S3 as Database

🧾 1. What is S3?

Amazon S3 is an object storage service that offers:

• Scalability: Store unlimited data

• Durability: 99.999999999% (11 9’s)

• Availability: 99.99%

• Access control, encryption, versioning, lifecycle rules, etc.

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🧱 2. Core Concepts

Concept	Description
Bucket	Top-level container for objects
Object	File + metadata
Key	Unique identifier of object (like filepath)
Prefix	Virtual folder path (e.g., images/2024/file.png)
Region	Bucket lives in a single AWS region

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🔒 3. Access Control Options

Method	Purpose
Bucket Policies	JSON policies for entire bucket
IAM Policies	Identity-based access
ACLs (legacy)	Object-level permissions
Block Public Access	Global safety toggle (enabled by default)

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🔁 4. Versioning

• Enable to keep all versions of an object (helps with recovery).

• Cannot be disabled, only suspended.

• Works well with MFA Delete for extra security.

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🧯 5. Lifecycle Rules

Automate transitions and deletions:

Transition	Example
S3 → Glacier	After 30 days (archival)
S3 → Delete	After 365 days
Noncurrent version → Delete	After 90 days

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🔐 6. Encryption Options

Method	Description
SSE-S3	Server-side AES-256 (default)
SSE-KMS	Server-side with AWS KMS (auditable)
SSE-C	Customer-provided keys
Client-side	Encrypt before uploading (you manage it)

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🌐 7. Static Website Hosting

• Enable "Static website hosting" in bucket settings

• Upload index.html, error.html

• Make objects public (with policy)

• Use S3 URL or attach Route53/CloudFront

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📥 8. Presigned URLs

• Temporarily allow uploads/downloads

• Valid for specific time (e.g., 10 mins)

• Use SDKs or CLI to generate

✅ Example (Boto3):

url = s3.generate_presigned_url(
    'get_object',
    Params={'Bucket': 'my-bucket', 'Key': 'file.txt'},
    ExpiresIn=600
)

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📊 9. Monitoring Tools

Tool	Purpose
CloudTrail	Track access requests
CloudWatch	S3 request metrics, errors
S3 Access Logs	Detailed access logs
AWS Config	Compliance auditing

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💸 10. Pricing Components

Metric	Pricing Basis
Storage	GB/month per storage class
Requests	PUT/GET/DELETE costs vary
Data transfer	Outbound to Internet costs
Lifecycle	Transitioning also costs

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📂 11. Storage Classes

Class	Use Case	Durability	Availability	Notes
Standard	General purpose	11 9's	99.99%	Default
Intelligent-Tiering	Auto-cost optimization	11 9's	99.9–99.99%	Great for unpredictable workloads
Standard-IA	Infrequent Access	11 9's	99.9%	Cheaper, but retrieval fee
Glacier	Archival	11 9's	Variable	Retrieval: minutes to hours
Glacier Deep Archive	Long-term archiving	11 9's	Variable	Cheapest, slowest retrieval

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🧪 12. Common CLI Commands

# Create bucket
aws s3 mb s3://my-bucket --region us-east-1

# Upload file
aws s3 cp file.txt s3://my-bucket/

# Sync local folder
aws s3 sync ./local-folder/ s3://my-bucket/

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

# Set public read
aws s3api put-bucket-policy --bucket my-bucket --policy file://policy.json

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📐 13. Terraform Example

resource "aws_s3_bucket" "example" {
  bucket = "my-tf-bucket"
  acl    = "private"

  versioning {
    enabled = true
  }

  lifecycle_rule {
    id      = "expire-old-versions"
    enabled = true

    noncurrent_version_expiration {
      days = 30
    }
  }

  tags = {
    Name        = "My bucket"
    Environment = "Dev"
  }
}

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💡 14. Best Practices

✅ Enable versioning
✅ Use SSE-KMS for encryption
✅ Use Block Public Access by default
✅ Tag buckets for billing
✅ Set lifecycle rules to control costs
✅ Use CloudFront + S3 for CDN use case
✅ Avoid hardcoding access — use IAM roles

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🧠 15. S3 vs EBS vs EFS

Feature	S3	EBS	EFS
Type	Object store	Block storage	File system
Access Method	HTTP(S)	EC2 mount	NFS mount
Use Case	Backup, archive, CDN	OS, DB storage	Shared web files
Max Size	Unlimited	Up to 16 TB	Unlimited
Multi-AZ	Yes (by design)	No (except io2)	Yes

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