gerrit/Documentation/intro-user.txt

= User Guide

This is a Gerrit guide that is dedicated to Gerrit end-users. It
explains the standard Gerrit workflows and how a user can adapt Gerrit
to personal preferences.

It is expected that readers know about link:http://git-scm.com/[Git]
and that they are familiar with basic git commands and workflows.

[[gerrit]]
== What is Gerrit?

Gerrit is a Git server that provides link:access-control.html[access
control] for the hosted Git repositories and a web front-end for doing
link:#code-review[code review]. Code review is a core functionality of
Gerrit, but still it is optional and teams can decide to
link:#no-code-review[work without code review].

[[tools]]
== Tools

Gerrit speaks the git protocol. This means in order to work with Gerrit
you do *not* need to install any Gerrit client, but having a regular
git client, such as the link:http://git-scm.com/[git command line] or
link:http://eclipse.org/egit/[EGit] in Eclipse, is sufficient.

Still there are some client-side tools for Gerrit, which can be used
optionally:

* link:http://eclipse.org/mylyn/[Mylyn Gerrit Connector]: Gerrit
  integration with Mylyn
* link:https://play.google.com/store/apps/details?id=com.jbirdvegas.mgerrit[
  mGerrit]: Android client for Gerrit
* link:https://github.com/stackforge/gertty[Gertty]: Console-based
  interface for Gerrit

[[clone]]
== Clone Gerrit Project

Cloning a Gerrit project is done the same way as cloning any other git
repository by using the `git clone` command.

.Clone Gerrit Project
----
  $ git clone ssh://gerrithost:29418/RecipeBook.git RecipeBook
  Cloning into RecipeBook...
----

The URL for cloning the project can be found in the Gerrit web UI
under `Projects` > `List` > <project-name> > `General`.

For git operations Gerrit supports the link:user-upload.html#ssh[SSH]
and the link:user-upload.html#http[HTTP/HTTPS] protocols.

[NOTE]
To use SSH you must link:user-upload.html#configure_ssh[generate an SSH
key pair and upload the public SSH key to Gerrit].

[[code-review]]
== Code Review Workflow

With Gerrit _Code Review_ means to link:#review-change[review] every
commit *before* it is accepted into the code base. The author of a code
modification link:user-upload.html#push_create[uploads a commit] as a
change to Gerrit. In Gerrit each change is stored in a
link:#change-ref[staging area] where it can be checked and reviewed.
Only when it is approved and submitted it gets applied to the code
base. If there is feedback on a change, the author can improve the code
modification by link:#upload-patch-set[amending the commit and
uploading the new commit as a new patch set]. This way a change is
improved iteratively and it is applied to the code base only when is
ready.

[[upload-change]]
== Upload a Change

Uploading a change to Gerrit is done by pushing a commit to Gerrit. The
commit must be pushed to a ref in the `refs/for/` namespace which
defines the target branch: `refs/for/<target-branch>`.
The magic `refs/for/` prefix allows Gerrit to differentiate commits
that are pushed for review from commits that are pushed directly into
the repository, bypassing code review. For the target branch it is
sufficient to specify the short name, e.g. `master`, but you can also
specify the fully qualified branch name, e.g. `refs/heads/master`.

.Push for Code Review
----
  $ git commit
  $ git push origin HEAD:refs/for/master

  // this is the same as:
  $ git commit
  $ git push origin HEAD:refs/for/refs/heads/master
----

.Push with bypassing Code Review
----
  $ git commit
  $ git push origin HEAD:master

  // this is the same as:
  $ git commit
  $ git push origin HEAD:refs/heads/master
----

[[push-fails]]
[NOTE]
If pushing to Gerrit fails consult the Gerrit documentation that
explains the link:error-messages.html[error messages].

[[change-ref]]
When a commit is pushed for review, Gerrit stores it in a staging area
which is a branch in the special `refs/changes/` namespace. A change
ref has the format `refs/changes/XX/YYYY/ZZ` where `YYYY` is the
numeric change number, `ZZ` is the patch set number and `XX` is the
last two digits of the numeric change number, e.g.
`refs/changes/20/884120/1`. Understanding the format of this ref is not
required for working with Gerrit.

[[fetch-change]]
Using the change ref git clients can fetch the corresponding commit,
e.g. for local verification.

