This bash script is used on startup of a Docker container that is intended to simply provide and SSH endpoint within an app environment.

docker-ssh-config-and-run.sh

#!/usr/bin/env bash

# This script can add given users as SSH users. Use the following environment variables:
#   SSH_USERS="name1 name2 name3"
#   SSH_KEY_name1="ssh key for name1"
#   SSH_KEY_name2="ssh key for name2"
#   SSH_KEY_name3="ssh key for name3"

# You can set MYAPP on line 22 to any arbitrary string


function add_ssh_user
{
    newuser=$1
    newuserkey=$2

    echo "Adding $newuser as SSH user..."

    useradd -s /bin/bash -m $newuser
    adduser $newuser sudo
    su - $newuser -c "mkdir -p ~/.ssh && chmod 700 ~/.ssh"
    su - $newuser -c "echo '$newuserkey' > ~/.ssh/authorized_keys"
    su - $newuser -c "chmod 600 .ssh/authorized_keys"
    echo "$newuser ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers.d/MYAPP

    su - $newuser -c "touch ~/.ssh/environment"
    printenv | grep -v -E "^(USER|HOME|LOGNAME|PWD)=" >> /home/$newuser/.ssh/environment

    echo "User $newuser added successfully"
}

function run_sshd
{
    echo "running sshd in the foreground..."

    echo "installing openssh-server and sudo..."
    apt-get update && apt-get install -y openssh-server sudo
    mkdir /var/run/sshd

    if [ -n "$SSH_USERS" ]; then
      echo "adding at least one SSH user..."
      IFS=' ' read -r -a names <<< "$SSH_USERS"
      for name in "${names[@]}"
      do
          echo "adding SSH user $name..."
          key_name='SSH_KEY_'$name
          pub_key=$(printf '%s' "${!key_name}")
          add_ssh_user "$name" "$pub_key"
      done
      echo "completed adding SSH users"
    else
      echo "SSH_USERS not set, no users added for SSH"
    fi

    echo "PermitUserEnvironment=yes" >> /etc/ssh/sshd_config
    echo "ClientAliveInterval 600" >> /etc/ssh/sshd_config
    echo "ClientAliveCountMax 3" >> /etc/ssh/sshd_config

    /usr/sbin/sshd -e -p $SSH_PORT -D
}


run_sshd