Got it—let’s design a simple, scalable system for sharing pictures with friends using AWS. I’ll focus on a pragmatic architecture that’s reliable, secure, and easy to expand.
1. Core Requirements
- Users can upload photos.
- Users can view photos shared with them.
- Photos must be stored durably.
- Users need authentication.
- Optional: thumbnails, search, or tags.
2. High-Level Architecture
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[User Browser/App] | [CloudFront CDN] | [API Gateway / Load Balancer] | [Lambda / ECS / EC2] <-- Application Server | [S3 Bucket] <-- Photo storage | [DynamoDB / RDS] <-- Metadata (user, photo info)
3. Component Details
a) Storage
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S3 buckets for photos:
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s3://myapp-photos-original -
s3://myapp-photos-thumbnails -
Enable versioning and lifecycle rules to manage old files.
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Use S3 presigned URLs for secure upload/download directly from the client (reduces load on your backend).
b) Backend
- Options: Lambda (serverless, scalable) or ECS/Fargate if you need more control.
- Handles:
- User authentication.
- Access control.
- Generating presigned URLs for uploads/downloads.
- Metadata updates in database.
c) Metadata
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DynamoDB (NoSQL) or Aurora/MySQL (SQL):
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Table columns:
photo_id,user_id,s3_key,visibility(private/friends),timestamp,tags. -
Optional indexing for search/filtering.
d) Authentication
- Cognito User Pools for sign-up/sign-in.
- Integrate with API Gateway for authorized requests.
- Optional: Social logins (Google, Facebook).
e) Delivery
- CloudFront for global caching of photos.
- Thumbnails for previews.
- Use Lambda@Edge if you want transformations on the fly (resize, watermark).
f) Optional Features
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Image processing:
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Use Lambda triggered by S3 upload to generate thumbnails or compressed versions.
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Notifications:
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SNS/SQS to notify friends when new photos are uploaded.
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Search & Filtering:
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DynamoDB queries or Elasticsearch/OpenSearch for tags.
4. Workflow Example
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User logs in via Cognito.
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User uploads photo:
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Backend requests a presigned URL from S3.
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Frontend uploads directly to S3.
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S3 triggers Lambda to:
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Generate thumbnails.
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Store metadata in DynamoDB.
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Friends fetch a list of photos:
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Backend queries DynamoDB for visible photos.
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Returns S3 presigned URLs for download.
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CloudFront serves images for fast global delivery.
5. Security Considerations
- S3 buckets private by default.
- Use IAM roles and policies for Lambda/ECS to access S3.
- Ensure presigned URLs expire quickly.
- Use HTTPS everywhere (CloudFront + API Gateway).
6. Cost Efficiency
- Lambda + S3 + CloudFront is mostly pay-per-use → good for small/medium traffic.
- DynamoDB with on-demand mode avoids provisioning for unpredictable load.