The German government tasked SAP and Deutsche Telekom with the development of an open-source contact tracing app (named “Corona-Warn-App”) using the APIs from Google and Apple. Now they’ve published the code for the backend server. I took a quick look at the code and I’m quite a bit surprised about the quality and best practices used. They are using the Java-based Spring framework and use Postgres and minio to store data. Everything running in Docker. Even the Docker images are build using multi-stage Dockerfiles.