a resource using TF files without using CLI commands? - import

Question

I have a requirement to refresh the state of a resource "ibm_is_image" using TF files without using CLI commands ?
I know that we can import the state of a resource using "terraform import ". But I should do the same using IaC in TF files.
How to achieve this ?
Example:
In workspace1, I create a resource "f5_custom_image" which gets deleted later from command line. In workspace2, the same code in TF file will assume that "f5_custom_image" already exists and it fails to read the custom image resource. So, my code has to refresh the terraform state of this resource for every execution of "terraform apply":
resource "ibm_is_image" "f5_custom_image" {
depends_on = ["data.ibm_is_images.custom_images"]
href = "${local.image_url}"
name = "${var.vnf_vpc_image_name}"
operating_system = "centos-7-amd64"
timeouts {
create = "30m"
delete = "10m"
}
}

Answer 1

In Terraform's model, an object is fully managed by a single Terraform configuration and nothing else. Having an object be managed by multiple configurations or having an object be created by Terraform but then deleted later outside of Terraform is not a supported workflow.
Terraform is intended for managing long-lived architecture that you will gradually update over time. It is not designed to manage build artifacts like machine images that tend to be created, used, and then destroyed.
The usual architecture for this sort of use-case is to consider the creation of the image as a "build" step, carried out using some other software outside of Terraform, and then we use Terraform only for the "deploy" step, at which point the long-lived infrastructure is either created or updated to use the new image.
That leads to a build and deploy pipeline with a series of steps like this:
Use separate image build software to construct the image, and record the id somewhere from which it can be retrieved using a data source in Terraform.
Run terraform apply to update the long-lived infrastructure to make use of the new image. The Terraform configuration should include a data block to read the image id from wherever it was recorded in the previous step.
If desired, destroy the image using software outside of Terraform once Terraform has completed.
When implementing a pipeline like this, it's optional but common to also consider a "rollback" process to use in case the new image is faulty:
Reset the recorded image id that Terraform is reading from back to the id that was stored prior to the new build step.
Run terraform apply to update the long-lived infrastructure back to using the old image.
Of course, supporting that would require retaining the previous image long enough to prove that the new image is functioning correctly, so the normal build and deploy pipeline would need to retain at least one historical image per run to roll back to. With that said, if you have a means to quickly recreate a prior image during rollback then this special workflow isn't strictly needed: instead, you can implement rollback instead by "rolling forward" to an image constructed with the prior configuration.
An example software package commonly used to prepare images for use with Terraform on other cloud vendors is HashiCorp Packer, but sadly it looks like it does not have IBM Cloud support and so you may need to look for some similar software that does support IBM Cloud, or write something yourself using the IBM Cloud SDK.