close

PTEN

Will Peixoto with arms crossed, black t-shirt with the orange lambda

Will Peixoto

São Paulo, Brazil

Serverless, AWS architecture and AI agents: what I'd pick, why, and what it costs.

Staff Engineer at Serverless Guru. My topics usually come from a technical problem I had to solve or something I had to explain.

BUILD. SCALE. REPEAT.

focus
Serverless, architecture and AI agents on AWS
languages
Portuguese and English, on the blog and on stage
meetups
One of the leaders of AWS User Group São Paulo, 120+ meetups
events
Co-organizes ServerlessDays São Paulo
stage
Speaker and mentor at the Serverless + Agentic AI na AWS workshop (Sem Servidor, 2026)
Read the blog Invite me to speak

event-drivenPT · EN

Featured

New EventBridge Custom Event Bus vs SQS FIFO: when to switch

  1. Context

    Cross-team integration on EventBridge Classic, an SQS FIFO queue behind every consumer, an archive for replay and a resource policy that grows with every new account.

  2. Rule of thumb

    For a cross-team backbone, in a supported Region, with fast idempotent consumers and per-entity ordering within one publisher: new bus with per-account subscribers, no SQS FIFO in the middle.

  3. Trade-off
    What you gain

    Cross-account sharing through AWS RAM (Resource Access Manager), native retention and replay, and FIFO by EventGroupId, with fewer parts between teams.

    What you pay

    A 30 s ceiling on REQUEST_RESPONSE, head-of-line blocking during retries, ordering only within the publishing account, and no sa-east-1 yet.

Read the full post

Decision log

Every post ends in an architecture decision: the context, what I'd pick, what you gain and what you pay.

  1. serverless

    Serverless Isn't Failure-Proof: 7 Resilience Patterns with Code

    Serverless resilience patterns on AWS with TypeScript code: retry with jitter, idempotency, timeouts, Circuit Breaker, DLQ and graceful degradation.

  2. DynamoDB

    DynamoDB filtered export: export one tenant without paying for the whole table

    DynamoDB filtered export to S3 in a multi-tenant SaaS: only a key condition on the partition key cuts the cost. Math, TypeScript code and limits.

  3. architecturePT · EN

    Invisible Coupling: When Your Microservices Become a Distributed Monolith

    Rule of thumb: Synchronous only where an answer is needed right now. Everything else becomes an async event, with a durable layer in between.

    Context and trade-off

    Microservices with their own deploys and green dashboards go down together when one service at the end of a synchronous chain chokes.

    What you gain

    One slow service becomes a growing queue, not a checkout timeout.

    What you pay

    Designing boundaries and the hot path, and running the resilience patterns (Circuit Breaker, Bulkhead, Outbox), each with its own cost.

  4. lambdaPT · EN

    Lambda Web Functions: when to switch from Event Functions, and what to do with no South America region

    Rule of thumb: Web Functions for I/O-bound APIs and SSR, with data in us-east-1 and CloudFront + OAC in front. A database pinned to sa-east-1 stays on Event Functions.

    Context and trade-off

    Web Functions runs your Node.js HTTP server directly on Lambda, billing for active CPU, but launched with no South America region.

    What you gain

    Up to 128 requests per environment, no adapter, paying for active CPU instead of time spent waiting on the database.

    What you pay

    Requests cost 50% more, fixed 2 GB, Node.js 24 on Arm64 only, and zero request state in global variables.

    Would change if: sa-east-1 joins the region list.

See all posts

Community

Community is half the fun of this career. If you're starting out or want a stage for your first talk, come to a meetup and say hi.

AWS User Group São Paulo

one of the leaders

AWS meetups in São Paulo, past 120 of them. If you want a stage for your first talk, this is the place.

See upcoming meetups

ServerlessDays São Paulo

co-organizer

The serverless community event in São Paulo.

About the event

Talks

Talk, workshop, mentoring or panel, in Portuguese or English. Invitations reach me fastest by LinkedIn DM.

Sem Servidor, Florianópolis, Brazil, 17 Oct 2026

Serverless + Agentic AI na AWS

in-person workshop, talk and hands-on mentoring

Topics I speak on

  • Lambda durable functionslong-running workflows as plain sequential code, and when not to use them
  • Event-driven in the age of AI agentslevel 400what breaks in retries, schemas and loops when the consumer reasons
  • Serverless and event-driven on AWSpatterns, resilience and cost trade-offs in production
  • AI agents with serverless on AWSlevel 100from an LLM on Amazon Bedrock to an agent with Strands running on Lambda
  • AI agents and MCP on AWSidentity, governance and least privilege for agents
  • Lambda MicroVMsisolation for untrusted code
Invite me on LinkedIn See talks

Where to find me

Everything I publish starts here on the blog. Elsewhere you'll find the cross-posts, the conversations and new post alerts.

New posts, straight to your inbox

One serverless, architecture or AI agents topic on AWS per issue: what I'd pick, why, and what it costs. No spam.

Opens the subscription page in a new tab.