Dynamic mutexes

[Gitopolis]

Summary

Dynamically generate list of mutexes from an expression, something like:

spec:
  synchronization:
    mutexesFrom:
    - expression: "{{ workflow.inputs.modified | toJson }}"

Use Cases

A workflow processing modified files for every commit to some git repository. The input from the webhook might look something like this:

commits:
- modified:
  - file_a
  - file_b
- modified:
  - file_c
- modified:
  - file_d
- modified:
  - file_a

I want to run workflows/steps in parallel for processing files file_c and file_d, but processing file_a must not interfere with each other. So it would make sense to have mutexes equal to modified file names:

• workflow1

  synchronization:
    mutexes:
    - name:  <repo-name>/file_a
    - name:  <repo-name>/file_b

• workflow2

  synchronization:
    mutexes:
    - name:  <repo-name>/file_c

• workflow3

  synchronization:
    mutexes:
    - name:  <repo-name>/file_d

• workflow4

  synchronization:
    mutexes:
    - name:  <repo-name>/file_a

Currently there is no way to generate list of mutexes on runtime, so I use just <repo-name>, and that makes the processing unreasonably slow

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[Bellk17]

Second