This implements the first edition of Connection Delegation, where
delegating connection establishment is initially single-threaded.
ansible_mitogen/strategy.py:
ansible_mitogen/plugins/connection/*:
Begin splitting connection.Connection into subclasses, exposing them
directly as "mitogen_ssh", "mitogen_local", etc. connection types.
This is far from removing strategy.py, but it's a tiny start.
ansible_mitogen/connection.py:
* config_from_play_context() and config_from_host_vars() build up a
huge dictionary containing either more or less PlayContext contents,
or our best attempt at reconstructing a host's connection config
from its hostvars, where that config is not the current
WorkerProcess target.
They both produce the same format with the same keys, allowing
remaining code to have a single input format.
These dicts contain fields named after how Ansible refers to them,
e.g. "sudo_exe".
* _config_from_via() parses a basic connection specification like
"username@inventory_name" into one of the aforementioned dicts.
* _stack_from_config() produces a list of dicts describing the order
in which (Mitogen) connections should be established, such that each
element is proxied via= the previous element. The dicts produced by
this function use Mitogen keyword arguments, the former di.
These dicts contain fields named after how Mitogen refers to them,
e.g. "sudo_path".
* Pass the stack to ContextService, which is responsible for actual
setup of the full chain.
ansible_mitogen/services.py:
Teach get() to walk the supplied stack, establishing each connection
in turn, creating refounts for it before continuing.
TODO: refcounting is broken in a variety of cases.
And by "compatible" I mean "terrible". This does not implement async job
timeouts, but I'm not going to bother, upstream async implementation is
so buggy and inconsistent it resists even having its behaviour captured
in tests.
Closes#105.
References #155.
mitogen/service.py:
Refactor services to support individually exposed methods with
different security policies for each method.
- @mitogen.service.expose() to expose a method and set its policy
- @mitogen.service.arg_spec() to validate input.
- Require basic service message format to be a tuple of
`(method, kwargs)`, where kwargs is always a dict.
- Update DeduplicatingService to match the new scheme.
ansible_mitogen/connection.py:
- Rename 'method' to 'method_name' to disambiguate it from the
service.call()'s method= argument.
ansible_mitogen/planner.py:
- Generate an ID for every job, sync or not, and fetch job results
from JobResultService rather than via the initiating function
call's return value.
- Planner subclasses now get to select whether their Runner should
run in a forked process. The base implementation requests this if
the 'mitogen_isolation_mode=fork' task variable is present.
ansible_mitogen/runner.py:
Teach runners to deliver their result via JobResultService executing
in their indirect parent mux process.
ansible_mitogen/plugins/actions/mitogen_async_status.py:
Split the implementation up into methods, and more compatibly
emulate Ansible's existing output.
ansible_mitogen/process.py:
Mux processes now host JobResultService.
ansible_mitogen/services.py:
Update existing services to the new mitogen.service scheme, and
implement JobResultService:
* listen() method for synchronous jobs. planner.invoke() registers a
Sender with the service prior to invoking the job, then sleeps
waiting for the service to write the job result to the
corresponding Receiver.
* Non-blocking get() method for implementing mitogen_async_status
action.
* Child-accessible push() method for delivering task results.
ansible_mitogen/target.py:
New helpers for spawning a virginal subprocess on startup, from
which asynchronous and mitogen_task_isolation=fork jobs are forked.
Necessary to avoid a task inheriting potentially
polluted/monkey-patched parent environment, since remaining jobs
continue to run in the original child process.
docs/ansible.rst:
Add/merge/remove some behaviours/risks.
tests/ansible/integration:
New tests for forking/async.
The strategy is reconstructed for every playbook that is included or
specified on the command line, therefore we can't store the global
Router there without losing all our SSH connections across playbooks.
Ansible's PluginLoader makes up bullshit when it imports a module
(mostly because it has to make up something), therefore we ended up with
duplicate copies of ansible_mitogen loaded: one under
ansible.plugins.*.mitogen, and one under the canonical namespace.
Which broke isinstance().
David Wilson