Dawn is early in June. The chickens did not care that I had opinions about this.
A Raspberry Pi drives the door on a schedule — open at 06:00, closed at 19:00 by default — and I control it from a Telegram bot: open, close, stop, status, change the schedule, or ask it for a photo of the coop. It runs as a systemd unit so a power cut doesn't leave the birds shut in.
There was a small Flask app at first. The Telegram bot replaced it within a month, because the interface I actually wanted was my phone, from anywhere, without a VPN.
Tracking real sunrise would be better than a fixed schedule and is the obvious next change. Three years on I still haven't made it. In midsummer the door opens over an hour after first light and shuts more than two hours before dusk, and the chickens have not complained.