Use concurrency option of GH actions to cancel previous workflow runs

[lars-reimann]

Is your feature request related to a problem? Please describe.
This is a follow-up to #622, i.e. about cancelling previous workflow runs when a new push to a branch occurs.

Describe the solution you'd like
GitHub actions directly offers a means to prevent concurrent workflow runs and concurrent job runs and to cancel any previous runs.

Advantages:

• It's not another job, so
  • cancellation happens faster,
  • it does not show up as a check in PRs,
  • you don't get billed for it.

Disadvantages:

• skip-duplicate-actions offers more options.
• One needs to be careful that only the mega-linter workflow is cancelled by assigning a unique concurrency group.

Example:

name: Mega-Linter

on:
  pull_request:
    branches: [main]

# Workflow can only run once per branch and any previous pending or in-progress runs are cancelled.
concurrency:
  group: ${{ github.ref }}-${{ github.workflow }}
  cancel-in-progress: true

env:
  APPLY_FIXES: all
  APPLY_FIXES_EVENT: pull_request
  APPLY_FIXES_MODE: commit
  FILTER_REGEX_EXCLUDE: (\.github/workflows/)

jobs:
  lint:
    # As usual...

Describe alternatives you've considered
Keep everything as is, which is also perfectly acceptable (so feel free to close this).

Additional context
Links (same as above):

• Workflow concurrency
• Job concurrency

[nvuillam]

Oh, that's new to GHA Workflow ? Great , it would indeed be faster than the action we use today

Are you in the mood for a PR ? Template to update is here -> https://github.com/megalinter/megalinter/blob/main/mega-linter-runner/generators/mega-linter/templates/mega-linter.yml

If not, we'll definitely do that someday !

[lars-reimann]

I can have a look at it this weekend (at the latest).

[nvuillam]

That would be great , thanks :)

If you are a crazy coder you can also update the --upgrade option of mega-linter-runner, to do some regex search/replace to update existing workflows in repo where ML is already installed ^^ ( https://github.com/megalinter/megalinter/blob/main/mega-linter-runner/lib/upgrade.js )