Make ilo drivers standalone in ironic by removing swift dependency

https://blueprints.launchpad.net/ironic/+spec/remove-swift-dependency-for-ilo-drivers

This spec proposes to remove hard dependency on swift for ilo virtual media drivers. There are standalone use-cases of Ironic (like bifrost) which are capable of deploying nodes without requiring other Openstack services. With this the ilo virtual media drivers can also work standalone similar to other drivers in ironic.

Problem description

Today the ilo drivers (iscsi_ilo and agent_ilo) require swift to host the images like boot_iso (from which the instance boots) and floppy images (used for passing parameters to deploy ramdisk).

Proposed change

The ilo drivers (iscsi_ilo and agent_ilo) can use a web server to host the images required. Swift would be used as a default backend to host boot ISO and floppy images for these drivers.

  • The automatic boot_iso created (as required by iscsi_ilo for booting up the instance) and floppy images (as required by both agent_ilo and iscsi_ilo for passing parameters to deploy ramdisk) during deploy process, will be hosted on swift or http web server as per the config variable under [ilo] in ironic.conf:

    use_http_web_server_for_images=True
    

    The default value would be False and will default to use swift.

  • User needs to manually configure the webserver, and add the config options in ironic.conf under deploy as:

    http_server_root = /opt/stack/ironic/data/httpboot
    http_server_url = http://10.10.1.30/httpboot

    Since the same config variables exists under [pxe] and are required by ilo drivers to be able to run standalone, we can deprecate the same in [pxe] and move it under [deploy]. The above values to the config variables are just an example. They will continue to have the default value as the current config variables http_url and http_root.

  • To add the functionality of take_over() to ilo drivers. This is to enable a case when the conductor node goes down and other conductor takes over the baremetal. The take_over() will be implemented to do regenerate in following scenarios:

    • for wait_call_back state: implement regeneration of floppy images.
    • for active state : implement regeneration of boot ISO.

Alternatives

None.

Data model impact

None.

State Machine Impact

None.

REST API impact

None.

Client (CLI) impact

None.

RPC API impact

None.

Driver API impact

None.

Nova driver impact

None.

Security impact

None.

Other end user impact

None.

Scalability impact

None.

Performance Impact

None.

Other deployer impact

The http web server configuration is out of scope of ironic but it should be configured on every conductor node. User needs to manually configure the web server, and add the config options in ironic.conf under deploy as:

http_server_root = /opt/stack/ironic/data/httpboot
http_server_url = http://10.10.1.30/httpboot

Since the same config variables exists under [pxe] and is required by ilo drivers to be able to run standalone, we can deprecate the same in [pxe] and move it under [deploy].

Developer impact

None.

Implementation

Assignee(s)

Primary assignee:
agarwalnisha1980

Work Items

  • To modify ipxe to use config variables from [deploy] section.
  • To enable support for using webserver in ilo drivers.
  • To implement take_over() for ilo_drivers for use_web_server=True

Dependencies

None.

Testing

  • Mocked unit tests would be added.
  • Functional tests would be done to ensure that the deploy works fine for ilo drivers with swift as backend or http webserver as backend.

Upgrades and Backwards Compatibility

The ilo drivers will continue to work with swift as backend. The iPXE code will continue to work for config options in either of the section.

Documentation Impact

It is required to be documented.

References

None.