Stunnel is a "proxy designed to add TLS encryption functionality to existing clients and servers without any changes in the programs' code".

This Dockerfile allows it to run on an Alpine Linux container.

cd alpine
docker build -t stunnel .
docker run -p <container port>:<local port> -e "STUNNEL_CONF=<configuration>" stunnel

If a new version of Stunnel (Alpine package) or new version of Alpine Linux is released, update .github/workflows/build_alpine_images.yml to include the new versions in the build matrix.