Kestra 2.0: a new engine, workers anywhere, and still Apache 2.0

In February 2022 I published my first post here, called Kestra, infinitely scalable open source orchestration and scheduling platform. I described an orchestrator using Kafka as both queue and database, Elasticsearch as the repository behind the UI, and I was proud of the 350,000 executions a month it was running at Leroy Merlin. Two things about that post did not survive contact with reality. The word "infinitely", which I have since retired. And the architecture, which people told me was far too heavy to even try. This is the follow-up, four years and one engine rewrite later. What the feedback changed first The most common reply to that 2022 post, in one form or another: requiring a Kafka cluster and an Elasticsearch cluster to schedule a job is absurd. That was fair. Four months later we shipped a JDBC backend, and a single Postgres or MySQL was enough to run everything, queue and state included. That set the pattern for the whole project. Someone tells us the deploym