.Fetch Change
----
  $ git fetch https://gerrithost/myProject refs/changes/74/67374/2 && git checkout FETCH_HEAD
----

[NOTE]
The fetch command can be copied from the
link:user-review-ui.html#download[download commands] in the change
screen.

The `refs/for/` prefix is used to map the Gerrit concept of
"Pushing for Review" to the git protocol. For the git client it looks
like every push goes to the same branch, e.g. `refs/for/master` but in
fact for each commit that is pushed to this ref Gerrit creates a new
branch under the `refs/changes/` namespace. In addition Gerrit creates
an open change.

[[change]]
A change consists of a link:user-changeid.html[Change-Id], meta data
(owner, project, target branch etc.), one or more patch sets, comments
and votes. A patch set is a git commit. Each patch set in a change
represents a new version of the change and replaces the previous patch
set. Only the latest patch set is relevant. This means all failed
iterations of a change will never be applied to the target branch, but
only the last patch set that is approved is integrated.

[[change-id]]
The Change-Id is important for Gerrit to know whether a commit that is
pushed for code review should create a new change or whether it should
create a new patch set for an existing change.

The Change-Id is a SHA-1 that is prefixed with an uppercase `I`. It is
specified as footer in the commit message (last paragraph):

----
  Improve foo widget by attaching a bar.

  We want a bar, because it improves the foo by providing more
  wizbangery to the dowhatimeanery.

  Bug: #42
  Change-Id: Ic8aaa0728a43936cd4c6e1ed590e01ba8f0fbf5b
  Signed-off-by: A. U. Thor <author@example.com>
----

If a commit that has a Change-Id in its commit message is pushed for
review, Gerrit checks if a change with this Change-Id already exists
for this project and target branch, and if yes, Gerrit creates a new
patch set for this change. If not, a new change with the given
Change-Id is created.

If a commit without Change-Id is pushed for review, Gerrit creates a
new change and generates a Change-Id for it. Since in this case the
Change-Id is not included in the commit message, it must be manually
inserted when a new patch set should be uploaded. Most projects already
link:project-configuration.html#require-change-id[require a Change-Id]
when pushing the very first patch set. This reduces the risk of
accidentally creating a new change instead of uploading a new patch
set. Any push without Change-Id then fails with
link:error-missing-changeid.html[missing Change-Id in commit message
footer]. New patch sets can always be uploaded to a specific change
(even without any Change-Id) by pushing to the change ref, e.g.
`refs/changes/74/67374`.

Amending and rebasing a commit preserves the Change-Id so that the new
commit automatically becomes a new patch set of the existing change,
when it is pushed for review.

.Push new Patch Set
----
  $ git commit --amend
  $ git push origin HEAD:refs/for/master
----

Change-Ids are unique for a branch of a project. E.g. commits that fix
the same issue in different branches should have the same Change-Id,
which happens automatically if a commit is cherry-picked to another
branch. This way you can link:user-search.html[search] by the Change-Id
in the Gerrit web UI to find a fix in all branches.

Change-Ids can be created automatically by installing the `commit-msg`
hook as described in the link:user-changeid.html#creation[Change-Id
documentation].

Instead of manually installing the `commit-msg` hook for each git
repository, you can copy it into the
link:http://git-scm.com/docs/git-init#_template_directory[git template
directory]. Then it is automatically copied to every newly cloned
repository.

[[review-change]]
== Review Change

After link:#upload-change[uploading a change for review] reviewers can
inspect it via the Gerrit web UI. Reviewers can see the code delta and
link:user-review-ui.html#inline-comments[comment directly in the code]
on code blocks or lines. They can also link:user-review-ui.html#reply[
post summary comments and vote on review labels]. The
link:user-review-ui.html[documentation of the review UI] explains the
screens and controls for doing code reviews.

There are several options to control how patch diffs should be
rendered. Users can configure their preferences in the
link:user-review-ui.html#diff-preferences[diff preferences].

[[upload-patch-set]]
== Upload a new Patch Set

If there is feedback from code review and a change should be improved a
new patch set with the reworked code should be uploaded.

This is done by amending the commit of the last patch set. If needed
this commit can be fetched from Gerrit by using the fetch command from
the link:user-review-ui.html#download[download commands] in the change
screen.

