TL;DR:

I switched one of our Github Workflows from using a Composite Action to using a Workflow with workflow_call to get a better UI in Github Actions, and a breakdown of steps in Datadog. There was 0 downsides.

Background

Our deploy Github workflow has a Composite Action to share a series of shared steps. The steps include things like: run a smoke build, install some dependencies, build a docker image, push it to a registry, etc. This worked, but it had a major flaw: a Composite Action is used as a "step" in an existing workflow:

jobs:
  my_job:
    name: "Job 1"
    runs-on: ubuntu-latest
    steps:
      - name: Step 1
        uses: ./.github/composite-actions/some-series-of-steps

This provides a nice abstraction, but all of some-action is collapsed into "Step 1" in the workflow. Apparently this is a long standing issue. This means we don't get log collapsing, bubbled up timing, etc for individual steps in this Composite Action.

Datadog

I was ok with this while it was just a UI issue. But we use the DataDog integration to collect CI information from Github Actions. This has been invaluable to analyze CI and optimize the slow bits. My typical workflow is to look at a Pipeline Executions (which are runs of a Github Workflow), break it down by the duration of each Job (which is a Github Job in a Workflow) and then dig into individual Steps. Because "some-action" is inlined into a single Step, DataDog just gets a single entry for the entire Composite Action. So you might know the Composite Action is slow, but have no idea which part.

The Fix

I replaced this Composite Action with another Workflow and enabled it to be invoked with a workflow_call event:

on:
  workflow_call:

and then

jobs:
  my_job:
    name: "Job 1"
    secrets: inherit
    uses: ./.github/workflows/some-series-of-steps.yml

The main difference is that the uses key appears at the job level instead of as a step, and you have to explicitly share secrets with it. After this change, each step in some-series-of-steps were individual steps in the Github Actions UI and also reported to DataDog separately.