system-config/doc/source/gerrit.rst

:title: Gerrit

.. _gerrit:

Gerrit
######

Gerrit is the code review system used by the OpenStack project.  For a
full description of how the system fits into the OpenStack workflow,
see `the GerritJenkinsGit wiki article
<https://wiki.openstack.org/wiki/GerritJenkinsGit>`_.

This section describes how Gerrit is configured for use in the
OpenStack project and the tools used to manage that configuration.

At a Glance
===========

:Hosts:
  * http://review.openstack.org
  * http://review-dev.openstack.org
:Puppet:
  * :file:`modules/gerrit`
  * :file:`modules/openstack_project/manifests/review.pp`
  * :file:`modules/openstack_project/manifests/review_dev.pp`
:Configuration:
  * :file:`modules/openstack_project/templates/review.projects.yaml.erb`
:Projects:
  * http://code.google.com/p/gerrit/
:Bugs:
  * http://bugs.launchpad.net/openstack-ci
  * http://code.google.com/p/gerrit/issues/list
:Resources:
  * `Gerrit Documentation <https://review.openstack.org/Documentation/index.html>`_

Installation
============

Gerrit is installed and configured by Puppet, including specifying the
exact Java WAR file that is used.  See :ref:`sysadmin` for how Puppet
is used to manage OpenStack infrastructure systems.

Gerrit Configuration
--------------------

Most of Gerrit's configuration is in configuration files or Git
repositories (and in our case, managed by Puppet), but a few items
must be configured in the database.  The following is a record of
these changes:

Add "Approved" review type to gerrit:

.. code-block:: mysql

  mysql -u root -p
  use reviewdb;
  insert into approval_categories values ('Approved', 'A', 2, 'MaxNoBlock', 'N', 'APRV');
  insert into approval_category_values values ('No score', 'APRV', 0);
  insert into approval_category_values values ('Approved', 'APRV', 1);
  update approval_category_values set name = "Looks good to me (core reviewer)" where name="Looks good to me, approved";

Expand "Verified" review type to -2/+2:

.. code-block:: mysql

  mysql -u root -p
  use reviewdb;
  update approval_category_values set value=2
    where value=1 and category_id='VRIF';
  update approval_category_values set value=-2
    where value=-1 and category_id='VRIF';
  insert into approval_category_values values
    ("Doesn't seem to work","VRIF",-1),
    ("Works for me","VRIF","1");

Reword the default messages that use the word Submit, as they imply that
we're not happy with people for submitting the patch in the first place:

.. code-block:: mysql

  mysql -u root -p
  use reviewdb;
  update approval_category_values set name="Do not merge"
    where category_id='CRVW' and value=-2;
  update approval_category_values
    set name="I would prefer that you didn't merge this"
    where category_id='CRVW' and value=-1;

Add information about the CLA:

.. code-block:: mysql

  insert into contributor_agreements values (
  'Y', 'Y', 'Y', 'ICLA',
  'OpenStack Individual Contributor License Agreement',
  'static/cla.html', 2);

Groups
------

A number of system-wide groups are configured in Gerrit.  These
include `Project Bootstrappers` which grants all the permissions
needed to set up a new project.  Normally the OpenStack Project
Creater account is the only member of this group, but members of the
`Administrators` group may temporarily add themselves in order to
correct problems with automatic project creation.

The `External Testing Tools` group is used to grant +/-1 Verified
access to external testing tools.


GitHub Integration
==================

Gerrit replicate to GitHub by pushing to a standard Git remote.  The
GitHub projects are configured to allow only the Gerrit user to push.

Pull requests can not be disabled for a project in Github, so instead
we have a script that runs from cron to close any open pull requests
with instructions to use Gerrit.

These are both handled automatically by :ref:`jeepyb`.


Auto Review Expiry
==================

Puppet automatically installs a daily cron job called ``expire-old-reviews``
onto the gerrit servers.  This script follows two rules:

 #. If the review hasn't been touched in 2 weeks, mark as abandoned.
 #. If there is a negative review and it hasn't been touched in 1 week, mark as
    abandoned.

