@rhodrin,

Two actions “owner/action1@v2” and “owner/action2@master”.
If you want ‘action1’ only is downloaded and build to run on ‘runner1’, and ‘action2’ only on ‘runner2’, you can try to set your matrix like as this:

jobs:
  job1:
    name: Test
    runs-on: ${{ matrix.runner }}
    strategy:
      matrix:
        include:
          - { runner: runner1, action_repos: 'owner/action1', action_ref: 'v2', s_name: 'step name to run action1' }
          - { runner: runner2, action_repos: 'owner/action2', action_ref: 'master', s_name: 'step name to run action2' }
    steps:
      - name: Checkout action code
        uses: actions/checkout@v2.3.2
        with:
          repository: ${{ matrix.action_repos }}
          ref: ${{ matrix.action_ref }}
          path: 'uses_action'
  - name: ${{ matrix.s_name }}
    uses: ./uses_action

In this way, the source code of the action will be downloaded via the checkout action. If the the action is docker action, the docker build will be executed in the step when running the action, it will not do the docker build before this step.

In your case, you also can set the matrix like this:

jobs:
  job1:
    name: Test
    runs-on: ${{ matrix.runner }}
    strategy:
      matrix:
        include:
          - { runner: runner1 }
          - { runner: runner2, action_repos: 'some_name/some-action', action_ref: 'master', s_name: 'Do something' }
    steps:
      - name: Checkout repo
        if: matrix.runner == 'runner1'
        uses: actions/checkout@v2.3.2
  - name: Checkout action code
    if: matrix.runner == 'runner2'
    uses: actions/checkout@v2.3.2
    with:
      repository: ${{ matrix.action_repos }}
      ref: ${{ matrix.action_ref }}
      path: 'uses_action'

  - name: ${{ matrix.s_name }}
    if: matrix.runner == 'runner2'
    uses: ./uses_action

@brightran

Thanks for the reply and suggestion. Modifying the matrix to contain information about which runner requires which actions is not really an ideal solution in this instance for a variety of reasons, but I’ll have a think re. the best way forward.

Having a more ‘intelligent’ download and build phase based on if statements present would of course be the ideal solution.

@brightran Ok, I see - that could potentially work nicely, will try it out. Thanks again for the help.