Thanks for the response, this is by far the most helpful information I've received yet. I will try to create my own requestHandler. Do you know where in the code base is the logic that displays that "choose search source" page? I would like to reuse that before adding my own logic to query es if possible. I know it appears when you add the requestHandler: 'courier' code, but I can't find the source for where it displays that page, or how it works in general.
Unfortunately the current experience for building custom visualizations can be difficult to follow, and could be much better documented
This would be greatly helped if it was possible for someone to publish a more up to date blog on creating custom visualisations, for something along the lines of what I am trying to do (a vis that simply queries es for docs and just displays them on the screen). Most of the resources with examples I've found are blogs that are 2-3 years old, and there seems to have been quite the change in the process since then. Even the more up to date code examples I have been able to find have been hidden in the source code in the most bizarre places, and I've only been able to find them thanks to people on this forum. I'd happily raise a ticket or a request for a more up to date blog on the process, if you could point me in a direction of somewhere to raise it, just so the ELK team are aware it would help developers 