If your review gets touched by either of these rules it is possible to
unabandon a review on the gerrit web interface.

This process is managed by the :ref:`jeepyb` openstack-infra project.

Gerrit IRC Bot
==============

Gerritbot consumes the Gerrit event stream and announces relevant
events on IRC.  :ref:`gerritbot` is an openstack-infra project and is
also available on Pypi.


Launchpad Bug Integration
=========================

In addition to the hyperlinks provided by the regex in gerrit.config,
we use a Gerrit hook to update Launchpad bugs when changes referencing
them are applied.  This is managed by the :ref:`jeepyb`
openstack-infra project.


New Project Creation
====================

Gerrit project creation is now managed through changes to the
openstack-infra/config repository.  :ref:`jeepyb` handles
automatically creating any new projects defined in the configuration
files.

Local Git Replica
=================

Gerrit replicates all repos to a local directory so that Apache can
serve the anonymous http requests out directly.  This is automatically
configured by :ref:`jeepyb`.

.. _acl:

Access Controls
===============

High level goals:

#. Anonymous users can read all projects.
#. All registered users can perform informational code review (+/-1)
   on any project.
#. Jenkins can perform verification (blocking or approving: +/-1).
#. All registered users can create changes.
#. The OpenStack Release Manager and Jenkins can tag releases (push
   annotated tags).
#. Members of $PROJECT-core group can perform full code review
   (blocking or approving: +/- 2), and submit changes to be merged.
#. Members of Release Managers (Release Manager and delegates), and
   $PROJECT-milestone (PTL and release minded people) exclusively can
   perform full code review (blocking or approving: +/- 2), and submit
   changes to be merged on milestone-proposed branches.
#. Full code review (+/- 2) of API projects should be available to the
   -core group of the corresponding implementation project as well as to
   the OpenStack Documentation Coordinators.
#. Full code review of stable branches should be available to the
   -core group of the project as well as the openstack-stable-maint
   group.
#. Drivers (PTL and delegates) of client library projects should be
   able to add tags (which are automatically used to trigger
   releases).

To manage API project permissions collectively across projects, API
projects are reparented to the "API-Projects" meta-project instead of
"All-Projects".  This causes them to inherit permissions from the
API-Projects project (which, in turn, inherits from All-Projects).

These permissions try to achieve the high level goals::

  All Projects (metaproject):
    refs/*
      read: anonymous
      push annotated tag: release managers, ci tools, project bootstrappers
      forge author identity: registered users
      forge committer identity: project bootstrappers
      push (w/ force push): project bootstrappers
      create reference: project bootstrappers, release managers
      push merge commit: project bootstrappers

    refs/for/refs/*
      push: registered users

    refs/heads/*
      label code review:
        -1/+1: registered users
        -2/+2: project bootstrappers
      label verified:
        -2/+2: ci tools
        -2/+2: project bootstrappers
        -1/+1: external tools
      label approved 0/+1: project bootstrappers
      submit: ci tools
      submit: project bootstrappers

    refs/heads/milestone-proposed
      label code review (exclusive):
        -2/+2 Release Managers
        -1/+1 registered users
      label approved (exclusive): 0/+1: Release Managers
      owner: Release Managers

    refs/heads/stable/*
      label code review (exclusive):
        -2/+2 opestack-stable-maint
        -1/+1 registered users
      label approved (exclusive): 0/+1: opestack-stable-maint

    refs/meta/*
      push: project bootstrappers

    refs/meta/config
      read: project bootstrappers
      read: project owners

  API Projects (metaproject):
    refs/*
      owner: Administrators

    refs/heads/*
      label code review -2/+2: openstack-doc-core
      label approved 0/+1: openstack-doc-core

  project foo:
    refs/*
      owner: Administrators
      create reference: foo-milestone  [client library only]
      push annotated tag: foo-milestone  [client library only]

    refs/heads/*
      label code review -2/+2: foo-core
      label approved 0/+1: foo-core

    refs/heads/milestone-proposed
      label code review -2/+2: foo-milestone
      label approved 0/+1: foo-milestone

Manual Administrative Tasks
===========================

The following sections describe tasks that individuals with root
access may need to perform on rare occations.


