Feature Request: ability to wait for ephemeral instance to finish their execution

[lukerops]

In the docker container world, it is normal to have some init containers that run only once to initialize databases, run migrations or generate some config/secret files. When working with this type of init container workflow, I need to use the wait feature with a delay on an ephemeral instance and hope it works correctly.

[maveonair]

Could you provide more details on how you expect this feature to work? A minimal code example would help clarify your request.

Keep in mind that Incus runs a full OS with multiple processes, unlike OCI containers which typically focus on a single main process.

[lukerops]

I'm wanting something like this:

resource "incus_instance" "init" {
  name      = "instance-init"
  image     = "docker.io:debian/latest"
  ephemeral = true

  config = {
    "oci.entrypoint" = "/usr/bin/bash -c 'echo running command'"
  }
  
  wait_for {
    # make the terraform wait until the container ends successfully
    type = "execution"
  }
}

resource "incus_instance" "instance" {
  name      = "instance"
  image     = "docker.io:debian/latest"
  ephemeral = false

  config = {
    "oci.entrypoint" = "/usr/bin/tail -f /dev/null"
  }
  
  depends_on = [incus_instance.init]
}

This way, terraform will wait until the incus_instance.init finishes executing before starting the creation of incus_instance.instance.

Since incus_instance.init is marked as ephemeral, I expect that terraform doesn't try to recreate it when the first execution is marked as successfull.