`ansible_ssh_password` support

[moreati]

Based on original PR #1107 by @madsi1m, which I accidentally clobbered (see https://github.com/mitogen-hq/mitogen/pull/1107#issuecomment-2328528596).

Fixes #1106.

[moreati]

That was unexpected. The new tests failed across the board https://dev.azure.com/mitogen-hq/mitogen/_build/results?buildId=908, e.g.

TASK [ansible_ssh_password ] ***************************************************
Wednesday 04 September 2024  10:49:43 +0000 (0:00:00.105)       0:07:41.566 *** 
fatal: [target-centos6-1]: UNREACHABLE! => changed=false 
  msg: SSH password is incorrect
  unreachable: true

[moreati]

That was unexpected. The new tests failed across the board

This is probably because ansible_password, and ansible_ssh_pass have legacy support in Ansible. THey predate the modern plugin variables options mechanism that ansible_ssh_password is exposed through, and that Mitogen doesn't properly use (if at all). There are probably existing Mitogen issues and or PRs that touch on this.

See

• ansible.constants.COMMON_CONNECTION_VARS?
• ansible.constants.MAGIC_VARIABLE_MAPPING
• ansible.playbook.play_context.RESET_VARS?

[moreati]

Survey of attributes/expressions currently used

ansible_mitogen.transport_config.PlayContextSpec

• self._play_context.<thing>
• become_plugin.get_option('<thing>', playcontext=self._play_context)
• self._connection.get_task_var('ansible_<thing>')
• C.config.get_config_value("<thing>", plugin_type="connection", plugin_name="ssh", variables=self._task_vars.get("vars", {}))
• C.config.get_config_value("<thing>", plugin_type="connection", plugin_name="ssh", variables=self._task_vars.get("hostvars", {}).get(self._inventory_name, {}))

Notes to self

• self._task_vars intialiased at instantiation, vs self._connection.get_task_var() within individual methods
• self._task_vars.get('vars') vs self._task_vars.get('hostvars')

[moreati]

From https://docs.ansible.com/ansible/10/dev_guide/developing_plugins.html#plugin-configuration-documentation-standards

New plugins should define options: in the DOCUMENTATION string of their Python module.

Callback and connection plugins have declared configuration requirements this way since Ansible version 2.4; most plugin types now do the same.

To access the configuration settings in your plugin, use self.get_option(<option_name>). [...] Become, callback, connection and shell plugins are guaranteed to have the engine call set_options(). [...] Vars plugin settings are populated when first accessed (using the self.get_option() or self.get_options() method.

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From https://docs.ansible.com/ansible/10/dev_guide/developing_plugins.html#vars-plugins

Playbook constructs like ‘host_vars’ and ‘group_vars’ work using vars plugins.

Most of the work now happens in the get_vars method which is called from the VariableManager when needed.

[moreati]

/AzurePipelines run

[azure-pipelines[bot]]

Azure Pipelines successfully started running 1 pipeline(s).

[moreati]

After a lot of experimentation I think ansible.plugins.AnsiblePlugin.get_option() can be a basis for replacing the variety of techniques in ansible_mitogen.transport_config.PlayContextSpec() et al. Open questions

• [x] At the moment it requires ...get_option(..., hostvars=tasks_vars) how expensive is it to provide task_vars every time?
• [x] What is the difference between task vars, and host vars (HostVars) in the Ansible code base?
• [x] How should ansible_mitogen.transport_config.MitogenViaSpec() be updated/treated?
• [x] How should ansible_mitogen.plugins.* populate DOCUMENTATION options?
• [x] How should the expanded combinations of templating, variables overrides be tested?

[moreati]

At the moment it requires ...get_option(..., hostvars=tasks_vars) how expensive is it to provide task_vars every time?

PlayContextSpec.__init__() already calls Connection._get_task_vars(), so there is no additional cost.

[moreati]

How should ansible_mitogen.plugins.* populate DOCUMENTATION options?

This works for the ssh plugin atleast, but it's ugly as sin.

# This specifically has to be from ... import ..., to avoid some *waves hands* post import shuffling
# that ansible does to the sys.modules entry of ansible.plugins.ssh that results in AtrributeError
from ansible.plugins.connection.ssh import DOCUMENTATION as _ansible_ssh_DOCUMENTATION

DOCUMENTATION = """
    name: ...
    ...
    options:
""" + _ansible_ssh_DOCUMENTATION.partition('options:\n')[2]

It doesn't handle

• documentation fragments. For the mitiogen and specfically the connection_pipelining fragment this may not matter.
• documentation in a yaml file. This probably doesn't matter for now.

[moreati]

That was a hell of a journey. Some washup items

What is the difference between task vars, and host vars (HostVars) in the Ansible code base?

I think

1. Task vars are all the variables set when a particular task (or looped task) is running.
2. Host vars are one source amongst many that feed into task vars.
3. Some Ansible internal APIs call a parameter hostvars when they mean task vars.

How should ansible_mitogen.transport_config.MitogenViaSpec() be updated/treated?

Worth it's own issue, #1135.