Shell script for Docker Desktop users to draw a Christmas tree in Docker Desktop using container names on the Containers tab

docker-desktop-christmas.sh

#!/usr/bin/env bash

# Video: https://youtu.be/_wMgTx9pRVg

set -eu -o pipefail

tree_width=40
tree_character="X"
tree_trunk_character="M"

# console chars
empty_character=".."
border_character="I"
console_width=$(( tree_width + 10 ))
console_height="12"

console_line_ids=()
console_line_number=1

label="hu.rimelek.docker-christmas"

function console_render_line() {
  local line="$1"
  local delay_ms="${2:-300}"

  local line_count="${#console_line_ids[@]}"

  if (( line_count == console_height )); then
    docker rm -f "${console_line_ids[0]}"
    console_line_ids=("${console_line_ids[@]:1}")
  fi

  line="$(printf "%03d" $console_line_number)${empty_character}$line"

  console_line_ids+=(
    "$(docker create \
      --name "$line" \
      --label hu.rimelek.docker-christmas \
      bash)"
  )
  (( ++console_line_number ))
}

function console_padding() {
  local text="$1"
  local text_length="${#text}"
  local align="${2:-right}"

  local padding_size="$(( console_width - text_length ))"
  case "$align" in
    center)
      local padding_left_size="$(( padding_size / 2 ))"
      local padding_right_size="$(( console_width - (padding_left_size + text_length) ))"
      if [[ "$padding_left_size" != "0" ]]; then
        echo -n "$(printf -- "${empty_character}%.0s" $(seq 1 "$padding_left_size"))"
      fi
      echo -n "${text}"
      if [[ "$padding_right_size" != "0" ]]; then
        echo -n "$(printf -- "${empty_character}%.0s" $(seq 1 "$padding_right_size"))"
      fi
      ;;
    left)
      if [[ "$padding_size" != "0" ]]; then
        echo -n "$(printf -- "${empty_character}%.0s" $(seq 1 "$padding_size"))"
      fi
      echo -n "${text}"
      ;;
    *)
      echo -n "${text}"
      if [[ "$padding_size" != "0" ]]; then
        echo -n "$(printf -- "${empty_character}%.0s" $(seq 1 "$padding_size"))"
      fi
      ;;
  esac
}

function text_align() {
  local text="${1:-}"
  local align="${2:-left}"
  local align_map
  declare -A align_map
  align_map["left"]=right
  align_map["center"]=center
  align_map["right"]=left
  echo -n "$(console_padding "$text" "${align_map[$align]}")"
}

function console_writeln() {
  local text="${1:-}"
  local align="${2:-left}"
  console_render_line "${border_character}$(text_align "$text" "$align")${border_character}"
}

function draw_tree_top() {
  local number_start=1
  local number_end=$(( tree_width / 4 ))
  local line_width
  local i

  i=$number_start
  while (( i <= number_end )); do
    line_width=$(( i * 4 ))
    console_writeln "$(printf -- "${tree_character}%.0s" $(seq 1 $line_width))" "center"
    sleep 0.2
    (( ++i ))
  done
}

function draw_tree_bottom() {
  local number_start=1
  local number_end=2
  local i

  i=$number_start
  while (( i <= number_end )); do
    console_writeln "$(printf -- "${tree_trunk_character}%.0s" $(seq 1 4))" "center"
    (( ++i ))
    sleep 0.2
  done
}

function draw_merry_christmas() {
  console_writeln ""
  console_writeln "M_E_R_R_Y__C_H_R_I_S_T_M_A_S" "center"
  console_writeln "D_O_C_K_E_R__U_S_E_R_S" "center"
  sleep 1
  console_writeln "O_R" "center"
  sleep 1
  console_writeln "J_U_S_T__A__H_A_P_P_Y__D_A_Y" "center"
  console_writeln ""
  sleep 3
}

for i in $(seq 1 3); do
  draw_tree_top
  draw_tree_bottom
  draw_merry_christmas
done
console_writeln ""
console_writeln ""
console_writeln "CONTAINERS__WILL__BE__DELETED" "center"
console_writeln "IN__20__SECONDS" "center"
sleep 20

docker container ls -a -q --filter label="$label" | xargs -- docker container rm -f