Introduction

Data backup is a critical part of any IT infrastructure. Whether you are managing personal files, application data, or business documents, maintaining regular backups helps protect against accidental deletion, hardware failures, ransomware attacks, and other unexpected incidents.

Amazon S3 (Simple Storage Service) is a highly durable, secure, and scalable cloud storage service provided by Amazon Web Services (AWS). By storing backups in Amazon S3, organizations can ensure their data remains accessible and protected from local system failures.

In this tutorial, we will create a Python script that automatically uploads files from a local Windows folder to an Amazon S3 bucket. The script organizes backups into date-based folders, making it easy to manage historical backups and restore files when required. We will also discuss how to schedule the script to run automatically using Windows Task Scheduler.

Prerequisites

Before proceeding, ensure the following requirements are met:

1. Windows Machine

The script is designed to run on a Windows system.

2. Python Installation

Install Python 3 on your Windows machine and verify the installation:

python --version

3. AWS Account

You need an active AWS account with access to Amazon S3.

4. S3 Bucket

Create an S3 bucket where backups will be stored.

Example bucket:

my-backup-bucket

5. IAM User Credentials

Create an IAM user with the necessary S3 permissions and obtain:

  • AWS Access Key ID
  • AWS Secret Access Key

A sample IAM policy is shown below:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "s3:PutObject",
        "s3:GetObject",
        "s3:ListBucket"
      ],
      "Resource": [
        "arn:aws:s3:::my-backup-bucket",
        "arn:aws:s3:::my-backup-bucket/*"
      ]
    }
  ]
}

Install Required Python Package

Install the AWS SDK for Python (boto3):

pip install boto3

Verify installation:

pip show boto3

Create the Backup Script

Create a file named:

s3backup.py

Add the following code:

import boto3
import os
from datetime import datetime

# AWS Configuration
AWS_ACCESS_KEY_ID = "YOUR_ACCESS_KEY"
AWS_SECRET_ACCESS_KEY = "YOUR_SECRET_KEY"
AWS_REGION = "us-east-1"

# S3 Configuration
BUCKET_NAME = "my-backup-bucket"

# Local Folder to Backup
SOURCE_DIR = r"C:\backup"

# Create Date-Based Folder
date_folder = datetime.utcnow().strftime("%Y%m%d")

# Create S3 Client
s3 = boto3.client(
    "s3",
    aws_access_key_id=AWS_ACCESS_KEY_ID,
    aws_secret_access_key=AWS_SECRET_ACCESS_KEY,
    region_name=AWS_REGION
)

# Upload Files
for root, dirs, files in os.walk(SOURCE_DIR):
    for file in files:
        local_file = os.path.join(root, file)

        # Preserve Folder Structure
        relative_path = os.path.relpath(local_file, SOURCE_DIR)
        s3_key = f"{date_folder}/{relative_path.replace(os.sep, '/')}"

        print(f"Uploading {local_file}")

        try:
            s3.upload_file(local_file, BUCKET_NAME, s3_key)
            print(f"Uploaded to s3://{BUCKET_NAME}/{s3_key}")
        except Exception as e:
            print(f"Failed: {e}")

print("Backup completed successfully.")

How the Script Works

Step 1: Connect to AWS

The script creates a connection to Amazon S3 using your IAM credentials.

s3 = boto3.client(...)

Step 2: Generate a Date-Based Folder

The current date is generated in the format:

20260818

This helps organize backups by date.

date_folder = datetime.utcnow().strftime("%Y%m%d")

Step 3: Scan the Local Directory

The script recursively scans all files under:

C:\backup

using:

os.walk()

Step 4: Upload Files to S3

Each file is uploaded to the S3 bucket while maintaining the original folder structure.

Example:

C:\backup\documents\report.pdf

becomes:

s3://my-backup-bucket/20260818/documents/report.pdf

Running the Script

Execute the script from PowerShell:

python s3backup.py

Example output:

Uploading C:\backup\documents\report.pdf
Uploaded to s3://my-backup-bucket/20260818/documents/report.pdf

Uploading C:\backup\images\logo.png
Uploaded to s3://my-backup-bucket/20260818/images/logo.png

Backup completed successfully.

Verify Backup in Amazon S3

Log in to the AWS Management Console and navigate to:

Amazon S3 → Your Bucket

You should see a date-based folder:

20260818/

Inside the folder, all files and subdirectories from the source folder will be available.

Automating Daily Backups

Windows Task Scheduler can be used to automate the backup process.

Step 1: Open Task Scheduler

Press:

Windows + R

and run:

taskschd.msc

Step 2: Create a New Task

Select:

Create Basic Task

Step 3: Configure Trigger

Choose:

Daily

and specify the desired execution time.

Step 4: Configure Action

Program:

C:\Python312\python.exe

Arguments:

C:\scripts\s3backup.py

Step 5: Save the Task

The backup process will now execute automatically every day.

Best Practices

Use IAM Roles and Policies

Grant only the required permissions to the backup user.

Avoid Hardcoding Credentials

Instead of storing credentials in scripts, use:

AWS CLI Credentials File

or

IAM Roles

where possible.

Enable S3 Versioning

Versioning provides additional protection against accidental deletions and overwrites.

Use Lifecycle Policies

Configure lifecycle policies to move older backups to:

  • S3 Standard-IA
  • S3 Glacier
  • S3 Glacier Deep Archive

to reduce storage costs.

Enable Encryption

Use:

  • SSE-S3
  • SSE-KMS

to protect backup data.

Alternative Approach: AWS CLI

For simple backup requirements, AWS CLI can be used instead of Python.

Install AWS CLI:

aws configure

Sync a folder:

aws s3 sync C:\backup s3://my-backup-bucket/backup/

Create date-based backups:

$today = Get-Date -Format "yyyyMMdd"
aws s3 sync C:\backup s3://my-backup-bucket/$today/

AWS CLI is often the preferred choice for straightforward backup tasks because it is easy to configure and maintain.

Conclusion

Amazon S3 provides a secure, scalable, and cost-effective solution for storing backups in the cloud. By combining Python and the AWS SDK, you can automate the process of uploading files from a Windows machine to an S3 bucket while maintaining an organized backup structure based on dates.

This approach not only protects your data from local system failures but also simplifies backup management and recovery. For enterprise environments, additional features such as versioning, lifecycle policies, encryption, and automated scheduling can further enhance reliability and security. Whether you are backing up personal files or critical business data, Amazon S3 offers a dependable platform for long-term data protection and disaster recovery.

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