feat: sshnp_docker_demo

[JeremyTubongbanua]

What I did

• demo of sshnp between two docker containers (+1 more for sshrvd)

closes #96

[JeremyTubongbanua]

@natt-n followed the README.md and got it working!

[cpswan]

Rather than having fiddly instructions for people to specify their architecture the Dockerfiles should determine the architecture and act accordingly. When doing RUN commands this can generally be achieved with a case statement based on uname -m e.g. we use this for the Dockerfile.package in sshnoports:

RUN set -eux; \
    case "$(dpkg --print-architecture)" in \
        amd64) \
            ARCH="x64";; \
        armhf) \
            ARCH="arm";; \
        arm64) \
            ARCH="arm64";; \
        riscv64) \
            ARCH="riscv64";; \
    esac; \
    mkdir sshnp; \
    mkdir tarball; \
    dart pub get; \
    dart compile exe bin/activate_cli.dart -v -o sshnp/at_activate; \
    dart compile exe bin/sshnp.dart -v -o sshnp/sshnp; \
    dart compile exe bin/sshnpd.dart -v -o sshnp/sshnpd; \
    dart compile exe bin/sshrv.dart -v -o sshnp/sshrv; \
    dart compile exe bin/sshrvd.dart -v -o sshnp/sshrvd; \
    cp scripts/* sshnp; \
    tar -cvzf tarball/sshnp-linux-${ARCH}.tgz sshnp

It's also possible to use the TARGETPLATFORM ARG variable that gets passed in to a build like this:

ARG TARGETPLATFORM
RUN case ${TARGETPLATFORM} in \
         "linux/amd64")  ARCH=amd64  ;; \
         "linux/arm64")  ARCH=arm64  ;; \
         "linux/arm/v7") ARCH=armhf  ;; \
         "linux/arm/v6") ARCH=armel  ;; \
         "linux/386")    ARCH=i386   ;; \
    esac \
 && wget -q https://github.com/org/thing/releases/download/${VERSION}/whatever-${ARCH} -O /thing

More generally it's considered good practice to have multi line RUN statements rather than many of them, as each command in a Dockerfile creates a new layer in the resulting image.

[JeremyTubongbanua]

@cpswan I have

1. refactored README to use @XavierChanth's work with the sshnpd/sshnp installers
2. sshnp_docker_demo_base GHA
3. docker-build script tries to pull base image from docker hub

# try to docker pull, if it doesn't work, build local image
sudo docker pull $BASE_IMAGE_NAME
if [ $? -ne 0 ]
then
    echo "Could not pull $BASE_IMAGE_NAME. Building local image."
    sudo docker build -t $BASE_IMAGE_NAME -f ../demo-base/Dockerfile ../demo-base
fi

4. Dockerfile no longer installs binaries (as installers do that for you)

[cpswan]

Just a few nits, and then I think we're ready to merge