Refactor volumes for Flask & Celery

[uniqueg]

Problem

Both the Flask app and Celery containers write to the same shared data volume. This unnecessary dependency should be avoided if possible, not least because it complicates deployment.

At the moment, the Flask app sets up a directory for each run, downloads a repo containing the workflow. Celery then reads the workflow and executes it via cwl-tes and and writes temporary files out (a side effect of cwl-tes / cwltool; see #157).

Describe the solution you'd like

Enumerate and describe the read/write operations of each service and assess whether they are (a) require a shared volume and (b) necessary at all. Depending on the assessment, if possible, refactor such that the Flask app does not require any data volume at all (preferred) or that it uses a different data volume than Celery.

Describe alternatives you've considered

N/A

Additional context

• Automatically create data subdirectories upon first start of app #122
• Service downloads all output files #157