Transaction platform Technical lead 2025

Monolith to Microservices on AWS ECS

Decomposed a 24+ module transaction monorepo into independently deployable services while preserving external API contracts and workflow orchestration.

Key outcomes

Modules decomposed: 24+
Breaking API changes: 0
Fargate deployment target: ECS

Problem

A large transaction-processing monorepo with 24+ modules and multiple APIs sharing the same context path created deployment bottlenecks, tight coupling, and slow release cycles. Any change risked affecting unrelated modules, and the team could not deploy services independently.

Before → after

Deployment model
Before24+ modules in one monorepo, shared context path
AfterIndependently deployable services on ECS Fargate
API consumers
BeforeEvery release coordinated monolith-wide
AfterSame external routes via Traefik, 0 breaking changes

Architecture

Architecture · simplifiedContract-preserving decomposition on ECS Fargate

Clients

External API consumers

Unchanged URLs and context paths

same routes

Traefik

Reverse-proxy routing

Preserves external API access patterns

AWS ECS Fargate · independently deployable

svc

Transaction domain 1

svc

Transaction domain 2

svc

Transaction domain n

24+ modules split along transaction domains

Workflow engine

Process orchestration

Kept compatible across decomposed services

GitHub Actions · GitOps

Automated, repeatable rollouts

Each service ships on its own cadence

External API consumers keep calling the same routes. Traefik reverse-proxy routing sends each path to an independently deployable service on AWS ECS Fargate, split along transaction domains. Workflow orchestration stays compatible across the separated services, and GitHub Actions GitOps workflows roll each service out independently.

Approach

01Identified service boundaries aligned with transaction domains while keeping workflow orchestration compatible.
02Introduced Traefik reverse-proxy routing to preserve existing external API access patterns during and after migration.
03Deployed services on AWS ECS Fargate with GitHub Actions-based GitOps workflows for automated, repeatable rollouts.
04Migrated incrementally - one service at a time - validating each cutover against production traffic patterns.

Outcome

Services deploy independently with reduced coupling across the platform.
External API consumers experienced no breaking changes during migration.
Release cycles accelerated as teams could ship without coordinating monolith-wide deployments.
Workflow orchestration remained intact across the decomposed architecture.

Technologies

Java
Workflow orchestration
AWS ECS
Traefik
GitOps

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