Dmitry Tantsur (Principal Software Engineer, Red Hat)
Cleaning is a process of preparation a node for carrying tenant loads.
Common examples are wiping hard drives, updating firmware, resetting BIOS variables, etc.
It is run every time before nodes get available for deployment.
Ironic provision states are organized into a formal state machine: states diagram.
Nodes enter cleaning on the way from manageable or deleting to available.
There is also a way to initiate manual cleaning via API.
The boot interface prepare_ramdisk is used again, the same as with deployment.
Nearly the same procedure is used for neutron networking: ironic/drivers/modules/network/neutron.py.
As with deployment, clean steps are run in response to IPA heart beats: ironic/drivers/modules/agent_base_vendor.py.
Here we either run out of further steps, or encounter an asynchronous step, and move back to clean wait.
Clean steps are actions to run during cleaning. They can be provided by power, management, deploy and raid interfaces.
Clean steps have priority and "abortable" flag. For manual cleaning, clean steps can also have arguments.
With IPA-based deploy, clean steps can also be provided by IPA hardware managers.
Priority defines the order the steps are run. Priority 0 means the step will only work with manual cleaning explained later.
More advanced interfaces (e.g. IPA-based deploy) can override get_clean_steps.
The IPA-based deploy interfaces also load clean steps from the ramdisk. For this to be possible, Ironic starts the ramdisk unconditionally before starting cleaning.
The clean steps are cached after the first heart beat, to not block get_clean_steps later: ironic/drivers/modules/agent_base_vendor.py.
Then Ironic can run any of them via another IPA API call: ironic_python_agent/extensions/clean.py.
Manual cleaning is a way to run driver-specific actions on manageable nodes. The mechanism is the same as with automated cleaning described previously.
It is not limited to actually cleaning nodes. For example, RAID is implemented through it.
Manual cleaning is started by invoking clean provisioning action and providing a list of clean steps to run and their arguments.
Ironic can build RAID on nodes in advance (when nodes are in manageable state).
The raid interface validates and processes the requested RAID layout: ironic/drivers/raid_config_schema.json.
Then the actual configuration happens on manual cleaning, for example for drac: ironic/drivers/modules/drac/raid.py.