Cloud Run update image after creation

Terraform
1

I am trying to use Cloud Run with ESP V2. This requires me to

  1. Reserve a cloud run address by deploying a dummy cloud run instance.
  2. Use the address and API spec file to build an endpoints container image
  3. Update the service created at step 1 with the image created at step 2.

Extra details are https://cloud.google.com/endpoints/docs/openapi/get-started-cloud-run#reserve_hostname

Can you suggest a way to implement this using Terraform?
I don’t mind during this in two steps (having two terraform configurations). But I am not sure how to update an existing instance without creating it in the same terraform config. (the second one tries to recreate it).

Any help is highly appreciated.