Add support for multiple ssh backends

[tpapaioa]

• Add support for hussh and ansible-pylibssh libraries
• Add ssh_backend: ssh2-python312 default setting to broker_settings.yaml.example. To use hussh or ansible-pylibssh, install the package and then override the setting in the local broker_settings.yaml file, or with the BROKER_SSH_BACKEND environment variable:

$ pip install hussh
$ BROKER_SSH_BACKEND="hussh" broker inventory
[INFO 240408 14:39:58] SSH_BACKEND='hussh'
[...]

$ pip install ansible-pylibssh
$ BROKER_SSH_BACKEND="ansible-pylibssh" broker inventory
[INFO 240408 16:15:32] SSH_BACKEND='ansible-pylibssh'
[...]

Verified functional tests:

$ BROKER_SSH_BACKEND="hussh" pytest -k test_satlab
=== test session starts ===
[...]
collected 68 items / 58 deselected / 10 selected

tests/functional/test_satlab.py::test_checkout_scenarios[args_file0] PASSED [ 10%]
tests/functional/test_satlab.py::test_checkout_scenarios[args_file1] PASSED [ 20%]
tests/functional/test_satlab.py::test_checkout_scenarios[args_file2] PASSED [ 30%]
tests/functional/test_satlab.py::test_checkout_scenarios[args_file3] PASSED [ 40%]
tests/functional/test_satlab.py::test_execute_scenarios[args_file0] PASSED  [ 50%]
tests/functional/test_satlab.py::test_inventory_sync PASSED                 [ 60%]
tests/functional/test_satlab.py::test_workflows_list PASSED                 [ 70%]
tests/functional/test_satlab.py::test_workflow_query PASSED                 [ 80%]
tests/functional/test_satlab.py::test_tower_host PASSED                     [ 90%]
tests/functional/test_satlab.py::test_tower_host_mp PASSED                  [100%]
=== 10 passed, 58 deselected, 49 warnings in 4216.30s (1:10:16) ===

****

$ BROKER_SSH_BACKEND="ansible-pylibssh" pytest -k test_satlab
=== test session starts ===
[...]
collected 68 items / 58 deselected / 10 selected

tests/functional/test_satlab.py::test_checkout_scenarios[args_file0] PASSED   [ 10%]
tests/functional/test_satlab.py::test_checkout_scenarios[args_file1] PASSED   [ 20%]
tests/functional/test_satlab.py::test_checkout_scenarios[args_file2] PASSED   [ 30%]
tests/functional/test_satlab.py::test_checkout_scenarios[args_file3] PASSED   [ 40%]
tests/functional/test_satlab.py::test_execute_scenarios[args_file0] PASSED    [ 50%]
tests/functional/test_satlab.py::test_inventory_sync PASSED                   [ 60%]
tests/functional/test_satlab.py::test_workflows_list PASSED                   [ 70%]
tests/functional/test_satlab.py::test_workflow_query PASSED                   [ 80%]
tests/functional/test_satlab.py::test_tower_host PASSED                       [ 90%]
tests/functional/test_satlab.py::test_tower_host_mp PASSED                    [100%]
[...]
=== 10 passed, 58 deselected, 43 warnings in 3985.79s (1:06:25) ===

[tpapaioa]

Functional tests on ssh2-python312:

$ BROKER_SSH_BACKEND="ssh2-python312" pytest -k test_satlab
[...]
collected 68 items / 58 deselected / 10 selected

tests/functional/test_satlab.py::test_checkout_scenarios[args_file0] PASSED  [ 10%]
tests/functional/test_satlab.py::test_checkout_scenarios[args_file1] PASSED  [ 20%]
tests/functional/test_satlab.py::test_checkout_scenarios[args_file2] PASSED  [ 30%]
tests/functional/test_satlab.py::test_checkout_scenarios[args_file3] PASSED  [ 40%]
tests/functional/test_satlab.py::test_execute_scenarios[args_file0] PASSED   [ 50%]
tests/functional/test_satlab.py::test_inventory_sync PASSED                  [ 60%]
tests/functional/test_satlab.py::test_workflows_list PASSED                  [ 70%]
tests/functional/test_satlab.py::test_workflow_query PASSED                  [ 80%]
tests/functional/test_satlab.py::test_tower_host PASSED                      [ 90%]
tests/functional/test_satlab.py::test_tower_host_mp PASSED                   [100%]
[...]
=== 10 passed, 58 deselected, 45 warnings in 4045.79s (1:07:25) ===

