message: Set watchtower to update/watch only shadowbox container
diff: @@ -261,6 +261,7 @@ function start_shadowbox() {
  # rather than pass in the environment.
  declare -a docker_shadowbox_flags=(
  --name shadowbox --restart=always --net=host
  + --label=com.centurylinklabs.watchtower.enable=true
  -v "${STATE_DIR}:${STATE_DIR}"
  -e "SB_STATE_DIR=${STATE_DIR}"
  -e "SB_API_PORT=${API_PORT}"
  @@ -295,7 +296,7 @@ function start_watchtower() {
  docker_watchtower_flags+=(-v /var/run/docker.sock:/var/run/docker.sock)
  # By itself, local messes up the return code.
  local readonly STDERR_OUTPUT
  - STDERR_OUTPUT=$(docker run -d "${docker_watchtower_flags[@]}" containrrr/watchtower --cleanup --tlsverify --interval $WATCHTOWER_REFRESH_SECONDS 2>&1 >/dev/null)
  + STDERR_OUTPUT=$(docker run -d "${docker_watchtower_flags[@]}" containrrr/watchtower --cleanup --label-enable --tlsverify --interval $WATCHTOWER_REFRESH_SECONDS 2>&1 >/dev/null)
  local readonly RET=$?
  if [[ $RET -eq 0 ]]; then
  return 0
  