ironic/doc/source/contributor/code-contribution-guide.rst

.. _code-contribution-guide:

=======================
Code Contribution Guide
=======================

This document provides some necessary points for developers to consider when
writing and reviewing Ironic code. The checklist will help developers get
things right.

Getting Started
===============

If you're completely new to OpenStack and want to contribute to the ironic
project, please start by familiarizing yourself with the `Infra Team's Developer
Guide <https://docs.openstack.org/infra/manual/developers.html>`_. This will
help you get your accounts set up in Launchpad and Gerrit, familiarize you with
the workflow for the OpenStack continuous integration and testing systems, and
help you with your first commit.

LaunchPad Project
-----------------

Most of the tools used for OpenStack require a launchpad.net ID for
authentication.

.. seealso::

   * https://launchpad.net
   * https://launchpad.net/ironic

Related Projects
----------------

There are several projects that are tightly integrated with ironic and which are
developed by the same community.

.. seealso::

   * https://launchpad.net/bifrost
   * https://launchpad.net/ironic-inspector
   * https://launchpad.net/ironic-lib
   * https://launchpad.net/ironic-python-agent
   * https://launchpad.net/python-ironicclient
   * https://launchpad.net/python-ironic-inspector-client

Project Hosting Details
-----------------------

Bug tracker
    https://bugs.launchpad.net/ironic

Mailing list (prefix Subject line with ``[ironic]``)
    http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev

Wiki
    https://wiki.openstack.org/Ironic

Code Hosting
    https://git.openstack.org/cgit/openstack/ironic

Code Review
    https://review.openstack.org/#/q/status:open+project:openstack/ironic,n,z

Adding New Features
===================

Starting with the Mitaka development cycle, Ironic tracks new features using
RFEs (Requests for Feature Enhancements) instead of blueprints. These are bugs
with 'rfe' tag, and they should be submitted before a spec or code is proposed.
When a member of `ironic-drivers launchpad team
<https://launchpad.net/~ironic-drivers/+members>`_ decides that the proposal
is worth implementing, a spec (if needed) and code should be submitted,
referencing the RFE bug. Contributors are welcome to submit a spec and/or code
before the RFE is approved, however those patches will not land until the RFE
is approved.

Feature Submission Process
--------------------------

#. Submit a bug report at https://bugs.launchpad.net/ironic/+filebug.
   There are two fields that must be filled: 'summary' and
   'further information'. The 'summary' must be brief enough to fit in one
   line: if you can’t describe it in a few words it may mean that you are
   either trying to capture more than one RFE at once, or that you are having
   a hard time defining what you are trying to solve at all.

#. Describe the proposed change in the 'further information' field. The
   description should provide enough details for a knowledgeable developer to
   understand what is the existing problem in the current platform that needs
   to be addressed, or what is the enhancement that would make the platform
   more capable, both from a functional and a non-functional standpoint.

#. Submit the bug, add an 'rfe' tag to it and assign yourself or whoever is
   going to work on this feature.

#. As soon as a member of the ironic-drivers team acknowledges the bug, it
   will be moved into the 'Triaged' state. The importance will be set to
   'Wishlist' to signal the fact that the report is indeed a feature and there
   is no severity associated to it. Discussion about the RFE, and whether to
   approve it, happens in bug comments while in the 'Triaged' state.

#. The ironic-drivers team will evaluate the RFE and may advise the submitter
   to file a spec in ironic-specs to elaborate on the feature request, in case
   the RFE requires extra scrutiny, more design discussion, etc. For the spec
   submission process, please see the `Ironic Specs Process`_.

#. If a spec is not required, once the discussion has happened and there is
   positive consensus among the ironic-drivers team on the RFE, the RFE is
   'approved', and its tag will move from 'rfe' to 'rfe-approved'. This means
   that the feature is approved and the related code may be merged.

#. If a spec is required, the spec must be submitted (with the bug properly
   referenced as 'Partial-Bug' in the commit message), reviewed, and merged
   before the RFE will be 'approved' (and the tag changed to 'rfe-approved').

#. The bug then goes through the usual process -- first to 'In progress' when
   the spec/code is being worked on, then 'Fix Released' when it is
   implemented.

#. If the RFE is rejected, the ironic-drivers team will move the bug to
   "Won't Fix" status.

Change Tracking
---------------

When working on an RFE, please be sure to tag your commits properly:
"Partial-Bug: #xxxx" or "Related-Bug: #xxxx" for intermediate commits for the
feature, and "Closes-Bug: #xxxx" for the final commit. It is also helpful to
set a consistent review topic, such as "bug/xxxx" for all patches related to
the RFE.

If the RFE spans across several projects (e.g. ironic and python-ironicclient),
but the main work is going to happen within ironic, please use the same bug for
all the code you're submitting, there is no need to create a separate RFE in
every project.

.. note:: Currently the Ironic bug tracker is managed by the open
          'ironic-bugs' team, not the ironic-drivers team. This means that
          anyone may edit bug details, and there is room to game the system
          here. **RFEs may only be approved by members of the ironic-drivers
          team**.

Managing Change Sets
--------------------

If you would like some help, or if you (or some members of your team)
are unable to continue working on the feature, updating and
maintaining the changes, please let the rest of the ironic community
know. You could leave a comment in one or more of the
changes/patches, bring it up in IRC, the weekly meeting,
or on the OpenStack development email list.
Communicating this will make other contributors aware of the
situation and allow for others to step forward and volunteer to
continue with the work.

