Dockerfile

FROM golang:1.22 AS download-gotty

RUN go install github.com/sorenisanerd/gotty@v1.5.0

FROM docker:26-dind

WORKDIR /app

COPY --from=download-gotty /go/bin/gotty /app/gotty

# https://stackoverflow.com/a/35613430
RUN mkdir /lib64 && ln -s /lib/libc.musl-x86_64.so.1 /lib64/ld-linux-x86-64.so.2

COPY start-shell.sh start-shell.sh
# create the same dockerfile for every challenge
RUN <<EOF
cat <<HEREDOC > Dockerfile
# The basic dockerfile that is loaded for each console.
# should take ~1MB per open console.
FROM ubuntu:22.04 

COPY SETUP.sh SETUP.sh
RUN bash SETUP.sh
RUN rm SETUP.sh

CMD ["/bin/bash"]
HEREDOC
EOF

# copy into image for setup (it will be deleted before the final image)
COPY SETUP.sh SETUP.sh

# run docker containers inside this docker container.
# therefore, each client is isolated from each other
CMD ["/app/gotty", "-w", "/bin/sh", "start-shell.sh"]

EXPOSE 8080