Starting in Pike TripleO sets the ansible fork count to maximize the number of concurrent ceph-ansible processes [0] by setting it equal to the number of nodes needing to be configured up to 100. However, if the undercloud doesn't have enough memory, then this setting cause the undercloud to run out of RAM [1]. The user should be able to easily override this parameter and not use the formula.
[0] https://github.com/openstack/tripleo-common/blob/fa0b9f52080580b7408dc6f5f2da6fc1dc07d500/workbooks/ceph-ansible.yaml#L25
[1]
2017-12-13 04:05:53,887 p=7259 u=mistral | ERROR! Unexpected Exception, this is probably a bug: [Errno 12] Cannot allocate memory │····················
2017-12-13 04:05:53,893 p=7259 u=mistral | to see the full traceback, use -vvv │····················
2017-12-13 04:05:58,541 p=7259 u=mistral | the full traceback was: │····················
│····················
Traceback (most recent call last): │····················
File "/bin/ansible-playbook", line 106, in <module> │····················
exit_code = cli.run() │····················
File "/usr/lib/python2.7/site-packages/ansible/cli/playbook.py", line 130, in run │····················
results = pbex.run() │····················
File "/usr/lib/python2.7/site-packages/ansible/executor/playbook_executor.py", line 154, in run │····················
result = self._tqm.run(play=play) │····················
File "/usr/lib/python2.7/site-packages/ansible/executor/task_queue_manager.py", line 302, in run │····················
play_return = strategy.run(iterator, play_context) │····················
File "/usr/lib/python2.7/site-packages/ansible/plugins/strategy/linear.py", line 277, in run │····················
self._queue_task(host, task, task_vars, play_context) │····················
File "/usr/lib/python2.7/site-packages/ansible/plugins/strategy/__init__.py", line 222, in _queue_task │····················
worker_prc.start() │····················
File "/usr/lib64/python2.7/multiprocessing/process.py", line 130, in start │····················
self._popen = Popen(self) │····················
File "/usr/lib64/python2.7/multiprocessing/forking.py", line 121, in __init__ │····················
self.pid = os.fork() │····················
OSError: [Errno 12] Cannot allocate memory
Fix proposed to branch: master
Review: https:/