FROM ubuntu:20.04
RUN apt-get update && apt-get install -y openssh-server
RUN mkdir /var/run/sshd

# Con sshd, ENV no funciona. Para fijar una variable de entorno:
# RUN echo "export MI_VARIABLE=mivalor" >> /etc/profile
COPY entrypoint.sh /

EXPOSE 22
ENTRYPOINT ["/entrypoint.sh"]