SSH tunnel for Docker process

x-ssh-docker

#!/usr/local/bin/zsh

function sdocker() {
    E_RED='\033[0;31m'
    E_GREEN='\033[0;32m'
    E_YELLOW='\033[1;33m'
    E_NORMAL='\033[0m'

    function prinfo() {
        echo "${E_GREEN}=i=${E_NORMAL} $*"
    }

    function prerror() {
        echo "${E_RED}/e/${E_NORMAL} $*"
    }

    function prwarn() {
        echo "${E_YELLOW}/!/${E_NORMAL} $*"
    }

    function get_unused_port() {
      for port in $(seq 2780 2800);
      do
        echo -ne "\035" | nc 127.0.0.1 $port > /dev/null 2>&1;
        [ $? -eq 1 ] && echo "$port" && break;
      done
    }

    if [ -z "$DOCKER_HOST_NAME" ]; then
        prinfo "No existing connection. Proceeding ..."
    else
        prwarn "Shell already connected to $DOCKER_HOST_NAME"
        exit 1
    fi

    SOCKET_DIR=/tmp/x-ssh-docker
    SOCKET_PATH=$SOCKET_DIR/$1-conn.sock
    SERVER=$1


    DOCKER_PORT="$(get_unused_port)"

    [ -z "$SERVER" ] && \
        prinfo "Usage: x-ssh-docker <server>" && \
        exit 1

    [ -S "$SOCKET_PATH" ] && \
        prerror "Connection already exists."  && \
        prerror "Terminate connection command:" && \
        prinfo "ssh -S $SOCKET_PATH -O exit $SERVER" && \
        exit 1

    mkdir -p $SOCKET_DIR

    prinfo "Establishing background SSH connection tunnel to $SERVER ..."
    ssh -fNM -S $SOCKET_PATH -L $DOCKER_PORT:/var/run/docker.sock $SERVER

    if [ $? -eq 0 ]; then
        prinfo "Tunnel connected. Docker exposed via DOCKER_HOST=localhost:$DOCKER_PORT. Starting shell ..."
        DOCKER_HOST_NAME=$SERVER DOCKER_HOST=:$DOCKER_PORT /usr/local/bin/zsh

        ssh -S $SOCKET_PATH -O exit $SERVER
        prinfo  "Session completed. Closed connection to $SERVER."
    else
        prerror "Unable to setup tunnel."
    fi
}