Breaking up a monolith into event-driven services

DabljaAR, our graduation project, dubs English videos into Arabic: speech-to-text, then translation, then text-to-speech, then merging the result back into the video. The first version was a FastAPI modular monolith with Celery workers on Redis.

The pipeline became an orchestrator plus speech-to-text, translation, text-to-speech, media and merge services, each consuming its own stage from RabbitMQ; an intermediate version used gRPC.

As team lead I owned the system design and all the infrastructure, and I led the design and the migration with the team. Teammates implemented parts of it, for example the Go orchestrator.

The code is in the public repository. On the infrastructure side I set up service-level indicators and objectives with Prometheus and Grafana, distributed tracing with OpenTelemetry and Jaeger, security-scanning CI and a GitOps workflow.