Vol. XXXII · Issue 5 · Tampa, FL · May 2026
Fabio Santos.
Open · Tampa Contact
Lead Essay · Apr 2026

Why your agentic AI bill is 80% Lambda cold-starts (and the fix)

A walkthrough of FinOps for agentic platforms — where the money actually leaks, why provisioned concurrency isn't always right, and a battle-tested pattern for keeping AI compute under 30% of revenue.

11 min read ·
AI FinOps Serverless
Read the essay →
More writings.
5 essays · RSS
Mar 2026 14 min
RAG on OpenSearch vs. pgvector: what actually matters at scale

Side-by-side benchmark and operational notes from running both in production. Recall, ingest throughput, hybrid search, and the operational tax nobody talks about…

RAG OpenSearch Vector DB
Feb 2026 18 min
Multi-region from day one: an opinionated AWS playbook

What I'd do differently if I were starting Ripio's 6-country topology again. DynamoDB Global Tables, Aurora Global, Route 53 health checks, and where the latency math actually bites…

AWS Multi-Region SRE
Jan 2026 22 min
The 3,000 TPS architecture for <$10K/month — full breakdown

API Gateway → Lambda → DynamoDB single-table + Step Functions + EventBridge. Why provisioned concurrency mattered, where Step Functions hurt, and the single-table schema that…

Fintech Serverless DynamoDB
Dec 2025 7 min
Notes on hiring SREs in 2026

What I look for after 30+ years and three founding teams. Hint: it's not the cert list.

SRE Hiring ↗ external
Notes · microblog

Thinking out loud.

May 8

Today's reminder: spot price is not a strategy. Spot diversification is.

May 3

If your post-mortem template doesn't have a 'systemic' section, it's a blame template.

Apr 27

Bedrock + Claude for tool-use, OpenAI for streaming-heavy chat, Anthropic API direct for evals. Right tool for the job.

Apr 19

Karpenter + spot is the single biggest lever for EKS FinOps. Nothing else is close.

Apr 12

32 years in IT and I'm still rebuilding my dotfiles every Sunday morning. Some things never change.

On X · @fabioshenrique

From the feed.

X · @fabioshenrique · live follow on X
GitHub · fabios7

Lately I've been shipping.

last 12 weeks 1,284 commits / 12mo
lp-hive-agent/
feat(rag): hybrid reranker w/ cohere fallback
2h ago
lp-hive-agent/
chore: bump bedrock client to v3.842
5h ago
ragkit-cdk/
fix(opensearch): TLS-cert chain for cross-account ingest
yesterday
terraform-aws-eks-karpenter/
feat: spot diversification across 3 AZs by default
2d ago
personal-site/
design: tri-column resume + magic-link
3d ago
↗ See all on GitHub
Talks
On stage.
2025 · panel
Building agentic AI platforms on AWS
AWS re:Invent Community
2024 · talk
Crypto-as-a-Service: building Itaú's serverless platform
AWS Summit São Paulo
2023 · keynote
Multi-region crypto custody — the 6-country playbook
LATAM Fintech Summit
2022 · talk
PCI DSS on AWS without slowing your team
DevOps Days Miami
Teaching
Courses I can minister.
AWS Architecture for Fintechs
16h · 4 sessions
Live online or in-house workshop · Senior engineers / staff+
  • Multi-region topology, RPO/RTO trade-offs
  • Serverless-first vs containers — when each wins
  • DynamoDB single-table design at TPS scale
Open enrollment · Q3 2026 Request →
Production RAG: from prototype to scale
12h · 3 sessions
Live online · corporate cohort · AI engineers / platform teams
  • Ingest pipelines on AWS (S3 + Lambda + OpenSearch)
  • Chunking & retrieval strategies that survive real data
  • Hybrid search, reranking, evals
Open enrollment · Q4 2026 Request →
SRE for Crypto & Payments
8h · 2 sessions
Half-day intensive · Eng leads / SREs
  • SLOs and error budgets for regulated workloads
  • Multi-region active-active patterns
  • Incident response in compliance-heavy environments
By request Request →
Reading
On the nightstand.
Designing Data-Intensive Applications
Martin Kleppmann
Re-reading
Site Reliability Engineering
Google SRE Team
Reference
The Manager's Path
Camille Fournier
Recommending
Building LLM apps for Production
Chip Huyen
Reading
Tools daily
Editor:Neovim · VS Code · Cursor
Terminal:Ghostty · zsh + starship · tmux
Notes:Obsidian · Apple Notes
Hardware:MacBook Pro M3 Max · Studio Display · Logitech MX Master 3
AI daily:Claude (chat + code) · Cursor · Aider
Open source.
3 projects · MIT
Maintainer terraform-aws-eks-karpenter

Opinionated EKS + Karpenter module battle-tested at 6-country scale.

Author ragkit-cdk

CDK construct library for production RAG on AWS (OpenSearch + Bedrock + Lambda).

Author post-mortem-template

Blameless post-mortem template I've used across 4 companies.

The Newsletter
The Patterns.

A short letter, every other week. One battle-tested pattern from production cloud / AI work. No filler.

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