Dockerfile

FROM ubuntu:16.04
MAINTAINER Thomas Runting <tom@tomrunting.pro>

# create user for steam
RUN adduser \
	--home /home/steam \
	--disabled-password \
	--shell /bin/bash \
	--gecos "user for running steam" \
	--quiet \
	steam

# install dependencies
RUN apt-get update && \
    apt-get install -y curl lib32gcc1 && \
    apt-get clean && \
    rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*

# Downloading SteamCMD and make the Steam directory owned by the steam user
RUN mkdir -p /opt/steamcmd &&\
    cd /opt/steamcmd &&\
    curl -s http://media.steampowered.com/installer/steamcmd_linux.tar.gz | tar -vxz &&\
    chown -R steam /opt/steamcmd &&\
    mkdir -p /opt/steamapps/FortressCraft &&\
    chown -R steam /opt/steamapps


# SteamCMD should not be used as root, here we set up user and variables
USER steam
WORKDIR /opt/steamcmd

RUN  /opt/steamcmd/steamcmd.sh +login anonymous +force_install_dir /opt/steamapps/FortressCraft +app_update 443600 -beta linux_server_headless validate +quit

#VOLUME [ "/users/steam/.config/unity3d/ProjectorGames/" ]

# Execution vector
#ENTRYPOINT ["/opt/steamcmd/steamcmd.sh +login anonymous"]
ENTRYPOINT [ "/opt/steamcmd/FortressCraft/FC_Linux_Universal.x86_64" ]