S3 Operations

You are an AWS developer setting up S3 bucket operations. The user wants to upload files, download files, and generate presigned URLs for temporary access.

What to check first

• Run aws configure to verify AWS credentials are set (Access Key ID, Secret Access Key, region)
• Run aws s3 ls to confirm S3 bucket access and list available buckets
• Verify the bucket name and region match your AWS account setup

Steps

1. Install boto3 using pip install boto3 — this is the official AWS SDK for Python
2. Create an S3 client with boto3.client('s3') specifying your region
3. For uploads, use put_object() method with Bucket, Key, and Body parameters
4. For downloads, use get_object() method and read the StreamingBody response
5. For presigned URLs, use generate_presigned_url() with ClientMethod, Params, and ExpiresIn (seconds)
6. Set ExpiresIn to control URL expiration time (3600 = 1 hour, 86400 = 1 day)
7. Handle exceptions like NoCredentialsError, ClientError, and FileNotFoundError
8. Test each operation with a small test file before scaling to production

Code

import boto3
from botocore.exceptions import ClientError, NoCredentialsError
import os

class S3Operations:
    def __init__(self, bucket_name, region_name='us-east-1'):
        """Initialize S3 client with bucket name and region"""
        try:
            self.s3_client = boto3.client('s3', region_name=region_name)
            self.bucket_name = bucket_name
        except NoCredentialsError:
            print("ERROR: AWS credentials not configured")
            raise

    def upload_file(self, file_path, s3_key=None):
        """Upload file to S3 bucket"""
        if not os.path.exists(file_path):
            raise FileNotFoundError(f"File {file_path} not found")
        
        s3_key = s3_key or os.path.basename(file_path)
        
        try:
            self.s3_client.put_object(
                Bucket=self.bucket_name,
                Key=s3_key,
                Body=open(file_path, 'rb')
            )
            print(f"✓ Uploaded {file_path} to s3://{self.bucket_name}/{s3_key}")
            return f"s3://{self.bucket_name}/{s3_key}"
        except ClientError as e:
            print(f"ERROR uploading file: {e}")
            raise

    def download_file(self, s3_key, local_path):
        """Download file from S3 bucket"""
        try:
            response = self.s3_client.get_object(

Note: this example was truncated in the source. See the GitHub repo for the latest full version.

Common Pitfalls

• Treating this skill as a one-shot solution — most workflows need iteration and verification
• Skipping the verification steps — you don't know it worked until you measure
• Applying this skill without understanding the underlying problem — read the related docs first

When NOT to Use This Skill

• When a simpler manual approach would take less than 10 minutes
• On critical production systems without testing in staging first
• When you don't have permission or authorization to make these changes

How to Verify It Worked

• Run the verification steps documented above
• Compare the output against your expected baseline
• Check logs for any warnings or errors — silent failures are the worst kind

Production Considerations

• Test in staging before deploying to production
• Have a rollback plan — every change should be reversible
• Monitor the affected systems for at least 24 hours after the change