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< Magnum
Revision as of 06:56, 5 May 2015 by P Rivera (talk | contribs) (Before You Begin)

Before You Begin

To familiarize yourself with Magnum, try it out using the information in our Dev Quickstart Guide and Manually Adding Magnum to DevStack Guide. When you are ready to start contributing, you will need to execute an OpenStack CLA. This is required before you can submit reviews to our Magnum Repo. For information about how prepare for contribution, please consult the How To Contribute wiki page.

Sign Up for the OpenStack Development Mailing List

Head on over to OpenStack Dev Mailing List, fill out the fields under "Subscribing to OpenStack-dev" and click Subscribe.

Learn About Gerrit

Be sure to read the Developer's Guide for information about how to submit your commit for review so it can be merged into the Magnum code base.

If you do not have a gerrit username setup or do not remember it, verify and configure it here: https://review.openstack.org/#/settings/

Keep that handy for the "git review -s" command later in the https://wiki.openstack.org/wiki/Magnum/Contributing#Setting_up_your_git_review_settings and https://wiki.openstack.org/wiki/Magnum/Contributing#Set_up_your_local_branch sections below...

You'll also need to upload an SSH public key, specifically for Gerrit: https://review.openstack.org/#/settings/ssh-keys

Setting up your git review settings

New to git? Try the 15-minute high-level interactive Git demo GitHub Demo

Need a git refresher? Download a git reference direct from the source: GitHub Git Cheat Sheet


 git config --global user.name "Firstname Lastname"
 git config --global user.email "your_email@youremail.com"

In the event your launchpad and gerrit usernames are identical:

 git config --global gitreview.username "your_launchpad_username"

In the event your launchpad and gerrit usernames are not identical:

 git config --global gitreview.username "your_gerrit_username"

To check your git configuration:

 git config --list

Installing git-review

On Ubuntu, MacOSx, or most other Unix-like systems, it is as simple as:

 pip install git-review

There are other installation options detailed in the Developer's Guide. You can now check out the Magnum code and begin working on it:

Your first commit

Set up your local branch

 git clone git://git.openstack.org/openstack/magnum
 cd magnum
 git checkout -b [branch name]
 git review -s

If you receive the following error when running the "git review -s" command:

 We don't know where your gerrit is. Please manually create a remote
 named "gerrit" and try again.

Perform the following (substituting <your gerrit username> with your specific gerrit username...):

 git remote add gerrit ssh://<your gerrit username>@review.openstack.org:29418/openstack/magnum.git
 git review -s

If you receive the following error when running the "git review -s" command:

 Agent admitted failure to sign using the key

See this support page: https://help.github.com/articles/error-agent-admitted-failure-to-sign/

Identify bugs

Observe a bug? Report it here: https://launchpad.net/magnum

  1. Click the Report a Bug button.
  2. Enter a Summary in the field and click Next. Here's an example: Stale link to Gerrit Workflow
  3. Review the choices you've been given. If you spot your bug, click on the bug and review its status; proceed to the awesome code section below if there's more to do.. If you do not spot your bug, proceed to the next step.
  4. Click the No, I need to report a new bug button.
  5. Type in a detailed description of the bug in the "Further information" field and click Submit bug report. Here's an example description for our previous example: In doc/source/dev/dev-quickstart.rst the link to the Gerrit workflow is incorrect. It should be: http://docs.openstack.org/infra/manual/developers.html

Write some awesome code

At this point can write your code and push it to Gerrit for review.

 git add <list of files you added/changed>

If you submitted a bug in the previous section, be sure to add the bug link in the commit message.

Each commit line should conform with the OpenStack style guidelines. Some highlights:

  1. The first line of the commit message should be <=50 characters.
  2. The subsequent lines can be <= 78 characters.
  3. Lines 2 onward are a blank line followed by a more verbose description of the first commit line (as needed).
  4. The last commit line needs to link to either a blueprint or bug/task ticket number.
  5. There should be no whitespace at the end of all lines.

