content: FROM mcr.microsoft.com/dotnet/core/sdk:3.1
                     
  ENV MONO_VERSION 6.6.0.161
  
  RUN apt-get update \
    && apt-get install -y --no-install-recommends gnupg dirmngr \
    && rm -rf /var/lib/apt/lists/* \
    && export GNUPGHOME="$(mktemp -d)" \
    && gpg --batch --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF \
    && gpg --batch --export --armor 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF > /etc/apt/trusted.gpg.d/mono.gpg.asc \
    && gpgconf --kill all \
    && rm -rf "$GNUPGHOME" \
    && apt-key list | grep Xamarin \
    && apt-get purge -y --auto-remove gnupg dirmngr
  
  RUN echo "deb http://download.mono-project.com/repo/debian stable-stretch/snapshots/$MONO_VERSION main" > /etc/apt/sources.list.d/mono-official-stable.list \
    && apt-get update \
    && apt-get install -y mono-runtime \
    && rm -rf /var/lib/apt/lists/* /tmp/*
    
  # Install custom tools, runtime, etc. using apt-get
  # For example, the command below would install "bastet" - a command line tetris clone:
  #
  # RUN sudo apt-get -q update && #     sudo apt-get install -yq bastet && #     sudo rm -rf /var/lib/apt/lists/*
  #
  # More information: https://www.gitpod.io/docs/config-docker/
  