Renaming a Project
------------------

Renaming a project is not automated and is disruptive to developers,
so it should be avoided. Allow for an hour of downtime for the
project in question, and about 10 minutes of downtime for all of
Gerrit. All Gerrit changes, merged and open, will carry over, so
in-progress changes do not need to be merged before the move.

To rename a project:

#. Prepare a change to the Puppet configuration which updates
   projects.yaml/ACLs and jenkins-job-builder for the new name.

#. Stop puppet on review.openstack.org to prevent your interim
   configuration changes from being reset by the project management
   routines::

     sudo puppetd --disable

#. Gracefully stop Zuul on zuul.openstack.org::

     sudo kill -USR1 $(cat /var/run/zuul/zuul.pid)
     rm -f /var/run/zuul/zuul.pid /var/run/zuul/zuul.lock

#. Stop Gerrit on review.openstack.org::

     sudo invoke-rc.d gerrit stop

#. Update the database on review.openstack.org::

     sudo mysql --defaults-file=/etc/mysql/debian.cnf reviewdb

     update account_project_watches
     set project_name = "openstack/NEW"
     where project_name = "openstack/OLD";

     update changes
     set dest_project_name = "openstack/NEW", created_on = created_on
     where dest_project_name = "openstack/OLD";

#. Move both the git repository and the mirror on
   review.openstack.org::
   
     sudo mv ~gerrit2/review_site/git/openstack/{OLD,NEW}.git
     sudo mv /var/lib/git/openstack/{OLD,NEW}.git

#. Move the git repository on git.openstack.org::

     sudo mv /var/lib/git/openstack/{OLD,NEW}.git

#. Start Gerrit on review.openstack.org::

     sudo invoke-rc.d gerrit start

#. Start Zuul on zuul.openstack.org::

     sudo invoke-rc.d zuul start

#. Merge the prepared Puppet configuration change, removing the
   original Jenkins jobs via the Jenkins WebUI later if needed.

#. Start puppet again on review.openstack.org::

     sudo puppetd --enable

#. Rename the project in GitHub or, if this is a move to a new org, let
   the project management run create it for you and then remove the
   original later (assuming you have sufficient permissions).

#. If this is an org move and the project name itself is not
   changing, gate jobs may fail due to outdated remote URLs. Clear
   the workspaces on persistent Jenkins slaves to mitigate this::

     ssh -t $h.slave.openstack.org 'sudo rm -rf ~jenkins/workspace/*PROJECT*'

#. Again, if this is an org move rather than a rename and the GitHub
   project has been created but is empty, trigger replication to
   populate it::

     ssh -p 29418 review.openstack.org gerrit replicate --all

#. Submit a change that updates .gitreview with the new location of the
   project.

Developers will either need to re-clone a new copy of the repository,
or manually update their remotes with something like::

  git remote set-url origin https://git.openstack.org/$ORG/$PROJECT


Resetting a Username in Gerrit
------------------------------

Initially if a Gerrit username (which is used to associate SSH
connections to an account) has not yet been set, the user can type
it into the Gerrit WebUI... but there is no supported way for the
user to alter or correct it once entered. Further, if a defunct
account has the desired username, a different one will have to be
entered.

Because of this, often due to the user ending up with `Duplicate
Accounts in Gerrit`_, it may be requested to change the SSH username
of an account. Confirm the account_id number for the account in
question and remove the existing username external_id for that (it
may also be necessary to remove any lingering external_id with the
desired username if confirmed there is a defunct account associated
with it):

.. code-block:: mysql

  delete from account_external_ids where account_id=NNNN and external_id like 'username:%';

After this, the user should be able to re-add their username through
the Gerrit WebUI.


