The big picture

The diagram below describes the architecture of the immich RPi server and how different parts of the system communicate.

data-flow-diagram

Glossary

Raspberry Pi (RPi): A small and cheap single-board computer.
Immich: The code that runs on our RPi providing photo management features.
External drive: A Solid State Drive (SSD) or Hard Disk Drive (HDD) with a USB interface.
Cloud storage: A storage service provided by third parties such as Proton Drive, Backblaze, GCP, AWS, etc.
rclone/rustic: Programs that facilitate backups to cloud storage.
tailscale: VPN that allows our server to be reachable from anywhere.