Can pants manage external processes to coordinate setup and teardown steps for tests? I would like to be able to start/stop a local postgres instance when I run pants test ../..integration . Is that something I should just have tox/nox/ci coordinate?

There's an open issue for this: https://github.com/pantsbuild/pants/issues/17860

We do this for Python today with pytest fixtues along the lines of

@pytest.fixture(scope="session")
def docker_compose_file(pytestconfig):
    return os.path.join(
        str(pytestconfig.rootdir),
        "foo/bar/bax/docker-compose.yml",
    )