install

#!/usr/bin/env bash
set -eo pipefail; [[ -n "$PLUSHU_TRACE" ]] && set -x

echo_install_information () {
  local distro=""
  if [[ -f /etc/os-release ]]; then
   distro=`sed -n 's/^ID=\(.*\)$/\1/p' /etc/os-release`
  fi
  case "$distro" in
    arch)
      cat <<"EOF"
To install Docker on Arch Linux, run

# pacman -S docker

See http://docs.docker.com/installation/archlinux/ for more info.
EOF
      ;;
    ubuntu)
      cat <<"EOF"
To install Docker on Ubuntu, run

$ curl -s https://get.docker.io/ubuntu/ | sudo sh

See http://docs.docker.com/installation/ubuntulinux/ for more info.
EOF
      ;;
    *)
      cat <<"EOF"
Look up how to install Docker on your system:
  http://docs.docker.com/installation/
EOF
      ;;
  esac
}

check_docker_run_status () {
  if command -v systemctl >/dev/null 2>&1; then
    if systemctl -q is-enabled docker.service; then
      echo "Docker is enabled via systemctl... good."
    else
      echo "Docker does not appear to be enabled. Enable it with:"
      echo
      echo "# systemctl enable docker.service"
      echo
    fi
    if systemctl -q is-active docker.service; then
      echo "Docker is currently running... good."
    else
      echo "Docker does not appear to be currently running. Start it with:"
      echo
      echo "# systemctl start docker.service"
      echo
    fi
  else
    if pgrep -x docker >/dev/null 2>&1; then
      echo "Docker appears to be running... good."
    else
      echo "Docker doesn't appear to be running."
      echo "You should start it with something like:"
      echo
      echo "# service start docker"
      echo
    fi
    echo "Make sure Docker is set to run automatically at startup."
  fi
}

add_plushu_user_to_docker_group () {
  if id -Gn "$PLUSHU_USER" | grep -q '\bdocker\b'; then
    echo "plushu is a member of the docker group... good."
  else
    if [[ "$EUID" == 0 ]]; then
      echo "Adding plushu to the docker group..."
      usermod -aG docker "$PLUSHU_USER"
    else
      echo "plushu is not a member of the docker group."
      echo "To create it, reinstall this plugin as root, or run:"
      echo
      echo "# groupadd docker"
    fi
  fi
}

setup_docker_for_plushu () {
  if egrep -i "^docker" /etc/group; then
    echo "docker group already exists... good."
    add_plushu_user_to_docker_group
  else
    if [[ "$EUID" == 0 ]]; then
      echo "docker group does not already exist, creating it..."
      groupadd docker
      add_plushu_user_to_docker_group
    else
      cat <<EOF
The \"docker\" user group does not already exist.
To create it, reinstall this plugin as root, or run:

# groupadd docker

After you have created the docker group, the plushu user will need to be added
to it for access to Docker. Either re-install the plugin as root, or add
plushu to the group with:

# usermod -aG docker plushu
EOF
    fi
  fi
  check_docker_run_status
}

check_for_docker_dot_io () {
  # If docker.io is present (the name it's installed to for Ubuntu)
  if [[ -x /usr/bin/docker.io ]]; then
    cat <<"EOF"
The Docker we want appears to be at /usr/bin/docker.io rather than somewhere
where it can be called as "docker".
EOF
    if [[ "$EUID" == 0 ]]; then
      echo "Creating symlink for plushu..."
      ln -sf /usr/bin/docker.io "$PLUSHU_ROOT/bin/docker"
    else
      cat <<EOF
You can fix this system-wide by running:

# ln -sf /usr/bin/docker.io /usr/local/bin/docker

Or, if you re-run this script as root, docker will be linked just for plushu,
as $PLUSHU_ROOT/bin/docker.
EOF
    fi

  else
    echo "Docker does not appear to be installed."
    echo_install_information
  fi
}

# if Docker is present
if command -v docker >/dev/null 2>&1; then

  # If it exits 0 when run as `docker -v`
  if docker -v >/dev/null 2>&1; then
    echo "Docker appears to be installed... good."
    setup_docker_for_plushu

  # If it exits non-zero when run as `docker -v` (the tray app that goes by
  # "Docker" exits with a status of 2)
  else
    cat <<"EOF"
It looks like `docker` on your system refers to the system tray application
known as Docker (http://icculus.org/openbox/2/docker/), rather than the
Docker we want (https://www.docker.com/).
EOF
    check_for_docker_dot_io
  fi
else
  check_for_docker_dot_io
fi