s3

# AWS S3

Amazon Simple Storage Service (S3) provides scalable object storage with industry-leading durability (99.999999999%). S3 is fundamental to AWS—used for data lakes, backups, static websites, and as storage for many other AWS services.

## Table of Contents

- [Core Concepts](#core-concepts)
- [Common Patterns](#common-patterns)
- [CLI Reference](#cli-reference)
- [Best Practices](#best-practices)
- [Troubleshooting](#troubleshooting)
- [References](#references)

## Core Concepts

### Buckets

Containers for objects. Bucket names are globally unique across all AWS accounts.

### Objects

Files stored in S3, consisting of data, metadata, and a unique key (path). Maximum size: 5 TB.

### Storage Classes

| Class | Use Case | Durability | Availability |
|-------|----------|------------|--------------|
| Standard | Frequently accessed | 99.999999999% | 99.99% |
| Intelligent-Tiering | Unknown access patterns | 99.999999999% | 99.9% |
| Standard-IA | Infrequent access | 99.999999999% | 99.9% |
| Glacier Instant | Archive with instant retrieval | 99.999999999% | 99.9% |
| Glacier Flexible | Archive (minutes to hours) | 99.999999999% | 99.99% |
| Glacier Deep Archive | Long-term archive | 99.999999999% | 99.99% |

### Versioning

Keeps multiple versions of an object. Essential for data protection and recovery.

## Common Patterns

### Create a Bucket with Best Practices

**AWS CLI:**

```bash
# Create bucket (us-east-1 doesn't need LocationConstraint)
aws s3api create-bucket \
  --bucket my-secure-bucket-12345 \
  --region us-west-2 \
  --create-bucket-configuration LocationConstraint=us-west-2

# Enable versioning
aws s3api put-bucket-versioning \
  --bucket my-secure-bucket-12345 \
  --versioning-configuration Status=Enabled

# Block public access
aws s3api put-public-access-block \
  --bucket my-secure-bucket-12345 \
  --public-access-block-configuration \
    BlockPublicAcls=true,IgnorePublicAcls=true,BlockPublicPolicy=true,RestrictPublicBuckets=true

# Enable encryption
aws s3api put-bucket-encryption \
  --bucket my-secure-bucket-12345 \
  --server-side-encryption-configuration '{
    "Rules": [{"ApplyServerSideEncryptionByDefault": {"SSEAlgorithm": "AES256"}}]
  }'
```

**boto3:**

```python
import boto3

s3 = boto3.client('s3', region_name='us-west-2')

# Create bucket
s3.create_bucket(
    Bucket='my-secure-bucket-12345',
    CreateBucketConfiguration={'LocationConstraint': 'us-west-2'}
)

# Enable versioning
s3.put_bucket_versioning(
    Bucket='my-secure-bucket-12345',
    VersioningConfiguration={'Status': 'Enabled'}
)

# Block public access
s3.put_public_access_block(
    Bucket='my-secure-bucket-12345',
    PublicAccessBlockConfiguration={
        'BlockPublicAcls': True,
        'IgnorePublicAcls': True,
        'BlockPublicPolicy': True,
        'RestrictPublicBuckets': True
    }
)
```

### Upload and Download Objects

```bash
# Upload a single file
aws s3 cp myfile.txt s3://my-bucket/path/myfile.txt

# Upload with metadata
aws s3 cp myfile.txt s3://my-bucket/path/myfile.txt \
  --metadata "environment=production,version=1.0"

# Download a file
aws s3 cp s3://my-bucket/path/myfile.txt ./myfile.txt

# Sync a directory
aws s3 sync ./local-folder s3://my-bucket/prefix/ --delete

# Copy between buckets
aws s3 cp s3://source-bucket/file.txt s3://dest-bucket/file.txt
```

### Generate Presigned URL

```python
import boto3
from botocore.config import Config

s3 = boto3.client('s3', config=Config(signature_version='s3v4'))

# Generate presigned URL for download (GET)
url = s3.generate_presigned_url(
    'get_object',
    Params={'Bucket': 'my-bucket', 'Key': 'path/to/file.txt'},
    ExpiresIn=3600  # URL valid for 1 hour
)

# Generate presigned URL for upload (PUT)
upload_url = s3.generate_presigned_url(
    'put_object',
    Params={
        'Bucket': 'my-bucket',
        'Key': 'uploads/newfile.txt',
        'ContentType': 'text/plain'
    },
    ExpiresIn=3600
)
```

### Configure Lifecycle Policy

```bash
cat > lifecycle.json << 'EOF'
{
  "Rules": [
    {
      "ID": "MoveToGlacierAfter90Days",
      "Status": "Enabled",
      "Filter": {"Prefix": "logs/"},
      "Transitions": [
        {"Days": 90, "StorageClass": "GLACIER"}
      ],
      "Expiration": {"Days": 365}
    },
    {
      "ID": "DeleteOldVersions",
      "Status": "Enabled",
      "Filter": {},
      "NoncurrentVersionExpiration": {"NoncurrentDays": 30}
    }
  ]
}
EOF

aws s3api put-bucket-lifecycle-configuration \
  --bucket my-bucket \
  --lifecycle-configuration file://lifecycle.json
```

### Event Notifications to Lambda

```bash
aws s3api put-bucket-notification-configuration \
  --bucket my-bucket \
  --notification-configuration '{
    "LambdaFunctionConfigurations": [
      {
        "LambdaFunctionArn": "arn:aws:lambda:us-east-1:123456789012:function:ProcessS3Upload",
        "Events": ["s3:ObjectCreated:*"],
        "Filter": {
          "Key": {
            "FilterRules": [
              {"Name": "prefix", "Value": "uploads/"},
              {"Name": "suffix", "Value": ".jpg"}
            ]
          }
        }
      }
    ]
  }'
```

## CLI Reference

### High-Level Commands (aws s3)

| Command | Description |
|---------|-------------|
| `aws s3 ls` | List buckets or objects |
| `aws s3 cp` | Copy files |
| `aws s3 mv` | Move files |
| `aws s3 rm` | Delete files |
| `aws s3 sync` | Sync directories |
| `aws s3 mb` | Make bucket |
| `aws s3 rb` | Remove bucket |

### Low-Level Commands (aws s3api)

| Command | Description |
|---------|-------------|
| `aws s3api create-bucket` | Create bucket with options |
| `aws s3api put-object` | Upload with full control |
| `aws s3api get-object` | Download with options |
| `aws s3api delete-object` | Delete single object |
| `aws s3api put-bucket-policy` | Set bucket policy |
| `aws s3api put-bucket-versioning` | Enable versioning |
| `aws s3api list-object-versions` | List all versions |

### Useful Flags

- `--recursive`: Process all objects in prefix
-