Display plan/pre-apply warnings

Terraform Providers Plugin Development
1

Hello there! :v:

Is there a way to display warning during terraform plan or before approving terraform apply?

For example: Updating the RAM size of a VM requires it to be powered off. I would like to inform the user that the VM will be power-cycled when applying the changes (e.g. warn about potential data loss).

I tried checking for changes in the resource config in the ReadContextFunc , but it didn’t do anything:

func resourceRead(ctx context.Context, d *schema.ResourceData, m interface{}) diag.Diagnostics {
    // ...

    if d.hasChanges("foo") {
        diags = append(diags, diag.Diagnostics{
            Severity: diag.Warning,
            Summary: "Changing foo is a crime"
        }
    }

    // ...
}