Celebi / Concepts

Runner

The repository holds code and impressions — so why bother with an external runner? Because impressions should run flexibly: part of the work on your PC, part on HTCondor, and so on. And a running workflow should never block your development.

Three types of runner

• REANA runner — the most robust one; runs in containerized environments.
• Local runner — runs things on the machine that Yuki runs on.
• ssh runner — jobs are submitted to an ssh machine.

The latter two offer less reproducibility than containerized REANA execution.

How a runner works

1. Resolve the dependencies.
2. Copy the predecessors (code, plus the stageout folders of preceding nodes).
3. Run the command in the requested environment.
4. Retrieve the outputs (via Yuki).

Multiple tasks can be submitted with one action — e.g. running submit in a folder executes it in all child nodes.