In the Azure API portal there is the Automation script tab, but that generates the ARM template for the entire resource group. It also includes a lot of other stuff that needed.
Is there a (simple) way to get hold of the ARM template for a specific API rather than the entire resource group? Can it be done through Azure cli? the REST API?
Yes, use the Azure Resource Explorer to locate your resource, the Uri at the top of the page will provide you a link to the template (requires authentication if you want to call it from outside of Resource Explorer).
I also always refer back to the reference documentation on ARM templates, it is a very good place to start from. Whilst it doesn't give you your exact template, it does give you a very clear base to start from (example below). I find this far more productive that trying to read the templates in the Automation Script" section of the portal.
Good luck.
