mutex: Add a logical mutex locking module to help prevent global or per-host race conditions

[aramalipoor]

Work in progress

SUMMARY

We usually need to have a global mutex lock to avoid simultaneous ansible playbooks to run from our bastion machine targeting our cluster.

One example is adding a new node to the cluster, which due to many complex tasks involved must be done only once "per cluster" at a time. This needs a global mutex on the bastion machine to prevent other ansible processes to run the same role/tasks.

Another example would be per-host procedures which don't have internal locks.

Before diving deep into creating a custom module it would be great to have your feedbacks on such a module. Is this a good practice to provide users with a mutex locking module at all? Based on current description in mutex.py in this PR, would this be a useful module?

I intend to use file.py's LockFile and create a lock file on the machine that is running the ansible process.

ISSUE TYPE

• Feature Pull Request

COMPONENT NAME

mutex

Related to issue #31096

Disclaimer: I'm new to python and contributing to Ansible

[ansibot]

The test ansible-test sanity --test boilerplate [explain] failed with 2 errors:

lib/ansible/modules/utilities/logic/mutex.py:0:0: missing: __metaclass__ = type
lib/ansible/modules/utilities/logic/mutex.py:0:0: missing: from __future__ import (absolute_import, division, print_function)

The test ansible-test sanity --test pep8 [explain] failed with 15 errors:

lib/ansible/modules/utilities/logic/mutex.py:21:109: W291 trailing whitespace
lib/ansible/modules/utilities/logic/mutex.py:23:108: W291 trailing whitespace
lib/ansible/modules/utilities/logic/mutex.py:27:73: W291 trailing whitespace
lib/ansible/modules/utilities/logic/mutex.py:32:117: W291 trailing whitespace
lib/ansible/modules/utilities/logic/mutex.py:39:109: W291 trailing whitespace
lib/ansible/modules/utilities/logic/mutex.py:50:111: W291 trailing whitespace
lib/ansible/modules/utilities/logic/mutex.py:51:51: W291 trailing whitespace
lib/ansible/modules/utilities/logic/mutex.py:59:116: W291 trailing whitespace
lib/ansible/modules/utilities/logic/mutex.py:60:110: W291 trailing whitespace
lib/ansible/modules/utilities/logic/mutex.py:66:69: W291 trailing whitespace
lib/ansible/modules/utilities/logic/mutex.py:79:68: W291 trailing whitespace
lib/ansible/modules/utilities/logic/mutex.py:84:71: W291 trailing whitespace
lib/ansible/modules/utilities/logic/mutex.py:126:1: E302 expected 2 blank lines, found 1
lib/ansible/modules/utilities/logic/mutex.py:156:1: E302 expected 2 blank lines, found 1
lib/ansible/modules/utilities/logic/mutex.py:159:1: E305 expected 2 blank lines after class or function definition, found 1

The test ansible-test sanity --test validate-modules [explain] failed with 1 error:

lib/ansible/modules/utilities/logic/mutex.py:0:0: E324 Value for "default" from the argument_spec (False) for "release_on_exit" does not match the documentation (True)

click here for bot help

[acalm]

Please note that #47322 includes a lot of changes and bug fixes to FileLock, you probably want to use that after those changes has been merged. It should(tm) be good to go, waiting for final review from @abadger

…

On Sat, 29 Dec 2018, 16:33 Aram Alipoor ***@***.*** wrote: @bcoca <https://github.com/bcoca> @acalm <https://github.com/acalm> — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#50382 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AQu64HqnluYiAQwAsXJaYnzS0VufQLPZks5u94s_gaJpZM4ZknJs> .

[ansibot]

The test ansible-test sanity --test pep8 [explain] failed with 4 errors:

lib/ansible/modules/utilities/logic/mutex.py:31:73: W291 trailing whitespace
lib/ansible/modules/utilities/logic/mutex.py:130:1: E302 expected 2 blank lines, found 1
lib/ansible/modules/utilities/logic/mutex.py:158:1: E302 expected 2 blank lines, found 1
lib/ansible/modules/utilities/logic/mutex.py:161:1: E305 expected 2 blank lines after class or function definition, found 1

click here for bot help

[ansibot]

@AnderEnder @gregswift @jarv @jhoekx @linuxdynasty @tbielawa

As a maintainer of a module in the same namespace this new module has been submitted to, your vote counts for shipits. Please review this module and add shipit if you would like to see it merged.

click here for bot help