A personalised, auto-updating iCalendar of Danish electricity prices which you can subscribe to via a compatible application, e.g. Calendar on macOS.
The dk.simongray.el.prices namespace is a micro-library for sourcing the latest Danish electricity prices, while dk.simongray.el.calendar contains a small Pedestal web service exposing the calendar itself.
Caddy must be installed, along with Clojure and a JVM of course.
The production system is compiled from source using xcaddy in order to allow rate-limiting, since Caddy doesn't provide this feature built in. My chosen rate limiting extension is the one by RussellLuo as it was the simplest to implement. Compiling a custom Caddy binary requires both Go and xcaddy to be installed:
xcaddy build --with github.com/RussellLuo/caddy-ext/ratelimit
cp ./caddy /usr/bin/caddyAssuming that the calendar web service is already running in a Clojure REPL:
# local reverse proxy
caddy runApple's Calendar app won't like the fact that localhost has a subdomain (el.localhost), so the actual calendar subscription will fail for that reason. However, subscribing via localhost:9876 can be used to verify that the service works as intended.
Either upload via SFTP or build an uberjar called el.jar. The uberjar is created by running the ci function in dev/src/build.clj. This .jar file needs to be located in /opt/el on the server.
To save on server resources, it's probably best to build el.jar on the dev machine and upload it to the server. Running an uberjar (as opposed to running via /usr/local/bin/clojure -Xserver, which I did originally) is much more performant.
Copy Systemd units and Caddyfile:
# from inside the `el` directory
sh install.shSystemd setup:
# enable systemd units (just once)
systemctl enable el
systemctl enable caddyStarting the system:
# start services (as needed)
systemctl start el
systemctl start caddy
# ..or do a manual caddy run (debugging only)
DOMAIN=simongray.dk caddy run