It is important that the commit message contains the
link:user-changeid.html[Change-Id] of the change that should be updated
as a footer (last paragraph). Normally the commit message already
contains the correct Change-Id and the Change-Id is preserved when the
commit is amended.

.Push Patch Set
----
  // fetch and checkout the change
  // (checkout command copied from change screen)
  $ git fetch https://gerrithost/myProject refs/changes/74/67374/2 && git checkout FETCH_HEAD

  // rework the change
  $ git add <path-of-reworked-file>
  ...

  // amend commit
  $ git commit --amend

  // push patch set
  $ git push origin HEAD:refs/for/master
----

[NOTE]
Never amend a commit that is already part of a central branch.

Pushing a new patch set triggers email notification to the reviewers.

[[multiple-features]]
== Developing multiple Features in parallel

Code review takes time, which can be used by the change author to
implement other features. Each feature should be implemented in its own
local feature branch that is based on the current HEAD of the target
branch. This way there is no dependency to open changes and new
features can be reviewed and applied independently. If wanted, it is
also possible to base a new feature on an open change. This will create
a dependency between the changes in Gerrit and each change can only be
applied if all its predecessor are applied as well. Dependencies
between changes can be seen from the
link:user-review-ui.html#related-changes-tab[Related Changes] tab on
the change screen.

[[watch]]
== Watching Projects

To get to know about new changes you can link:user-notify.html#user[
watch the projects] that you are interested in. For watched projects
Gerrit sends you email notifications when a change is uploaded or
modified. You can decide on which events you want to be notified and
you can filter the notifications by using link:user-search.html[change
search expressions]. For example '+branch:master file:^.*\.txt$+' would
send you email notifications only for changes in the master branch that
touch a 'txt' file.

It is common that the members of a project team watch their own
projects and then pick the changes that are interesting to them for
review.

Project owners may also configure
link:intro-project-owner.html#notifications[notifications on
project-level].

[[adding-reviewers]]
== Adding Reviewers

In the link:user-review-ui.html#reviewers[change screen] reviewers can
be added explicitly to a change. The added reviewer will then be
notified by email about the review request.

Mainly this functionality is used to request the review of specific
person who is known to be an expert in the modified code or who is a
stakeholder of the implemented feature. Normally it is not needed to
explicitly add reviewers on every change, but you rather rely on the
project team to watch their project and to process the incoming changes
by importance, interest, time etc.

There are also link:intro-project-owner.html#reviewers[plugins which
can add reviewers automatically] (e.g. by configuration or based on git
blame annotations). If this functionality is required it should be
discussed with the project owners and the Gerrit administrators.

[[dashboards]]
== Dashboards

Gerrit supports a wide range of link:user-search.html#search-operators[
query operators] to search for changes by different criteria, e.g. by
status, change owner, votes etc.

The page that shows the results of a change query has the change query
contained in its URL. This means you can bookmark this URL in your
browser to save the change query. This way it can be easily re-executed
later.

Several change queries can be also combined into a dashboard. A
dashboard is a screen in Gerrit that presents the results of several
change queries in different sections, each section having a descriptive
title.

A default dashboard is available under `My` > `Changes`. It has
sections to list outgoing reviews, incoming reviews and recently closed
changes.

Users can also define link:user-dashboards.html#custom-dashboards[
custom dashboards]. Dashboards can be bookmarked in a browser so that
they can be re-executed later.

It is also possible to link:#my-menu[customize the My menu] and add
menu entries for custom queries or dashboards to it.

Dashboards are very useful to define own views on changes, e.g. you can
have different dashboards for own contributions, for doing reviews or
for different sets of projects.

[NOTE]
You can use the link:user-search.html#limit[limit] and
link:user-search.html#age[age] query operators to limit the result set
in a dashboard section. Clicking on the section title executes the
change query without the `limit` and `age` operator so that you can
inspect the full result set.

Project owners can also define shared
link:user-dashboards.html#project-dashboards[dashboards on
project-level]. The project dashboards can be seen in the web UI under
`Projects` > `List` > <project-name> > `Dashboards`.

[[submit]]
== Submit a Change

Submitting a change means that the code modifications of the current
patch set are applied to the target branch. Submit requires the
link:access-control.html#category_submit[Submit] access right and is
done on the change screen by clicking on the
link:user-review-ui.html#submit[Submit] button.

