Pretix Ticket Sales & Event Booking
Excellent piece of software, has been used in 2019 for wildweek of design schools.
Offer events, let people book, ticket sales (optional): https://pretix.eu/
Docker available https://github.com/pretix/pretix/blob/master/Dockerfile - install guide: https://docs.pretix.eu/en/latest/admin/installation/docker_smallscale.html