Update the WebUI theme inside a qBittorrent container. The cjratliff theme is hardcoded, so modify the script if another one is used.

update-theme.sh

#!/usr/bin/env bash

# ============================================================================= #
# Copyright © 2025 Guiorgy                                                      #
#                                                                               #
# This program is free software: you can redistribute it and/or modify it under #
# the terms of the GNU General Public License as published by the Free Software #
# Foundation, either version 3 of the License, or (at your option) any later    #
# version.                                                                      #
#                                                                               #
# This program is distributed in the hope that it will be useful, but WITHOUT   #
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS #
# FOR A PARTICULAR PURPOSE.                                                     #
#                                                                               #
# You can see the full GNU General Public License at                            #
# <https://www.gnu.org/licenses/> for more details.                             #
# ============================================================================= #

# Usage:
#  - Place the script inside the config volume, e.g. /va/lib/docker/volumes/qbittorrent_config/_data
#  - Make it executable, e.g chmod +x ./update-theme.sh
#  - Stop the container before updating the theme, e.g. docker stop qBittorrent
#    In order to apply the theme the container needs to be restarted, but when stopping, the current config
#    is saved into the config file, overwriting any changes made while the container was running.
#  - Apply the new theme by executing the script, e.g. sudo -u 1000 ./update-theme.sh
#  - Start the stopped container, e.g. docker start qBittorrent

NC='\033[0m' # reset
ERR='\033[0;31m' # red
OK='\033[0;32m' # green
WARN='\033[0;33m' # yellow
ACC='\033[0;94m' # bright blue

if [[ "$UID" -ne '1000' ]]; then
  echo -e "${ERR}Error${NC}: This script must be run by the user with UID ${ACC}1000${NC} (${ACC}qbtUser${NC})" 1>&2
  exit 1
fi
cd "$(dirname -- "$0")"

set -Eeo pipefail

handle_error() {
  error_code=$?
  echo -e "${ERR}Script failed on line #${1} with error code ${error_code}!${NC}" 1>&2
  exit $error_code
}

trap 'handle_error $LINENO' ERR

print() {
  COLOR="$WARN"

  if [[ $# -gt 1 ]]; then
    case "$1" in
      --*)
        case "$1" in
          --no-color) COLOR="$NC" ;;
          --error) COLOR="$ERR" ;;
          --ok) COLOR="$OK" ;;
          --warn) COLOR="$WARN" ;;
          --accent) COLOR="$ACC" ;;
          *) error 'Unrecognized color' ;;
        esac

        shift
      ;;
      *) ;;
    esac
  fi

  if [[ $# -gt 1 ]]; then
    if [[ -n "$1" ]]; then
      echo -e -n "${COLOR}${1}${NC}: "
    fi
    shift
  fi
  echo -e "$1"
}

error() {
  print --error 'Error' "${1}" 1>&2

  if [[ -n "$2" ]]; then
    exit "$2"
  else
    exit 1
  fi
}

releaseTag="$1"
if [[ -z "$releaseTag" ]]; then
  print 'Getting the latest release tag from GitHub'
  response=$(curl --silent --show-error 'https://api.github.com/repos/Carve/qbittorrent-webui-cjratliff.com/releases/latest')
  releaseTag=$(grep -m 1 '"tag_name"' <<< "$response" | cut -d : -d '"' -f 4) || error "Failed to grep the release tag. Response from GitHub: ${ACC}${response}${NC}"
  print "Latest release tag: ${ACC}${releaseTag}${NC}"
fi

if ! [[ "$releaseTag" =~ ^v[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
  error "The specified release tag '${ACC}${releaseTag}${NC}' is not in the correct format"
fi

currentBundle=$(find . -mindepth 1 -maxdepth 1 -type d -regex '^.+-[0-9]+\.[0-9]+\.[0-9]+$' -print -quit)
if [[ -n "$currentBundle" ]]; then
  currentTag=$(echo "$currentBundle" | sed -E 's/.*([0-9]+\.[0-9]+\.[0-9]+)$/v\1/')
  if [[ "$currentTag" = "$releaseTag" ]]; then
    print --ok "Already Installed" "Release tag '${ACC}${releaseTag}${NC}' already installed"
    exit 0
  else
    print "Current release tag: '${ACC}${currentTag}${NC}'"
  fi
fi

releaseArchive="${releaseTag}.tar.gz"
print "Downloading '${ACC}${releaseArchive}${NC}'"
curl -sSLO "https://github.com/Carve/qbittorrent-webui-cjratliff.com/archive/refs/tags/${releaseArchive}" || error "Failed to download release '${ACC}${releaseTag}${NC}'"

print "Unpacking '${ACC}${releaseArchive}${NC}'"
tar -xzf "${releaseArchive}" || error 'Failed to unpack the source archive'

if [[ -n "$currentBundle" ]]; then
  print "Removinf the old release"
  rm -rf "$currentBundle"
fi

currentBundle=$(find . -mindepth 1 -maxdepth 1 -type d -regex '^.+-[0-9]+\.[0-9]+\.[0-9]+$' -print -quit | sed 's/^\.\///')
if [[ -z "$currentBundle" ]]; then
  error "Extracted files not found"
fi

print "Setting permissions for extracted files"
chmod -R g-w,o-rwx "$currentBundle"

print "Removing downloaded archive"
rm "${releaseArchive}"

currentBundle="/config/$currentBundle"
print "Changing configured theme to '${ACC}${currentBundle}${NC}'"
sed -i "s|^\\(WebUI\\\\RootFolder=\\).*\$|\\1${currentBundle}|" './qBittorrent/config/qBittorrent.conf' \
  || print --warn 'Warning' "Failed to change the configured theme to the new version. Manually set the theme to '${ACC}${currentBundle}${NC}'"

print --ok 'Done' "Successfully updated to '${ACC}${releaseTag}${NC}'"