#!/bin/bash
#
# Docker Volume Backup Script
#
# This script is designed to back up Docker volumes to a specified directory. 
# It checks if each volume is empty before attempting to back it up and creates 
# compressed .tar.bz2 backup files for non-empty volumes.
#
#  Prerequisites
#
#    Docker: Ensure Docker is installed and running on your system.
#    Bash: This script is written in Bash and should be run in a Bash-compatible shell.
#    Backup Directory: Ensure the backup directory specified in the script exists or is writable.
#
#Script Overview
#
#The script performs the following tasks:
#
#    Defines Variables:
#        BACKUP_DIR: The directory where backup files will be stored.
#        TIMESTAMP: A timestamp used to uniquely identify backup files.
#        VOLUMES: An array of Docker volume names to back up.
#
#    Checks for Empty Volumes:
#        The script uses a temporary Docker container to check if a volume is empty. If a volume is empty, it skips the backup for that volume.
#
#    Backs Up Volumes:
#        For each non-empty volume, the script creates a compressed .tar.bz2 backup file in the specified backup directory.
#        The backup is performed using the loomchild/volume-backup Docker image.
#
#    Verifies Backup Success:
#        After each backup, the script checks if the backup was successful. If any backup fails, the script exits with an error.
#
#    Outputs Status:
#        The script provides status messages for each step, including skipped volumes, successful backups, and any errors encountered.
#
#    WARNING:
#	verify assigned values for these variables before proceeding:
#
#           BACKUP_DIR - verify the location is accessible. The mount point is named by the login user so it may look different 
#           VOLUMES    - are all the volumes to backup include in the list? 
#                        <volume>_nc6_files: stores the core admin account and binaries, config of next cloud
#                        <volume>_oo_data: document server
#                        <volume>_es_index: elastic search index files 
#                        <volume>_db: mariadb - nextcloud db 
#                        <volume>_clamav: antivirus defintions          
#
#
# Variables
BACKUP_DIR="/media/yazoo/nextcloud_files/backup/nc2/docker_volumes"  # Change this to your desired backup directory
#BACKUP_DIR="/media/yazoo/wdcrypt/2025-docker-data-migration/temp-nc6-backup"  # Change this to your desired backup directory
TIMESTAMP=$(date +"%Y%m%d_%H%M%S")

# List of volumes to backup
VOLUMES=("nc6_files" "nc6_oo_data" "nc6_es_index" "nc6_db" "nc6_clamav")  # Replace with your volume names
#VOLUMES=("nc6_redis" "nc6_oo_data" "nc6_es_index"  "nc6_clamav")  # Replace with your volume names

# Ensure backup directory exists
mkdir -p "$BACKUP_DIR"

# Function to check if a volume is empty
is_volume_empty() {
  local volume_name=$1

  # Use a temporary container to check if the volume is empty
  if docker run --rm -v "$volume_name:/volume" alpine sh -c '[ -z "$(ls -A /volume)" ]'; then
    return 0  # Volume is empty
  else
    return 1  # Volume is not empty
  fi
}



# Loop through each volume and perform the backup
for volume in "${VOLUMES[@]}"; do

  # Check if the volume is empty
  if is_volume_empty "$volume"; then
    echo "Skipping empty volume: $volume"
    continue
  fi


  # Define the backup file name
  
  BACKUP_FILE="$BACKUP_DIR/${volume}_backup-${TIMESTAMP}.tar.bz2"
  # Create a temporary container to backup the volume
  echo "Backing up volume: $volume to $BACKUP_FILE"
  # docker run --rm \
  #  -v "$BACKUP_DIR:/backup" \
  #  -v "$volume:/volume" \
  #  alpine tar czf "/backup/${volume}_backup_${sequence}_${TIMESTAMP}.tar.bz2" -C / volume
  docker run -v "$volume:/volume" -v "$BACKUP_DIR:/backup" --rm loomchild/volume-backup  backup -v ${volume}_backup-${TIMESTAMP} 



  # Check if the backup was successful
  if [ $? -eq 0 ]; then
    echo "Backup completed successfully: $BACKUP_FILE"
  else
    echo "Backup failed for volume: $volume!"
    exit 1
  fi
done

echo "All backups completed successfully!"