ironic-python-agent/doc/source/admin/how_it_works.rst

How it works

Integration with Ironic

Compatible Deploy Drivers

Agent Deploy Driver

IPA works with the agent Deploy driver in Ironic to provision nodes. Starting with ironic-python-agent running on a ramdisk on an unprovisioned node, Ironic makes API calls to ironic-python-agent to provision the machine. This allows for greater control and flexibility of the entire deployment process.

PXE Deploy Driver

IPA may also be used with the original Ironic pxe driver as of the Kilo OpenStack Ironic release.

Configuring Deploy Drivers

For information on how to install and configure Ironic drivers, including drivers for IPA, see the Ironic drivers documentation¹.

Lookup

On startup, the agent performs a lookup in Ironic to determine its node UUID by sending a hardware profile to the Ironic lookup endpoint: /v1/lookup.

Heartbeat

After successfully looking up its node, the agent heartbeats via /v1/heartbeat/{node_ident} every N seconds, where N is the Ironic conductor's agent.heartbeat_timeout value multiplied by a number between .3 and .6.

For example, if your conductor's ironic.conf contains:

[agent]
heartbeat_timeout = 60

IPA will heartbeat between every 20 and 36 seconds. This is to ensure jitter for any agents reconnecting after a network or API disruption.

After the agent heartbeats, the conductor performs any actions needed against the node, including querying status of an already run command. For example, initiating in-band cleaning tasks or deploying an image to the node.

Inspection

IPA can conduct hardware inspection on start up and post data to the Ironic Inspector. Edit your default PXE/iPXE configuration or IPA options baked in the image, and set ipa-inspection-callback-url to the full endpoint of Ironic Inspector, for example:

ipa-inspection-callback-url=http://IP:5050/v1/continue

Make sure your DHCP environment is set to boot IPA by default.

Hardware Inventory

IPA collects various hardware information using its Hardware Managers <../contributor/hardware_managers>, and sends it to Ironic on lookup and to Ironic Inspector on Inspection.

The exact format of the inventory depends on the hardware manager used. Here is the basic format expected to be provided by all hardware managers. The inventory is a dictionary (JSON object), containing at least the following fields:

cpu

CPU information: model_name, frequency, count, architecture and flags.

memory

RAM information: total (total size in bytes), physical_mb (physically installed memory size in MiB, optional).

Note

The difference is that the latter includes the memory region reserved by the kernel and is always slightly bigger. It also matches what the Nova flavor would contain for this node and thus is used by the inspection process instead of total.

bmc_address

IP address of the node's BMC (aka IPMI address), optional.

disks

list of disk block devices with fields: name, model, size (in bytes), rotational (boolean), wwn, serial, vendor, wwn_with_extension, wwn_vendor_extension, hctl and by_path (the full disk path, in the form /dev/disk/by-path/<rest-of-path>).

interfaces

list of network interfaces with fields: name, mac_address, ipv4_address, lldp, vendor, product, and optionally biosdevname(BIOS given NIC name). If configuration option collect_lldp is set to True the lldp field will be populated by a list of type-length-value(TLV) fields retrieved using the Link Layer Discovery Protocol (LLDP).

system_vendor

system vendor information from SMBIOS as reported by dmidecode: product_name, serial_number and manufacturer.

boot

boot information with fields: current_boot_mode (boot mode used for the current boot - BIOS or UEFI) and pxe_interface (interface used for PXE booting, if any).

References

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1. Enabling Drivers - https://docs.openstack.org/ironic/latest/admin/drivers/ipa.html↩︎