For the example case:

 Adjust Gerrit workflow Link
 <blank line>
 The Gerrit workflow link in the previous version is no longer valid.
 This patch updates documentation to the current link.
 <blank line>
 Closes-bug: <bug/task ticket number>


 git commit -a
 git review -v --draft

Once you are happy with your code and want it to be reviewed you want to convert it from a Draft. "Sign In" at https://review.openstack.org/ and after verifying the review yourself hit the "Publish" button on the page.

If you know you are ready for others to review your code, you can skip the draft step and just do:

git review -v

By this point, your code will be reviewed by the Openstack automatic testing frameworks and, potentially, your peers on the project.

If you want to revise your patchset in the review system in response to feedback, make your changes, then use:

git commit -a --amend
git review -v

Upon approval of the review your code will be automatically merged.

How to Resolve Merge Conflicts

If another patch changes the same line of code as your patch, and it gets merged before yours, your patch may get a patch in merge conflict status in red. If that happens, here is how you can resolve it. You will need the patch number from the Gerrit URL https://review.openstack.org/NNNNN to make your rebase a revision of the previous review.

git clone https://github.com/openstack/magnum
cd magnum
git review -d NNNNN
git rebase master

Now edit all files with merge conflicts to resolve them by making the code look the way it should both with the recently merged code, and your own. Then git add each of the files you edited.

git add path/to/file/you/edited
git rebase --continue
git review -v

That will resubmit your patch with the original commit message, and the rebased code with your merge fix as a new patch set.


The OpenStack CI system uses the concept of core reviewers. These are individuals who have consistently reviewed code for the project, and helped over a considerable period of time to improve the quality and consistency of what we merge into the code base. Project contributors will feel that this reviewer is a positive influence on the team and that they maintain the values and traditions of the OpenStack development community.


Existing core reviewers may nominate new ones in an ML thread. Consent among the current reviewers shall result in the declaration of the new core reviewer by the PTL. Lack of unanimous consent shall be carefully considered, and a final decision informed by input from from active team members shall be made by the PTL. Core reviewers who are judged by their peers in the core review group to fall short of the expectations for contribution of a core reviewer may be nominated for return to regular reviewer status.

Patches require a core reviewer to mark a review as "Approved" before they are merged.

Review Guidelines

Code Approval for Merge

  • For Approval, two core reviewers shall supply a +2.

Continuing Someone Else's Contribution

  • If a patch submitted by one contributor is picked up and completed by another contributor, special handling of the resolution should be used.

Advice for Reviewers

  • A -1 vote is an opportunity to make our code better before it is merged. Please do your best to make helpful, actionable -1 votes.
  • Avoid the temptation to blindly +1 code without reviewing it in sufficient detail to form an opinion.
  • When voting -1 on a patch, it means that you want the submitter to make a revision in accordance with your feedback before core reviewers should consider this code for merge.
  • If you ask a question, you should vote 0 unless you anticipate that the answer to that question is likely to cause you to vote against the patch without further revisions.
  • If you use a -1 vote for a question, and the contributor answers the question, please respond acknowledging the question. Either change your vote or follow up with additional rationale for why this should remain a -1 comment.
  • A -2 vote is a veto by a single core reviewer. It is sticky. That means that even if you revise your patch, that vote will persist. To allow your patch to merge, that same reviewer must clear the -2 vote first. This vote is used when you have contributed something that is not in alignment with the current project vision, or is implemented in a way that can not be accepted. For example, security concerns that a core reviewer wants to individually re-evaluate before allowing the contribution to continue. It can also be used as a way to halt further gate testing of a patch, if something is included that may break the gate. It works even after a 2*+2,+A approval for merge, but before the patch reaches MERGED state.
  • To avoid a -2 vote, discuss your plans with the development team prior to writing code, and post a WIP (workflow-1) patch while you are working on it, and ask for input before you submit it for merge review.