Support multiple workspace types per scheduler

[d4l3k]

Description

Currently a scheduler is tied to a specific image type. Some schedulers such as LSF (and Slurm) support multiple different types of images. Ideally we could allow swapping in multiple different workspace backends to enable this in a more easy to use way.

Detailed Proposal

1. Add some new syntax to the --workspace entrypoint to allow specifying different types of workspaces --workspace=docker:. or perhaps with a --workspace-type docker.

2. Change the Workspace interaction with the schedulers to allow for setting more than one available workspace type per scheduler.

class FooScheduler(Scheduler):
    WORKSPACES: Iterable[Workspace] = (DockerWorkspace, DirWorkspace)

3. Update runner to be aware of the new workspace selectors

Alternatives

Additional context/links

• Will depend on Add per workspace runopts/config #589 since it removes workspace specific configs from runopts
• add LSF scheduler #588 - lsf scheduler PR

[kurman]

Will workspace still be synonymous with a 'patch' here?

[d4l3k]

Yeah -- would be. Just allows for different types of images/patching with the same scheduler