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Backup_scripts

Chapter 37: Backup and Restore Scripts

Section titled “Chapter 37: Backup and Restore Scripts”

Overview

Section titled “Overview”

This chapter covers comprehensive backup and restore scripts for databases, files, and entire systems. These scripts are essential for disaster recovery and data protection.

Database Backup Scripts

Section titled “Database Backup Scripts”

MySQL/MariaDB Backup

Section titled “MySQL/MariaDB Backup”
#!/usr/bin/env bash
# backup_mysql.sh - Backup MySQL/MariaDB databases


set -euo pipefail


# Configuration
DB_HOST="${DB_HOST:-localhost}"
DB_USER="${DB_USER:-root}"
DB_PASSWORD="${DB_PASSWORD:-}"
BACKUP_DIR="${BACKUP_DIR:-/backups/mysql}"
RETENTION_DAYS="${RETENTION_DAYS:-30}"
COMPRESSION="${COMPRESSION:-gzip}"


log() { echo "[$(date '+%Y-%m-%d %H:%M:%S')] $*"; }


error() { echo "[$(date '+%Y-%m-%d %H:%M:%S')] ERROR: $*" >&2; exit 1; }


# Validate configuration
: "${DB_PASSWORD:?DB_PASSWORD environment variable required}"


# Create backup directory
mkdir -p "$BACKUP_DIR"


# Get list of databases
get_databases() {
    if [[ "$DB_PASSWORD" == "" ]]; then
        mysql -h "$DB_HOST" -u "$DB_USER" -e "SHOW DATABASES;" | grep -v Database
    else
        mysql -h "$DB_HOST" -u "$DB_USER" -p"$DB_PASSWORD" -e "SHOW DATABASES;" | grep -v Database
    fi
}


# Backup single database
backup_database() {
    local db_name="$1"
    local timestamp
    timestamp=$(date +%Y%m%d_%H%M%S)
    local backup_file="${BACKUP_DIR}/${db_name}_${timestamp}.sql"


    log "Backing up database: $db_name"


    if [[ "$DB_PASSWORD" == "" ]]; then
        mysqldump -h "$DB_HOST" -u "$DB_USER" \
            --single-transaction \
            --quick \
            --lock-tables=false \
            "$db_name" > "$backup_file"
    else
        mysqldump -h "$DB_HOST" -u "$DB_USER" -p"$DB_PASSWORD" \
            --single-transaction \
            --quick \
            --lock-tables=false \
            "$db_name" > "$backup_file"
    fi


    # Compress if enabled
    if [[ "$COMPRESSION" == "gzip" ]]; then
        gzip "$backup_file"
        backup_file="${backup_file}.gz"
    fi


    log "Backup created: $backup_file"
}


# Cleanup old backups
cleanup_old_backups() {
    log "Cleaning up backups older than $RETENTION_DAYS days..."


    find "$BACKUP_DIR" -name "*.sql*" -mtime +$RETENTION_DAYS -delete


    log "Cleanup complete"
}


# Main
main() {
    log "Starting MySQL backup..."


    # Backup all databases
    while read -r db; do
        # Skip system databases
        [[ "$db" == "information_schema" ]] && continue
        [[ "$db" == "performance_schema" ]] && continue
        [[ "$db" == "mysql" ]] && continue


        backup_database "$db"
    done < <(get_databases)


    # Cleanup
    cleanup_old_backups


    log "MySQL backup complete"
}


main

PostgreSQL Backup

Section titled “PostgreSQL Backup”
#!/usr/bin/env bash
# backup_postgres.sh - Backup PostgreSQL databases


set -euo pipefail


# Configuration
DB_HOST="${DB_HOST:-localhost}"
DB_USER="${DB_USER:-postgres}"
DB_PORT="${DB_PORT:-5432}"
BACKUP_DIR="${BACKUP_DIR:-/backups/postgres}"
RETENTION_DAYS="${RETENTION_DAYS:-30}"


log() { echo "[$(date '+%Y-%m-%d %H:%M:%S')] $*"; }


# Create backup directory
mkdir -p "$BACKUP_DIR"


# Get list of databases
get_databases() {
    psql -h "$DB_HOST" -U "$DB_USER" -p "$DB_PORT" -t -c "SELECT datname FROM pg_database WHERE datistemplate = false;"
}


# Backup single database
backup_database() {
    local db_name="$1"
    local timestamp
    timestamp=$(date +%Y%m%d_%H%M%S)
    local backup_file="${BACKUP_DIR}/${db_name}_${timestamp}.sql"


    log "Backing up database: $db_name"