In the event that a contributor leaves the community, do not expect
the contributor's changes to be continued unless someone volunteers
to do so.

Timeline Expectations
=====================

As with any large project, it does take time for features and changes to be
merged in any of the project repositories. This is largely due to limited
review bandwidth coupled with varying reviewer priorities and focuses.

When establishing an understanding of complexity, the following things should
be kept in mind.

* Generally, small and minor changes can gain consensus and merge fairly
  quickly. These sorts of changes would be: bug fixes, minor documentation
  updates, follow-up changes.

* Medium changes generally consist of driver feature parity changes,
  where one driver is working to match functionality of another driver.

  * These changes generally only require an RFE for the purposes of
    tracking and correlating the change.
  * Documentation updates are expected to be submitted with or immediately
    following the initial change set.

* Larger or controversial changes generally take much longer to merge.
  This is often due to the necessity of reviewers to gain additional
  context and for change sets to be iterated upon to reach a state
  where there is consensus. These sorts of changes include: database,
  object, internal interface additions, RPC, rest API changes.

  * These changes will very often require specifications to reach
    consensus, unless there are pre-existing patterns or code already
    present.
  * These changes may require many reviews and iterations, and can
    also expect to be impacted by merge conflicts as other code or
    features are merged.
  * These changes must typically be split into a series of changes.
    Reviewers typically shy away from larger single change sets due
    to increased difficulty in reviewing.
  * Do not expect any API or user-visible data model changes to merge
    after the API client freeze. Some substrate changes may merge if
    not user visible.

* You should expect complex features, such as cross-project features
  or integration, to take longer than a single development cycle to land.

  * Building consensus is vital.
  * Often these changes are controversial or have multiple
    considerations that need to be worked through in the specification
    process, which may cause the design to change. As such, it may
    take months to reach consensus over design.
  * These features are best broken into larger chunks and tackled
    in an incremental fashion.

Live Upgrade Related Concerns
=============================

See :doc:`/contributor/rolling-upgrades`.

Driver Internal Info
====================
The ``driver_internal_info`` node field was introduced in the Kilo release. It allows
driver developers to store internal information that can not be modified by end users.
Here is the list of existing common and agent driver attributes:

* Common attributes:

  * ``is_whole_disk_image``: A Boolean value to indicate whether the user image contains ramdisk/kernel.
  * ``clean_steps``: An ordered list of clean steps that will be performed on the node.
  * ``instance``: A list of dictionaries containing the disk layout values.
  * ``root_uuid_or_disk_id``: A String value of the bare metal node's root partition uuid or disk id.
  * ``persistent_boot_device``: A String value of device from ``ironic.common.boot_devices``.
  * ``is_next_boot_persistent``: A Boolean value to indicate whether the next boot device is
    ``persistent_boot_device``.

* Agent driver attributes:

  * ``agent_url``: A String value of IPA API URL so that Ironic can talk to IPA
    ramdisk.
  * ``hardware_manager_version``: A String value of the version of the hardware
    manager in IPA ramdisk.
  * ``target_raid_config``: A Dictionary containing the target RAID
    configuration. This is a copy of the same name attribute in Node object.
    But this one is never actually saved into DB and is only read by IPA ramdisk.

.. note::

    These are only some fields in use. Other vendor drivers might expose more ``driver_internal_info``
    properties, please check their development documentation and/or module docstring for details.
    It is important for developers to make sure these properties follow the precedent of prefixing their
    variable names with a specific interface name (e.g., ilo_bar, drac_xyz), so as to minimize or avoid
    any conflicts between interfaces.


Ironic Specs Process
====================

Specifications must follow the template which can be found at
`specs/template.rst <https://git.openstack.org/cgit/openstack/ironic-specs/tree/
specs/template.rst>`_, which is quite self-documenting. Specifications are
proposed by adding them to the `specs/approved` directory, adding a soft link
to it from the `specs/not-implemented` directory, and posting it for
review to Gerrit. For more information, please see the `README <https://git.
openstack.org/cgit/openstack/ironic-specs/tree/README.rst>`_.

The same `Gerrit process
<https://docs.openstack.org/infra/manual/developers.html>`_ as with source code,
using the repository `ironic-specs <https://git.openstack.org/cgit/openstack/
ironic-specs/>`_, is used to add new specifications.

All approved specifications are available at:
https://specs.openstack.org/openstack/ironic-specs. If a specification has
been approved but not completed within one or more releases since the
approval, it may be re-reviewed to make sure it still makes sense as written.

Ironic specifications are part of the `RFE (Requests for Feature Enhancements)
process <#adding-new-features>`_.
You are welcome to submit patches associated with an RFE, but they will have
a -2 ("do not merge") until the specification has been approved. This is to
ensure that the patches don't get accidentally merged beforehand. You will
still be able to get reviewer feedback and push new patch sets, even with a -2.
The `list of core reviewers <https://review.openstack.org/#/admin/groups/352,
members>`_ for the specifications is small but mighty. (This is not
necessarily the same list of core reviewers for code patches.)

Changes to existing specs
-------------------------

For approved but not-completed specs:

- cosmetic cleanup, fixing errors, and changing the definition of a feature
  can be done to the spec.

For approved and completed specs:

- changing a previously approved and completed spec should only be done
  for cosmetic cleanup or fixing errors.
- changing the definition of the feature should be done in a new spec.


Please see the `Ironic specs process wiki page <https://wiki.openstack.org/
wiki/Ironic/Specs_Process>`_ for further reference.