A complete (but w/o mysql and only the tf2 sdk) docker build environment for compiling sourcemod (1.8-dev branch) and its extensions, controlled by SSH.

sourcemod-buildenv.Dockerfile

FROM ubuntu

RUN apt update && apt upgrade -y && \
    apt install -y git \
                   lib32stdc++6 \
                   lib32z1-dev \
                   libc6-dev-i386 \
                   linux-libc-dev \
                   lib32gcc-5-dev \
                   libgcc-5-dev \
                   g++-5-multilib \
                   gcc-5-multilib \
                   g++-5 \
                   gcc-5 \
                   python3 \
                    \
                   openssh-server \
                   python3-pip && \
    mkdir /var/run/sshd && chmod 0755 /var/run/sshd

RUN sed -i "s/.*RSAAuthentication.*/RSAAuthentication yes/g" /etc/ssh/sshd_config && \
    sed -i "s/.*PubkeyAuthentication.*/PubkeyAuthentication yes/g" /etc/ssh/sshd_config && \
    sed -i "s/.*PasswordAuthentication.*/PasswordAuthentication no/g" /etc/ssh/sshd_config && \
    sed -i "s/.*AuthorizedKeysFile.*/AuthorizedKeysFile\t\.ssh\/authorized_keys/g" /etc/ssh/sshd_config && \
    sed -i "s/.*PermitRootLogin.*/PermitRootLogin no/g" /etc/ssh/sshd_config
#Supply your own public key for authenticating
ADD id.pub /tmp/id.pub

RUN useradd -U -d /home/build -s /bin/bash build && \
    mkdir /home/build && chown build:build /home/build && \
    su build -c bash -c "mkdir /home/build/.ssh/ && \
    cat /tmp/id.pub > /home/build/.ssh/authorized_keys"

RUN su build -c bash -c \
    "git clone --branch 1.8-dev --recursive https://github.com/alliedmodders/sourcemod      /home/build/sourcemod && \
     git clone --branch tf2                 https://github.com/alliedmodders/hl2sdk         /home/build/hl2sdk-tf2 && \
     git clone --branch 1.10-dev            https://github.com/alliedmodders/metamod-source /home/build/mmsource-1.10" && \
    git clone https://github.com/alliedmodders/ambuild /tmp/ambuild
RUN cd /tmp/ambuild && python3 setup.py install

EXPOSE 22
CMD ["/usr/sbin/sshd", "-D"]