    PGPASSWORD="$DB_PASSWORD" pg_dump -h "$DB_HOST" -U "$DB_USER" -p "$DB_PORT" \
        -Fc \
        "$db_name" > "$backup_file"


    log "Backup created: $backup_file"
}


# Main
main() {
    log "Starting PostgreSQL backup..."


    while read -r db; do
        db=$(echo "$db" | xargs)
        [[ -z "$db" ]] && continue
        backup_database "$db"
    done < <(get_databases)


    log "PostgreSQL backup complete"
}


main

File Backup Scripts

Section titled “File Backup Scripts”

Incremental Backup with rsync

Section titled “Incremental Backup with rsync”
#!/usr/bin/env bash
# backup_incremental.sh - Incremental file backup


set -euo pipefail


# Configuration
SOURCE_DIR="${1:-/data}"
BACKUP_DIR="${2:-/backups}"
EXCLUDE_FILE="${EXCLUDE_FILE:-/etc/backup/exclude.txt}"


log() { echo "[$(date '+%Y-%m-%d %H:%M:%S')] $*"; }


# Create timestamped backup directory
timestamp=$(date +%Y%m%d_%H%M%S)
current_backup="$BACKUP_DIR/current"
new_backup="$BACKUP_DIR/backup_$timestamp"


log "Starting incremental backup..."


# Create hard-link based incremental backup
# This saves space by using hard links for unchanged files


if [[ -d "$current_backup" ]]; then
    # Use rsync with link-dest for incremental backup
    rsync -avh \
        --delete \
        --delete-excluded \
        --link-dest="$current_backup" \
        $([[ -f "$EXCLUDE_FILE" ]] && echo "--exclude-from=$EXCLUDE_FILE") \
        "$SOURCE_DIR/" "$new_backup/"


    # Remove old current and link new backup
    rm -rf "$current_backup"
    ln -s "$new_backup" "$current_backup"
else
    # First backup - full backup
    rsync -avh \
        --delete \
        --delete-excluded \
        $([[ -f "$EXCLUDE_FILE" ]] && echo "--exclude-from=$EXCLUDE_FILE") \
        "$SOURCE_DIR/" "$new_backup/"


    ln -s "$new_backup" "$current_backup"
fi


log "Backup complete: $new_backup"
log "Current symlink updated to: $current_backup"

Encrypted Backup

Section titled “Encrypted Backup”
#!/usr/bin/env bash
# backup_encrypted.sh - Encrypted file backup


set -euo pipefail


# Configuration
SOURCE_DIR="${1:-/data}"
BACKUP_DIR="${2:-/backups/encrypted}"
ENCRYPTION_KEY="${ENCRYPTION_KEY:-}"
PASSPHRASE="${PASSPHRASE:-}"


log() { echo "[$(date '+%Y-%m-%d %H:%M:%S')] $*"; }


# Validate encryption key
: "${ENCRYPTION_KEY:?ENCRYPTION_KEY environment variable required}"


# Create backup directory
mkdir -p "$BACKUP_DIR"


# Create backup filename
timestamp=$(date +%Y%m%d_%H%M%S)
backup_file="$BACKUP_DIR/backup_${timestamp}.tar.gz.gpg"


log "Creating encrypted backup..."


# Create compressed archive and encrypt
tar -czf - -C "$(dirname "$SOURCE_DIR")" "$(basename "$SOURCE_DIR")" | \
    gpg --symmetric \
        --batch \
        --passphrase "$ENCRYPTION_KEY" \
        --cipher-algo AES256 \
        --compress-algo none \
        -o "$backup_file"


log "Encrypted backup created: $backup_file"
log "Backup size: $(du -h "$backup_file" | cut -f1)"

Restore Scripts

Section titled “Restore Scripts”

Database Restore

Section titled “Database Restore”
#!/usr/bin/env bash
# restore_mysql.sh - Restore MySQL database


set -euo pipefail


# Configuration
DB_HOST="${DB_HOST:-localhost}"
DB_USER="${DB_USER:-root}"
DB_PASSWORD="${DB_PASSWORD:-}"
BACKUP_FILE="${1:-}"
TARGET_DB="${2:-}"


log() { echo "[$(date '+%Y-%m-%d %H:%M:%S')] $*"; }


error() { echo "[$(date '+%Y-%m-%d %H:%M:%S')] ERROR: $*" >&2; exit 1; }


# Validate
[[ -z "$BACKUP_FILE" ]] && error "Usage: $0 <backup_file> [target_database]"
[[ -f "$BACKUP_FILE" ]] || error "Backup file not found: $BACKUP_FILE"
: "${DB_PASSWORD:?DB_PASSWORD environment variable required}"


# Determine if compressed
if [[ "$BACKUP_FILE" == *.gz ]]; then
    DECOMPRESS="zcat"
else
    DECOMPRESS="cat"
fi


log "Restoring database from: $BACKUP_FILE"


