ci: Add path-based triggers to CI workflows

[arielvalentin]

This should skip running tests for cases where it is not needed

Fixes: #1753

Skipping changes to instrumentation-with-services:

[xuan-cao-swi]

I think it will still trigger all instrumentation test to run even if I only modified the file inside e.g. http/.

Just an idea: the matrix can be modified

  detect-changes:
    runs-on: ubuntu-latest
    outputs:
      matrix: ${{ steps.set-matrix.outputs.matrix }}
    steps:
      ...

      - name: Get changed instrumentation files
        id: changed-files
        run: |
          if [[ "${{ github.event_name }}" == "schedule" ]] || [[ "${{ github.event_name }}" == "workflow_dispatch" ]]; then
            echo "run_all=true" >> $GITHUB_OUTPUT
          else
            echo "run_all=false" >> $GITHUB_OUTPUT
            echo "changed_gems=$(git diff --name-only ...)" >> $GITHUB_OUTPUT
          fi
      
      - name: Set matrix
        id: set-matrix
        run: |
          # get CHANGED_GEMS from last step
          echo "matrix={\"gem\":$CHANGED_GEMS,\"os\":[\"ubuntu-latest\"]}" >> $GITHUB_OUTPUT

  instrumentation:
    needs: detect-changes
    if: ${{ needs.detect-changes.outputs.matrix != '' && fromJson(needs.detect-changes.outputs.matrix).gem[0] != null }}
    strategy:
      fail-fast: false
      matrix: ${{ fromJson(needs.detect-changes.outputs.matrix) }}

    name: ${{ matrix.gem }} / ${{ matrix.os }}
    runs-on: ${{ matrix.os }}
    steps:
      - uses: actions/checkout@v5
      - name: "Test Ruby 3.4"
        ...

[arielvalentin]

Oh I see what you mean.

If an instrumentation changes, there are too many interdependencies at the moment between helpers, frameworks and HTTP etc.. so I do want them to run together.

For example, if I change instrumentation/active_support I also want to tests for anything that depends on that gem e.g. action_view.

It is a bit difficult to encode that as a set of dependencies to make sure they all run together.

Now that I think about it, changes to instrumentation/base and helpers should also trigger Instrumentation with services since those are critical dependencies for those libraries as well.

[xuan-cao-swi]

Same as last comment, if I only modified resources/, I probably only want resources/ to run test.

With paths-filter, we can use the output from detect-changes to decide on what jobs to run

jobs:
  detect-changes:
    runs-on: ubuntu-latest
    outputs:
      helpers: ${{ steps.filter.outputs.helpers }}
      propagators: ${{ steps.filter.outputs.propagators }}
      ...
    steps:
      - uses: actions/checkout@v5
      - uses: dorny/paths-filter@v3
        id: filter
        with:
          filters: |
            helpers:
              - 'helpers/**'
            propagators:
              - 'propagator/**'
            ...

  helpers:
    needs: detect-changes
    if: ${{ needs.detect-changes.outputs.helpers == 'true' || github.event_name == 'schedule' || github.event_name == 'workflow_dispatch' }}

  propagators:
    ...

[arielvalentin]

Reviewed in the SIG and I missed a few paths triggers so I am going to see if I could use anchors to avoid structural duplication

[arielvalentin]

@open-telemetry/ruby-contrib-approvers per our chat during the SIG, I have removed duplication in the actions workflows by using YAML anchors.

[kaylareopelle]

Thanks for working on this, @arielvalentin! This seems like a huge improvement. I have a few questions before I approve.