Duplicate Accounts in Gerrit
----------------------------

From time to time, outside events affecting SSO authentication or
identity changes can result in multiple Gerrit accounts for the same
user. This frequently causes duplication of preferred E-mail
addresses, which also renders the accounts unselectable in some
parts of the WebUI (notably when trying to add reviewers to a change
or members in a group). Gerrit does not provide a supported
mechanism for `Combining Gerrit Accounts`_, and doing so manually is
both time-consuming and error prone. As a result, the OpenStack
infrastructure team does not combine duplicate accounts for users
but can clean up these E-mail address issues upon request. To find
the offending duplicates:

.. code-block:: mysql

  select account_id from accounts where preferred_email='user@example.com';

Find out from the user which account_id is the one they're currently
using, and then null out the others with:

.. code-block:: mysql

  update accounts set preferred_email=NULL, registered_on=registered_on where account_id=OLD;


Combining Gerrit Accounts
-------------------------

While not supported by Gerrit, a fairly thorough account merge is
documented here (mostly as a demonstration of its unfortunate
complexity). Please note that the OpenStack infrastructure team does
not combine duplicate accounts for users upon request, but this
would be the process to follow if it becomes necessary under some
extraordinary circumstance.

Collect as much information as possible about all affected accounts,
and then go poking around in the tables listed below for additional
ones to determine the account_id number for the current account and
any former accounts which should be merged into it. Then for each
old account_id, perform these update and delete queries:

.. code-block:: mysql

  delete from account_agreements where account_id=OLD;
  delete from account_diff_preferences where id=OLD;
  delete from account_external_ids where account_id=OLD;
  delete from account_group_members where account_id=OLD;
  delete from account_group_members_audit where account_id=OLD;
  delete from account_project_watches where account_id=OLD;
  delete from account_ssh_keys where account_id=OLD;
  delete from accounts where account_id=OLD;
  update account_patch_reviews set account_id=NEW where account_id=OLD;
  update starred_changes set account_id=NEW where account_id=OLD;
  update change_messages set author_id=NEW, written_on=written_on where author_id=OLD;
  update changes set owner_account_id=NEW, created_on=created_on where owner_account_id=OLD;
  update patch_comments set author_id=NEW, written_on=written_on where author_id=OLD;
  update patch_sets set uploader_account_id=NEW, created_on=created_on where uploader_account_id=OLD;
  update patch_set_approvals set account_id=NEW, granted=granted where account_id=OLD;

If that last update query results in a collision with an error
like::

  ERROR 1062 (23000): Duplicate entry 'XXX-YY-NEW' for key 'PRIMARY'

Then you can manually delete the old approval:

.. code-block:: mysql

  delete from patch_set_approvals where account_id=OLD and change_id=XXX and patch_set_id=YY;

And repeat until the update query runs to completion.

After all the described deletes and updates have been applied, flush
Gerrit's caches so things like authentication will be rechecked
against the current DB contents:

.. code-block:: bash

  ssh review.openstack.org -p29418 gerrit flush-caches --all

Make the user aware that these steps have also removed any group
memberships, preferences, SSH keys, contact information, CLA
signatures, and so on associated with the old account so some of
these may still need to be added to the new one via the Gerrit WebUI
if they haven't been already. With a careful inspection of all
accounts involved it is possible to merge some information from the
old accounts into new ones by performing update queries similar to
the deletes above, but since this varies on a case-by-case basis
it's left as an exercise for the reader.


Deleting a User from Gerrit
---------------------------

This isn't normally necessary, but if you find that you need to
completely delete an account from Gerrit, perform the same delete
queries mentioned in `Combining Gerrit Accounts`_ and replace the
update queries for account_patch_reviews and starred_changes with:

.. code-block:: mysql

  delete from account_patch_reviews where account_id=OLD;
  delete from starred_changes where account_id=OLD;

The other update queries can be ignored, since deleting them in many
cases would result in loss of legitimate review history.