How to run the backend server/code in re-frame template?

Using lein re-frame template I see that there's a -main function that runs a jetty server for the backend code located in clj/. Using emacs I've been able to cider-jack-in-cljs and get the frontend running in the browser, hot reload works and all but I've tried to add routes to the routes function in handler.clj inside the clj/ and haven't been able to figure out how to get that "backend side" of things to work.

I found this other question sort of related but in that case the user just wanted to know why the clj/ folder was there, not how to run that code. I haven't been able to find any documentation so far, any help is greatly appreciated.

PD: I know that having the backend and frontend in the same project/repo is not recommended (it's mentioned in the other question I linked above) but I just want to get a simple "first app" working and running first and then hopefully get the backend out into another project/repo.

Assuming you created the project with something like lein new re-frame myapp +handler the code to start the server is on the file src/clj/myapp/server.clj

You can open the file and run cider-jack-in-clj, which will ask if you want to launch lein or shadow-cljs. Since it's a CLJ file, choose lein. Once CIDER starts, you can evaluate the -main function (eg. (-main)) to start the server.

You can open the URL at http://localhost:3000 and Jetty will serve the resources that are already compiled by shadow-cljs, so you'll see the same output as viewing the other port from CLJS directly.

Note that the backend code from the template starts the Jetty server but won't help with reloading the backend. To see how enable hot reloading for the backend, check https://github.com/ring-clojure/ring/wiki/Setup-for-development