# Restore database
if [[ -n "$TARGET_DB" ]]; then
    log "Restoring to database: $TARGET_DB"
    $DECOMPRESS "$BACKUP_FILE" | \
        mysql -h "$DB_HOST" -u "$DB_USER" -p"$DB_PASSWORD" "$TARGET_DB"
else
    # Extract database name from filename
    db_name=$(basename "$BACKUP_FILE" | sed 's/_[0-9].*//')
    log "Restoring to database: $db_name"
    $DECOMPRESS "$BACKUP_FILE" | \
        mysql -h "$DB_HOST" -u "$DB_USER" -p"$DB_PASSWORD"
fi


log "Restore complete"

Backup Verification

Section titled “Backup Verification”

Verify Backup Integrity

Section titled “Verify Backup Integrity”
#!/usr/bin/env bash
# verify_backup.sh - Verify backup integrity


set -euo pipefail


BACKUP_FILE="${1:-}"


log() { echo "[$(date '+%Y-%m-%d %H:%M:%S')] $*"; }
error() { echo "[$(date '+%Y-%m-%d %H:%M:%S')] ERROR: $*" >&2; exit 1; }


[[ -z "$BACKUP_FILE" ]] && error "Usage: $0 <backup_file>"
[[ -f "$BACKUP_FILE" ]] || error "File not found: $BACKUP_FILE"


log "Verifying backup: $BACKUP_FILE"


# Check file exists and is readable
if [[ -r "$BACKUP_FILE" ]]; then
    log "✓ File is readable"
else
    error "✗ File is not readable"
fi


# Check file is not empty
if [[ -s "$BACKUP_FILE" ]]; then
    log "✓ File is not empty"
    log "  Size: $(du -h "$BACKUP_FILE" | cut -f1)"
else
    error "✗ File is empty"
fi


# Verify based on extension
case "$BACKUP_FILE" in
    *.tar.gz|*.tgz)
        log "Verifying tar.gz integrity..."
        if tar -tzf "$BACKUP_FILE" &>/dev/null; then
            log "✓ tar.gz integrity OK"
        else
            error "✗ tar.gz integrity check failed"
        fi
        ;;
    *.sql.gz)
        log "Verifying SQL backup..."
        if zcat "$BACKUP_FILE" | head -1 | grep -q "MySQL\|MariaDB"; then
            log "✓ SQL backup appears valid"
        fi
        ;;
    *.gpg)
        log "✓ GPG encrypted backup - cannot verify without key"
        ;;
esac


log "Verification complete"

Automated Backup Schedule

Section titled “Automated Backup Schedule”

Backup Rotation Script

Section titled “Backup Rotation Script”
#!/usr/bin/env bash
# backup_rotation.sh - Manage backup rotation


set -euo pipefail


BACKUP_DIR="${BACKUP_DIR:-/backups}"
DAILY_COUNT="${DAILY_COUNT:-7}"
WEEKLY_COUNT="${WEEKLY_COUNT:-4}"
MONTHLY_COUNT="${MONTHLY_COUNT:-12}"


log() { echo "[$(date '+%Y-%m-%d %H:%M:%S')] $*"; }


rotate_backups() {
    local pattern="$1"
    local keep_count="$2"


    log "Rotating backups matching: $pattern (keep $keep_count)"


    # List backups sorted by date
    local backups
    backups=($(ls -1t "$BACKUP_DIR"/$pattern 2>/dev/null))


    # Keep only the specified number
    if [[ ${#backups[@]} -gt $keep_count ]]; then
        for ((i=keep_count; i<${#backups[@]}; i++)); do
            log "Removing old backup: ${backups[$i]}"
            rm -f "${backups[$i]}"
        done
    fi


    log "Rotation complete"
}


main() {
    log "Starting backup rotation..."


    # Daily backups (keep 7)
    rotate_backups "*daily*" $DAILY_COUNT


    # Weekly backups (keep 4)
    rotate_backups "*weekly*" $WEEKLY_COUNT


    # Monthly backups (keep 12)
    rotate_backups "*monthly*" $MONTHLY_COUNT


    log "Backup rotation complete"
}


main

Summary

Section titled “Summary”

In this chapter, you learned:

  • ✅ MySQL/MariaDB backup scripts
  • ✅ PostgreSQL backup scripts
  • ✅ Incremental backup with rsync
  • ✅ Encrypted backups
  • ✅ Database restore scripts
  • ✅ Backup verification
  • ✅ Backup rotation management
  • ✅ Automated backup scheduling

Next Steps

Section titled “Next Steps”

Continue to the next chapter to learn about Log Analysis Scripts.

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