Why managed services
CloudFront, API Gateway, Lambda, and S3 avoid long-running capacity for a bursty workload.
A secure serverless contact workflow for a major fast-food brand.
Case file / AWS serverless
A focused AWS workflow protects public submissions, validates image attachments, stores them privately, delivers email, and keeps failures visible to operators.
Project snapshot
- Client
- Major fast-food brand
- Workload
- Public customer-contact workflow
- Entry path
- CloudFront and AWS WAF
- Processing
- API Gateway and Lambda
- Attachments
- Validated images in private S3 storage
- Operations
- CloudWatch alerts to Slack and Microsoft Teams
The challenge
A public contact workflow without another always-on application service.
The workload was narrow, but public exposure made availability, abuse controls, attachment safety, and operator signals essential.
- Keep the public form available without another application service.
- Validate internet-facing submissions before support receives them.
- Accept image evidence without an open upload surface.
- Route runtime and delivery failures to existing operations channels.
Architecture note
A small serverless system with explicit public, processing, storage, and operations paths.
The drawing keeps the real AWS services visible; the notes explain the decisions around them.
Detailed system drawing
Customer contact and attachment workflow
Why private attachment storage
The handler checks image type and size before writing to private S3 storage.
Where validation happens
WAF and throttling protect the edge; Lambda validates content, attachments, and routing.
What operators can see
CloudWatch covers runtime, API, WAF, attachment, and email-delivery failures.
What remains client-owned
Infrastructure code, AWS resources, controls, alerts, and operating notes stay with the client.
Security and operations
Controls before, during, and after submission processing.
Controlled public entry
CloudFront, WAF, and API throttling protect the request path.
Backend validation
Lambda sanitises fields, checks attachments, and controls recipients.
Attachment boundary
Validated images move into private S3 storage.
Secrets and identity
Managed secrets and scoped IAM limit service access.
Email delivery
Transactional email uses controlled sending-domain configuration.
Visible failure path
CloudWatch routes failures to Slack and Microsoft Teams.
Results
Less infrastructure weight, with the failure path still visible.
Design risks avoided
The architecture avoids an open upload surface, hidden delivery failures, and an always-on server estate for a focused workload.
After handover
- No always-on application server for this workload.
- Edge protection, throttling, and backend validation.
- Private storage and explicit attachment checks.
- CloudWatch and team-channel failure alerts.
- Reviewable infrastructure changes through code.
Ownership after handover
The workflow, safeguards, and operating evidence stay inside your AWS environment.
Your team keeps the infrastructure code, security controls, dashboards, alerts, and runbooks.
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