Daily Hack #day85 - Redis Backup and Recovery

The shell script below automates the backup and recovery process for a Redis database. This script will create a backup of the Redis database and allow you to restore it from the backup.

Redis Backup and Recovery Script

#!/bin/bash

# Configuration
REDIS_CLI="/usr/bin/redis-cli"
BACKUP_DIR="/var/backups/redis"
TIMESTAMP=$(date +'%Y%m%d%H%M%S')
BACKUP_FILE="$BACKUP_DIR/redis_backup_$TIMESTAMP.rdb"
LOG_FILE="/var/log/redis_backup_recovery.log"

# Function to log messages
log_message() {
    echo "$(date +'%Y-%m-%d %H:%M:%S') - $1" | tee -a $LOG_FILE
}

# Function to create a backup
backup_redis() {
    log_message "Starting Redis backup"

    # Create backup directory if it doesn't exist
    mkdir -p $BACKUP_DIR

    # Trigger Redis to create a backup
    $REDIS_CLI SAVE

    # Check if the SAVE command was successful
    if [ $? -ne 0 ]; then
        log_message "Failed to trigger Redis backup"
        exit 1
    fi

    # Copy the dump file to the backup directory with a timestamp
    cp /var/lib/redis/dump.rdb $BACKUP_FILE

    # Verify the backup file was created successfully
    if [ $? -eq 0 ]; then
        log_message "Redis backup created successfully at $BACKUP_FILE"
    else
        log_message "Failed to create Redis backup file"
        exit 1
    fi
}

# Function to restore from a backup
restore_redis() {
    BACKUP_TO_RESTORE=$1

    if [ ! -f $BACKUP_TO_RESTORE ]; then
        log_message "Backup file $BACKUP_TO_RESTORE does not exist"
        exit 1
    fi

    log_message "Starting Redis restore from $BACKUP_TO_RESTORE"

    # Stop Redis server
    systemctl stop redis

    # Check if the Redis server stopped successfully
    if [ $? -ne 0 ]; then
        log_message "Failed to stop Redis server"
        exit 1
    fi

    # Copy the backup file to the Redis data directory
    cp $BACKUP_TO_RESTORE /var/lib/redis/dump.rdb

    # Verify the backup file was copied successfully
    if [ $? -eq 0 ]; then
        log_message "Backup file copied to Redis data directory"
    else
        log_message "Failed to copy backup file"
        exit 1
    fi

    # Start Redis server
    systemctl start redis

    # Check if the Redis server started successfully
    if [ $? -eq 0 ]; then
        log_message "Redis restored successfully from $BACKUP_TO_RESTORE"
    else
        log_message "Failed to start Redis server"
        exit 1
    fi
}

# Main script logic
case $1 in
    backup)
        backup_redis
        ;;
    restore)
        if [ -z "$2" ]; then
            echo "Usage: $0 restore <backup_file>"
            exit 1
        fi
        restore_redis $2
        ;;
    *)
        echo "Usage: $0 {backup|restore <backup_file>}"
        exit 1
        ;;
esac

exit 0

Explaining the script steps

1. Configuration:

   • REDIS_CLI: Path to the redis-cli executable.

   • BACKUP_DIR: Directory where backups will be stored.

   • TIMESTAMP: Current timestamp to uniquely name backup files.

   • BACKUP_FILE: Full path to the backup file.

   • LOG_FILE: Log file to record backup and restore operations.

2. Logging Function:

   • log_message(): Logs messages with timestamps to the log file.

3. Backup Function:

   • backup_redis(): Creates a backup of the Redis database.

     • Triggers the Redis SAVE command to create a backup.

     • Copies the dump.rdb file to the backup directory with a timestamp.

4. Restore Function:

   • restore_redis(): Restores the Redis database from a specified backup file.

     • Stops the Redis server.

     • Copies the specified backup file to the Redis data directory.

     • Starts the Redis server.

5. Main Script Logic:

   • Uses a case statement to handle backup and restore commands.

   • backup: Calls the backup_redis function.

   • restore: Calls the restore_redis function with the specified backup file.

Usage

1. Make the script executable:

    chmod +x redis_backup_recovery.sh
   

2. Run the backup command:

    ./redis_backup_recovery.sh backup
   

3. Run the restore command:

    ./redis_backup_recovery.sh restore /path/to/backup_file
   

Scheduling with Cron

To automate the backup process, you can schedule the script using cron:

1. Edit the crontab:

    crontab -e
   

2. Add a cron job to run the script daily at 2 AM:

    0 2 * * * /path/to/redis_backup_recovery.sh backup
   

Make sure to replace /path/to/redis_backup_recovery.sh with the actual path to your script.

This script automates the process of backing up and restoring a Redis database, providing a reliable way to manage Redis data.