In order to be submittable changes must first be approved by
link:user-review-ui.html#vote[voting on the review labels]. By default
a change can only be submitted if it has a vote with the highest value
on each review label and no vote with the lowest value (veto vote).
Projects can configure link:intro-project-owner.html#labels[custom
labels] and link:intro-project-owner.html#submit-rules[custom submit
rules] to control when a change becomes submittable.

How the code modification is applied to the target branch when a change
is submitted is controlled by the
link:project-configuration.html#submit_type[submit type] which can be
link:intro-project-owner.html#submit-type[configured on project-level].

Submitting a change may fail with conflicts. In this case you need to
link:#rebase[rebase] the change locally, resolve the conflicts and
upload the commit with the conflict resolution as new patch set.

If a change cannot be merged due to path conflicts this is highlighted
on the change screen by a bold red `Cannot Merge` label.

[[rebase]]
== Rebase a Change

While a change is in review the HEAD of the target branch can evolve.
In this case the change can be rebased onto the new HEAD of the target
branch. When there are no conflicts the rebase can be done directly
from the link:user-review-ui.html#rebase[change screen], otherwise it
must be done locally.

.Rebase a Change locally
----
  // update the remote tracking branches
  $ git fetch

  // fetch and checkout the change
  // (checkout command copied from change screen)
  $ git fetch https://gerrithost/myProject refs/changes/74/67374/2 && git checkout FETCH_HEAD

  // do the rebase
  $ git rebase origin/master

  // resolve conflicts if needed and stage the conflict resolution
  ...
  $ git add <path-of-file-with-conflicts-resolved>

  // continue the rebase
  $ git rebase --continue

  // push the commit with the conflict resolution as new patch set
  $ git push origin HEAD:refs/for/master
----

Doing a manual rebase is only necessary when there are conflicts that
cannot be resolved by Gerrit. If manual conflict resolution is needed
also depends on the link:intro-project-owner.html#submit-type[submit
type] that is configured for the project.

Generally changes shouldn't be rebased without reason as it
increases the number of patch sets and creates noise with
notifications. However if a change is in review for a long time it may
make sense to rebase it from time to time, so that reviewers can see
the delta against the current HEAD of the target branch. It also shows
that there is still an interest in this change.

[NOTE]
Never rebase commits that are already part of a central branch.

[[abandon]]
[[restore]]
== Abandon/Restore a Change

Sometimes during code review a change is found to be bad and it should
be given up. In this case the change can be
link:user-review-ui.html#abandon[abandoned] so that it doesn't appear
in list of open changes anymore.

Abandoned changes can be link:user-review-ui.html#restore[restored] if
later they are needed again.

[[topics]]
== Using Topics

Changes can be grouped by topics. This is useful because it allows you
to easily find related changes by using the
link:user-search.html#topic[topic search operator]. Also on the change
screen link:user-review-ui.html#same-topic[changes with the same topic]
are displayed so that you can easily navigate between them.

Often changes that together implement a feature or a user story are
group by a topic.

Assigning a topic to a change can be done in the
link:user-review-ui.html#project-branch-topic[change screen].

It is also possible to link:user-upload.html#topic[set a topic on
push].

.Set Topic on Push
----
  $ git push origin HEAD:refs/for/master%topic=multi-master
----

[[drafts]]
== Working with Drafts

Changes can be uploaded as drafts. By default draft changes are only
visible to the change owner. This gives you the possibility to have
some staging before making your changes visible to the reviewers. Draft
changes can also be used to backup unfinished changes.

A draft change is created by pushing to the magic
`refs/drafts/<target-branch>` ref.

.Push a Draft Change
----
  $ git commit
  $ git push origin HEAD:refs/drafts/master
----

Draft changes have the state link:user-review-ui.html#draft[Draft] and
can be link:user-review-ui.html#publish[published] or
link:user-review-ui.html#delete[deleted] from the change screen.

By link:user-review-ui.html#reviewers[adding reviewers] to a draft
change the change is made visible to these users. This way you can
collaborate with other users in privacy.

By pushing to `refs/drafts/<target-branch>` you can also upload draft
patch sets to non-draft changes. Draft patch sets are immediately
visible to all reviewers of the change, but other users cannot see the
draft patch set. A draft patch set can be published and deleted in the
same way as a draft change.

