How This Was Built | Uptime Monitor

A serverless uptime monitoring solution designed for personal fleet management, demonstrating AWS proficiency and SRE principles through Go, Lambda, S3-backed persistence, and scheduled EventBridge triggers.

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Architecture Blueprint

┌───────────────────────┐ │ EventBridge │ └───────────┬───────────┘ │ (Hourly Trigger) ▼ ┌───────────────────────┐ Client ───►│ AWS Lambda │ (HTTP Req) │ (Go API Router) │ └────┬──────┬──────┬────┘ │ │ │ ┌──────────────┘ │ └──────────────┐ ▼ (/latest) ▼ (/check) ▼ (/history) ┌──────────┐ ┌───────────┐ ┌──────────┐ │ S3 Read │ │ Run check │ │ S3 Read │ │ latest │ │ against │ │ history │ │ .json │ │ websites │ │ .json │ └──────────┘ └─────┬─────┘ └──────────┘ │ (Write outputs) ▼ ┌───────────┐ │ S3 Bucket │ │ Store │ └───────────┘

Core Components & Logic

AWS Lambda Execution

AWS Lambda serves as the execution runtime, running a Go API router that handles HTTP endpoints and validates request actions.
Amazon S3 Storage

Stores state objects directly in Amazon S3, maintaining latest.json for current fleet status snapshots and history.json for rolling historical trend metrics.
EventBridge Cron Trigger

Invokes the Lambda cron path automatically every hour via Amazon EventBridge, driving background uptime checks to ensure persistent coverage.

Validation & Resiliency Testing

Reproducibility

Provisioned entirely using declarative Terraform modules, ensuring reproducible environment boots, IAM role boundary containment, and consistent AWS resource setups.

Automated Verification

Unit tests validation with mock AWS client interfaces and testing harnesses, verifying JSON marshaling, state validation, and router responses under failure conditions.

Telemetry Pipeline

Structured JSON logging emitted on health-check failures, standard error output capture, and historical pulse trendlines rendered in the frontend to visualize operational availability.

Design Trade-offs & Verification Logs

Humble Pivots

Serverless S3 Over Relational DB

Chose S3 JSON storage rather than DynamoDB or RDS. This minimized running costs and database operational overhead, since fleet snapshots and short histories only require basic key-value read/write access patterns.

Lambda Function URLs Instead of API Gateway

Avoided API Gateway for the backend API by utilizing Lambda Function URLs. This significantly reduced infrastructure complexity, since the project did not need advanced routing, request transformation, or edge authorizers at this stage.

Objective Clarity

Evaluated under single-writer assumptions. Up to 5 monitored endpoints with concurrent execution checks capped to 10-second request timeouts to prevent AWS Lambda execution drift and control costs.

Verifiable Outputs

Validation Suite (Unit Tests)

=== RUN   TestRouter
=== RUN   TestRouter/health_returns_healthy_response
=== RUN   TestRouter/check_accepts_post
=== RUN   TestRouter/latest_returns_stored_snapshot
=== RUN   TestRouter/history_returns_stored_entries
--- PASS: TestRouter (0.00s)
    --- PASS: TestRouter/health_returns_healthy_response (0.00s)
    --- PASS: TestRouter/check_accepts_post (0.00s)
    --- PASS: TestRouter/latest_returns_stored_snapshot (0.00s)
    --- PASS: TestRouter/history_returns_stored_entries (0.00s)
PASS
ok  	uptime-monitor/internal/api	0.004s

=== RUN   TestCheck
=== RUN   TestCheck/marks_200_response_up
=== RUN   TestCheck/marks_500_response_down
=== RUN   TestCheck/records_request_error
--- PASS: TestCheck (0.00s)
    --- PASS: TestCheck/marks_200_response_up (0.00s)
    --- PASS: TestCheck/marks_500_response_down (0.00s)
    --- PASS: TestCheck/records_request_error (0.00s)
PASS
ok  	uptime-monitor/internal/monitor	0.003s

=== RUN   TestStoreLatest
=== RUN   TestStoreLatest/returns_stored_latest_response
--- PASS: TestStoreLatest (0.00s)
    --- PASS: TestStoreLatest/returns_stored_latest_response (0.00s)
=== RUN   TestStoreHistory
=== RUN   TestStoreHistory/returns_stored_history_response
--- PASS: TestStoreHistory (0.00s)
    --- PASS: TestStoreHistory/returns_stored_history_response (0.00s)
PASS
ok  	uptime-monitor/internal/storage	0.004s