Unit tests randomly fail to connect to ephemeral Prefect API server

[dgarros]

Bug summary

After upgrading to prefect 3.1.5 from 3.0.3, we have noticed that the ephemeral server is failing to start fairly often in our CI (1 out of 3 or 5 times on average)

When the issue happen, all tests fail with the following error message.

RuntimeError: Timed out while attempting to connect to ephemeral Prefect API server.

Here is how the fixture is defined

@pytest.fixture(scope="session")
def prefect_test_fixture():
    with prefect_test_harness():
        yield

The issue happens often in CI but it's been hard to reproduce it locally, not sure if this is related but in our CI we are using pytest-xdist to run

here is an example of a failed run in Github Action
https://github.com/opsmill/infrahub/actions/runs/12347503261/job/34454717567

The same job test was working reliably in 3.0.3

Version info

Version:             3.1.5
Python version:      3.12.7

List of pytest plugins we are using

pytest                                   7.4.4           pytest: simple pow...
pytest-asyncio                           0.21.2          Pytest support for...
pytest-benchmark                         4.0.0           A ``pytest`` fixtu...
pytest-clarity                           1.0.1           A plugin providing...
pytest-codspeed                          2.2.1           Pytest plugin to c...
pytest-cov                               4.1.0           Pytest plugin for ...
pytest-env                               1.1.3           pytest plugin that...
pytest-httpx                             0.30.0          Send responses to ...
pytest-timeout                           2.3.1           pytest plugin to a...
pytest-xdist                             3.4.0           pytest xdist plugi...

[dgarros]

For now we've reverted to 3.0.11 where the issue is not present