Automate Database Backup for Castopod with BASH

#!/bin/bash
# 
# caos30 & Claude AI - 2024-07-15
#
# - This script dumps the Castopod database
# - It also lets you specify how many backups to keep
# - So you can run it from your cron jobs
# - The DB connection is taken from the .env Castopod file

# Number of backups to keep
KEEP_BACKUPS=5

# Determine the script's directory
SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"

# Function to read variables from .env file
read_env() {
    ENV_FILE="${SCRIPT_DIR}/.env"
    if [ -f "$ENV_FILE" ]; then
        while IFS= read -r line || [[ -n "$line" ]]; do
            if [[ -z "$line" || "$line" == \#* ]]; then
                continue
            fi
            if [[ "$line" =~ ^([^=]+)=(.*)$ ]]; then
                key="${BASH_REMATCH[1]}"
                value="${BASH_REMATCH[2]}"
                value=$(echo "$value" | sed -e 's/^"//' -e 's/"$//')
                eval "${key//./_}='$value'"
            else
                echo "Warning: Malformed line in .env file: $line"
            fi
        done < "$ENV_FILE"
    else
        echo "The .env file does not exist in ${SCRIPT_DIR}"
        exit 1
    fi
}

# Read variables from .env file
read_env

# Assign variables
HOST="${database_default_hostname}"
DB="${database_default_database}"
USER="${database_default_username}"
PASS="${database_default_password}"
PREFIX="${database_default_DBPrefix}"

# Backup file name
BACKUP_FILE="${SCRIPT_DIR}/backup_$(date +%Y%m%d_%H%M%S).sql"
COMPRESSED_BACKUP_FILE="${BACKUP_FILE}.gz"

# Function to perform the backup
do_backup() {
    mysqldump --host="$HOST" --user="$USER" --password="$PASS" \
              --skip-lock-tables --no-tablespaces \
              "$DB" > "$BACKUP_FILE"
}

# Function to compress the backup
compress_backup() {
    gzip -f "$BACKUP_FILE"
}

# Function to cleanup old backups
cleanup_old_backups() {
    local backup_files=($(ls -t "${SCRIPT_DIR}"/backup_*.sql.gz 2>/dev/null))
    local count=${#backup_files[@]}

    if [ $count -gt $KEEP_BACKUPS ]; then
        echo "Cleaning up old backups..."
        for ((i=$KEEP_BACKUPS; i<$count; i++)); do
            echo "Removing old backup: ${backup_files[i]}"
            rm "${backup_files[i]}"
        done
    fi
}

# Change to the script's directory
cd "$SCRIPT_DIR"

# Cleanup old backups before creating a new one
cleanup_old_backups

# Perform the database dump
if do_backup; then
    echo "Backup created successfully: $BACKUP_FILE"
    
    # Compress the backup
    if compress_backup; then
        echo "Backup compressed successfully: $COMPRESSED_BACKUP_FILE"
        # Note: gzip has already removed the original file, so we don't need to do it manually
    else
        echo "Error compressing the backup."
        exit 1
    fi
else
    echo "Error performing database backup."
    exit 1
fi

# Final cleanup to ensure we don't exceed the limit
cleanup_old_backups

echo "Backup process completed."