[tpapaioa]

Updated functional test ids for parametrized scenario tests, to show the scenario file name instead of the default, less informative, ids created by pytest.

Before:

$ pytest --co -k 'test_checkout_scenarios or test_execute_scenarios'
[...]
collected 68 items / 58 deselected / 10 selected

<Dir broker>
  <Dir tests>
    <Dir functional>
      <Module test_containers.py>
        <Function test_checkout_scenarios[args_file0]>
        <Function test_checkout_scenarios[args_file1]>
        <Function test_execute_scenarios[args_file0]>
      <Module test_rh_beaker.py>
        <Function test_checkout_scenarios[args_file0]>
        <Function test_checkout_scenarios[args_file1]>
      <Module test_satlab.py>
        <Function test_checkout_scenarios[args_file0]>
        <Function test_checkout_scenarios[args_file1]>
        <Function test_checkout_scenarios[args_file2]>
        <Function test_checkout_scenarios[args_file3]>
        <Function test_execute_scenarios[args_file0]>

After:

$ pytest --co -k 'test_checkout_scenarios or test_execute_scenarios'
[...]
collected 68 items / 58 deselected / 10 selected

<Dir broker>
  <Dir tests>
    <Dir functional>
      <Module test_containers.py>
        <Function test_checkout_scenarios[checkout_ch-d_ubi8]>
        <Function test_checkout_scenarios[checkout_ch-d_ubi8_2]>
        <Function test_execute_scenarios[execute_ch-d_ubi8]>
      <Module test_rh_beaker.py>
        <Function test_checkout_scenarios[checkout_test_job-2]>
        <Function test_checkout_scenarios[checkout_test_job]>
      <Module test_satlab.py>
        <Function test_checkout_scenarios[checkout_latest_sat]>
        <Function test_checkout_scenarios[checkout_latest_rhel]>
        <Function test_checkout_scenarios[checkout_rhel91]>
        <Function test_checkout_scenarios[checkout_sat_613]>
        <Function test_execute_scenarios[execute_templates_list]>

[JacobCallahan]

Great work overall! Just some relatively minor notes.

[JacobCallahan]

This is more of an organization suggestion, but I think these shouldn't live at this level. I think it makes sense to move these under the binds directory and strip ssh_session from the module name.

Suggested change

	if SSH_BACKEND == "ansible-pylibssh":
	from broker.ssh_session_pylibssh import InteractiveShell, Session
	elif SSH_BACKEND == "hussh":
	from broker.ssh_session_hussh import Session
	elif SSH_BACKEND in ("ssh2-python", "ssh2-python312"):
	from broker.ssh_session_ssh2 import InteractiveShell, Session # noqa: F401
	if SSH_BACKEND == "ansible-pylibssh":
	from broker.binds.pylibssh import InteractiveShell, Session
	elif SSH_BACKEND == "hussh":
	from broker.binds.hussh import Session
	elif SSH_BACKEND in ("ssh2-python", "ssh2-python312"):
	from broker.binds.ssh2 import InteractiveShell, Session # noqa: F401

[tpapaioa]

Moved modules to binds directory.

[JacobCallahan]

Why can't the ssh_session module's contents live in this module?

[tpapaioa]

I had originally thought of using BaseSession as a base class for the individual backend classes. I've updated the import logic to create the default session class if a backend can't be imported.

[JacobCallahan]

ACK, thanks for taking this on!