[[inline-edit]]
== Inline Edit

It is possible to link:user-inline-edit.html#editing-change[edit
changes inline] directly in the web UI. This is useful to make small
corrections immediately and publish them as a new patch set.

It is also possible to link:user-inline-edit.html#create-change[create
new changes inline].

[[project-administration]]
== Project Administration

Every project has a link:intro-project-owner.html#project-owner[project
owner] that administrates the project. Project administration includes
the configuration of the project
link:intro-project-owner.html#access-rights[access rights], but project
owners have many more possibilities to customize the workflows for a
project which are described in the link:intro-project-owner.html[
project owner guide].

[[no-code-review]]
== Working without Code Review

Doing code reviews with Gerrit is optional and you can use Gerrit
without code review as a pure Git server.

.Push with bypassing Code Review
----
  $ git commit
  $ git push origin HEAD:master

  // this is the same as:
  $ git commit
  $ git push origin HEAD:refs/heads/master
----

[NOTE]
Bypassing code review must be enabled in the project access rights. The
project owner must allow it by assigning the
link:access-control.html#category_push_direct[Push] access right on the
target branch (`refs/heads/<branch-name>`).

[NOTE]
If you bypass code review you always need to merge/rebase manually if
the tip of the destination branch has moved. Please keep this in mind
if you choose to not work with code review because you think it's
easier to avoid the additional complexity of the review workflow; it
might actually not be easier.

[NOTE]
The project owner may enable link:user-upload.html#auto_merge[
auto-merge on push] to benefit from the automatic merge/rebase on
server side while pushing directly into the repository.

[[preferences]]
== Preferences

There are several options to control the rendering in the Gerrit web UI.
Users can configure their preferences under `Settings` > `Preferences`.

The following preferences can be configured:

- [[show-site-header]]`Show Site Header`:
+
Whether the site header should be shown.

- [[use-flash]]`Use Flash Clipboard Widget`:
+
Whether the Flash clipboard widget should be used. If enabled Gerrit
offers a copy-to-clipboard icon next to IDs and commands that need to
be copied frequently, such as the Change-Ids, commit IDs and download
commands.

- [[cc-me]]`CC Me On Comments I Write`:
+
Whether you get notified by email as CC on comments that you write
yourself.

- [[review-category]]`Display In Review Category`:
+
This setting controls how the values of the review labels in change
lists and dashboards are visualized.
+
** `None`:
+
For each review label only the voting value is shown. Approvals are
rendered as a green check mark icon, vetos as a red X icon.
+
** `Show Name`:
+
For each review label the voting value is shown together with the full
name of the voting user.
+
** `Show Email`:
+
For each review label the voting value is shown together with the email
address of the voting user.
+
** `Show Username`:
+
For each review label the voting value is shown together with the
username of the voting user.
+
** `Show Abbreviated Name`:
+
For each review label the voting value is shown together with the
initials of the full name of the voting user.

- [[page-size]]`Maximum Page Size`:
+
The maximum number of entries that are shown on one page, e.g. used
when paging through changes, projects, branches or groups.

- [[date-time-format]]`Date/Time Format`:
+
The format that should be used to render dates and timestamps.

- [[relative-dates]]`Show Relative Dates In Changes Table`:
+
Whether timestamps in change lists and dashboards should be shown as
relative timestamps, e.g. '12 days ago' instead of absolute timestamps
such as 'Apr 15'.

- [[change-size-bars]]`Show Change Sizes As Colored Bars`:
+
Whether change sizes should be visualized as colored bars. If disabled
the numbers of added and deleted lines are shown as text, e.g.
'+297, -63'.

- [[show-change-number]]`Show Change Number In Changes Table`:
+
Whether in change lists and dashboards an `ID` column with the numeric
change IDs should be shown.

- [[mute-common-path-prefixes]]`Mute Common Path Prefixes In File List`:
+
Whether common path prefixes in the file list on the change screen
should be link:user-review-ui.html#repeating-path-segments[grayed out].

- [[diff-view]]`Diff View`:
+
Whether the Side-by-Side diff view or the Unified diff view should be
shown when clicking on a file path in the change screen.

[[my-menu]]
In addition it is possible to customize the menu entries of the `My`
menu. This can be used to make the navigation to frequently used
screens, e.g. configured link:#dashboards[dashboards], quick.


GERRIT
------
Part of link:index.html[Gerrit Code Review]

SEARCHBOX
---------