[mariusae]

> I want an Airflow that runs and scales in the cloud

I'd encourage you to look at Reflow [1] which takes a different approach: it's entirely self-managing: you run Reflow like you would a normal programming language interpreter ("reflow run myjob.rf") and Reflow creates ephemeral nodes that scale elastically and that tear themselves down, only for the purpose of running the program.

> has extensive observability (monitoring, tracing)

Reflow includes a good amount of observability tools out of the box; we're also working on integrating tracing facilities (e.g., reporting progress to Amazon x-ray).

> has a full API, and maybe some clear way to test workflows.

Reflow's approach to testing is exactly like any other programming language: you write modules that can either be used in a "main" program, or else be used in tests.

[1] https://github.com/grailbio/reflow