ops_test.model.deploy behavior not the same as juju 3.6-beta deploy behavior with respect to chosen base of application to deploy

[shayancanonical]

Description

We are using ops_test.model.deploy in our integration tests. While testing with juju 3.4.4 (along with python-libjuju ^3.2.2) we are able to run the following code:

await ops_test.model.deploy(
    "mysql-test-app",
    application_name="mysql-test-app1",
    num_units=1,
    channel="latest/edge",
)

However, while testing with juju 3.6-beta2 (along with python-libjuju 3.5.2.0), running the above code pulls in base ubuntu@20.04/stable sometimes and base ubuntu@22.04/stable other times. The charm mysql-test-app is available for both focal and jammy.

Example of the same code but different bases pulled:

• ubuntu@22.04/stable: https://github.com/canonical/mysql-operator/actions/runs/10267374503/job/28408646625?pr=502#step:28:412
• ubuntu@20.04/stable: https://github.com/canonical/mysql-operator/actions/runs/10267374503/job/28408648062?pr=502#step:28:235

Because (likely) juju 3.6 no longer supports certain bases (like ubuntu@20.04/stable), the default base python-libjuju uses in ops_test.model.deploy() fails with an error trace (shown in the reproduce section)

Urgency

Annoying bug in our test suite

Python-libjuju version

3.5.2.0

Juju version

3.6-beta2-ubuntu-amd64

Reproduce / Test

Using:

await ops_test.model.deploy(
    "mysql-test-app",
    application_name="mysql-test-app1",
    num_units=1,
    channel="latest/edge",
)

We get the following trace:

=============================================== FAILURES ================================================
_________________________________________ test_build_and_deploy _________________________________________
Traceback (most recent call last):
  File "/home/shayanp/code/mysql-operator/.tox/integration/lib/python3.10/site-packages/_pytest/runner.py", line 341, in from_call
    result: Optional[TResult] = func()
  File "/home/shayanp/code/mysql-operator/.tox/integration/lib/python3.10/site-packages/_pytest/runner.py", line 262, in <lambda>
    lambda: ihook(item=item, **kwds), when=when, reraise=reraise
  File "/home/shayanp/code/mysql-operator/.tox/integration/lib/python3.10/site-packages/pluggy/_hooks.py", line 433, in __call__
    return self._hookexec(self.name, self._hookimpls, kwargs, firstresult)
  File "/home/shayanp/code/mysql-operator/.tox/integration/lib/python3.10/site-packages/pluggy/_manager.py", line 112, in _hookexec
    return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
  File "/home/shayanp/code/mysql-operator/.tox/integration/lib/python3.10/site-packages/pluggy/_callers.py", line 155, in _multicall
    return outcome.get_result()
  File "/home/shayanp/code/mysql-operator/.tox/integration/lib/python3.10/site-packages/pluggy/_result.py", line 108, in get_result
    raise exc.with_traceback(exc.__traceback__)
  File "/home/shayanp/code/mysql-operator/.tox/integration/lib/python3.10/site-packages/pluggy/_callers.py", line 80, in _multicall
    res = hook_impl.function(*args)
  File "/home/shayanp/code/mysql-operator/.tox/integration/lib/python3.10/site-packages/_pytest/runner.py", line 177, in pytest_runtest_call
    raise e
  File "/home/shayanp/code/mysql-operator/.tox/integration/lib/python3.10/site-packages/_pytest/runner.py", line 169, in pytest_runtest_call
    item.runtest()
  File "/home/shayanp/code/mysql-operator/.tox/integration/lib/python3.10/site-packages/_pytest/python.py", line 1792, in runtest
    self.ihook.pytest_pyfunc_call(pyfuncitem=self)
  File "/home/shayanp/code/mysql-operator/.tox/integration/lib/python3.10/site-packages/pluggy/_hooks.py", line 433, in __call__
    return self._hookexec(self.name, self._hookimpls, kwargs, firstresult)
  File "/home/shayanp/code/mysql-operator/.tox/integration/lib/python3.10/site-packages/pluggy/_manager.py", line 112, in _hookexec
    return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
  File "/home/shayanp/code/mysql-operator/.tox/integration/lib/python3.10/site-packages/pluggy/_callers.py", line 155, in _multicall
    return outcome.get_result()
  File "/home/shayanp/code/mysql-operator/.tox/integration/lib/python3.10/site-packages/pluggy/_result.py", line 108, in get_result
    raise exc.with_traceback(exc.__traceback__)
  File "/home/shayanp/code/mysql-operator/.tox/integration/lib/python3.10/site-packages/pluggy/_callers.py", line 80, in _multicall
    res = hook_impl.function(*args)
  File "/home/shayanp/code/mysql-operator/.tox/integration/lib/python3.10/site-packages/_pytest/python.py", line 194, in pytest_pyfunc_call
    result = testfunction(**testargs)
  File "/home/shayanp/code/mysql-operator/.tox/integration/lib/python3.10/site-packages/pytest_asyncio/plugin.py", line 532, in inner
    _loop.run_until_complete(task)
  File "/usr/lib/python3.10/asyncio/base_events.py", line 649, in run_until_complete
    return future.result()
  File "/home/shayanp/code/mysql-operator/tests/integration/test_deploy_base.py", line 16, in test_build_and_deploy
    await ops_test.model.deploy(
  File "/home/shayanp/code/mysql-operator/.tox/integration/lib/python3.10/site-packages/juju/model.py", line 1841, in deploy
    return await self._deploy(
  File "/home/shayanp/code/mysql-operator/.tox/integration/lib/python3.10/site-packages/juju/model.py", line 2163, in _deploy
    raise JujuError('\n'.join(errors))
juju.errors.JujuError: base "ubuntu@20.04/stable" is not supported, supported bases are: ubuntu@22.04
------------------------------------------ Captured log setup -----------------------------------------

Using juju 3.6-beta2 directly:

shayanp@brisbane:~/code/mysql-operator$ juju3.6.beta deploy -n 1 mysql-test-app 
Deployed "mysql-test-app" from charm-hub charm "mysql-test-app", revision 46 in channel latest/stable on ubuntu@22.04/stable
shayanp@brisbane:~/code/mysql-operator$ juju3.6.beta deploy -n 1 mysql-test-app mysql-test-app2
Deployed "mysql-test-app2" from charm-hub charm "mysql-test-app", revision 46 in channel latest/stable on ubuntu@22.04/stable
shayanp@brisbane:~/code/mysql-operator$ juju3.6.beta deploy -n 1 mysql-test-app mysql-test-app3
Deployed "mysql-test-app3" from charm-hub charm "mysql-test-app", revision 46 in channel latest/stable on ubuntu@22.04/stable

[hmlanigan]

@shayancanonical are you able to work around this issue by specifying the base to use?

[shayancanonical]

@hmlanigan yes, i had to explicitly specify the base as a workaround to continue with testing our charms with juju 3.6-beta

[taurus-forever]

Hi, we have started testing juju 3.6 nightly and it affects our CI.
JFMI: is the fix planned here anytime soon (as Juju 3.6 LTS is approaching).

Thank you!