The controller must know the ID of the forked child in order to
propagate dependencies to it, so forking+starting the module run cannot
happen entirely on the target, without some additional mechanism to
wait-and-repropagate the deps as they arrive on the target.
Rework things so that init_child() also handles starting the fork parent,
and returns it along with the context's home directory in a single round
trip.
Now master knows the identity of the fork parent, it can directly create
fork children and call run_module_async() in them. This necessitates 2
roundtrips to start an asynchronous task.
This whole thing sucks and entirely needs simplified, but for now things
almost work, so keeping it.
connection.py:
* Expect ContextService to return the entire dict return value of
init_child(). Store the fork_contxt from the return value.
planner.py:
* Rework Planner to store the invocation as an instance attribute, to
simplify method calls.
* Add Planner.get_push_files() and Planner.get_module_deps().
* Add _propagate_deps() which takes a Planner and ensures the deps it
describes are sent to a (non forked or forked) context.
* Move async task logic out of target.py and into invoke() /
_invoke_*().
process.py:
* Services no longer need references to each other. planner.py handles
sending module deps with one extra RPC.
services.py:
* Return "init_child_result" key instead of simple "home_dir" key.
* Get rid of dep propagation from ModuleDepService, it lives in
planner.py now.
target.py:
* Get rid of async task start logic, lives in planner.py now.
planner.py:
* Rather than grant FileService access to a file for children, use
PushFileService to trigger deduplicating send of the file through
the hierarchy immediately.
* Send the complete list of Ansible module imports to the target so
runner.py knows which files and scripts must be loaded via
PushFileService prior to detaching.
runner.py:
* Teach NewStyleRunner to use the full module map to block until
everything is loaded prior to detach().
target.py:
* Delete old _get_file(), replace get_file() with get_small_file()
which uses PushFileService instead.
Closes#186
For lack of a better place to keep the client function, make it a
classmethod of FileService itself for now.
The old _get_file() is removed in a subsequent commit.
It's not simple without executing a module to determine whether the
above refers to a submodule of a package, or an object defined within a
module.
Therefore detect when resolution of a child module yields the same path
as the parent, and ignore the result.
For "ansible -m setup" over a 25ms link, avoids 65 roundtrips and
reduces runtime from 5.7s to 4.1s (-28%).
For "ansible -m setup" over a simulated 250 ms link, reduces runtime
from m27.015s to 0m8.254s (-69%).
This may come back to bite later, but in the meantime it avoids shipping
up to 12KiB of junk metadata for every single task invocation.
For detachment (aka. async), we must ensure the target has two types of
preloads completed (modules and module_utils files) before detaching.
The OpenShift installer modifies /etc/resolv.conf then tests the new
resolver configuration, however, there was no mechanism to reload
resolv.conf in our reuseable interpreter.
https://github.com/openshift/openshift-ansible/blob/release-3.9/roles/openshift_web_console/tasks/install.yml#L137
This inserts an explicit call to res_init() for every new style
invocation, with an approximate cost of ~1usec on Linux since glibc
verifies resolv.conf has changed before reloading it.
There is little to be done for users of the thread-safe resolver APIs,
their state is hidden from us. If bugs like that manifest, whack-a-mole
style 'del sys.modules[thatmod]' patches may suffice.
Traced git log all the way back to beginning of time, and checked
Ansible versions starting Jan 2016. Zero clue where this came from, but
the convention suggests it came from Ansible at some point.
While adding support for non-new style module types, NewStyleRunner
began writing modules to a temporary file, and sys.argv was patched to
actually include the script filename. The argv change was never required
to fix any particular bug, and a search of the standard modules reveals
no argv users. Update argv[0] to be '', like an interactive interpreter
would have.
While fixing #210, new style runner began setting __file__ to the
temporary file path in order to allow apt.py to discover the Ansiballz
temporary directory. 5 out of 1,516 standard modules follow this
pattern, but in each case, none actually attempt to access __file__,
they just call dirname on it. Therefore do not write the contents of
file, simply set it to the path as it would exist, within a real
temporary directory.
Finally move temporary directory creation out of runner and into target.
Now a single directory exists for the duration of a run, and is emptied
by runner.py as necessary after each task invocation.
This could be further extended to stop rewriting non-new-style modules
in a with_items loop, but that's another step.
Finally the last bullet point in the documentation almost isn't a lie
again.
Ideally it would be possible to specify a callback function, but this is
not possible for proxied connections. So simply provide the 3 most
useful modes, defaulting to the most secure.
Closes#127. Closes#134.
David Wilson