I had a long call with Jeroen today about how to manage the PXE config writing Tasks.
There are quite a few problems, but to summarise them: 1/ Celery tasks are not currently sent only on transaction commit 2/ Writing PXE configs will eventually happen on a different worker to the boot Task so we need to worry about serialization We think we can solve the first problem by using a package called django- celery-transactions which installs its own middleware to handle task creation on commit. Regarding the second point, this is a little subtle. We've decided to change the way PXE configs are maintained on disk. Initially we thought that we'd write them on every change that necessitates a new config but this is unnecessary and complicates other parts of the webapp (as recently discussed on a merge proposal). So, the plan is to create a job to write PXE configs: * just before booting (observing the netboot flag) * when deleting a MAC address associated with a node (it's not something that can be synced later), we delete the file for that MAC * when decommissioning a node, we delete all its PXE config files What this means is that we now have the problem of serializing two Tasks, possibly across different workers: writing configs and then booting. Hopefully we can solve this by using Celery's subtasks with callbacks. If anyone has any questions or concerns, please reply now! J -- Mailing list: https://launchpad.net/~maas-devel Post to : [email protected] Unsubscribe : https://launchpad.net/~maas-devel More help : https://help.launchpad.net/ListHelp
