Difference between revisions of "Infrastructure/Phabricator"

(→‎Installing Arcanist: add a link to the generic instructions for the other operating systems)
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Before editing anything, create a new branch for your patch:
Before editing anything, create a new branch for your patch:
$ git checkout -t -b <branchname> # the -t flag makes git "track" the current branch
$ arc feature  <branchname>
(For Git experts: this is equivalent to `git checkout -t -b <branchname>`)
Now make changes on the feature branch. When you're ready to have your changes reviewed, enter the following command:
Now make changes on the feature branch. When you're ready to have your changes reviewed, enter the following command:

Revision as of 15:48, 7 October 2018

Phabricator is KDE's task management and patch review system. This page is intended to serve as a general-purpose introduction to the most important aspects: submitting and reviewing patches. It should not take long before you are happily using Phabricator.

The KDE community does not use the Phabricator bug reporting function. We continue to use bugzilla at https://bugs.kde.org

Basic Tasks

Logging in

Log in to Phabricator with your KDE Identity account. If you don't have one, you can sign up for one here. At the Phabricator home page, click the "Log in" button on the top of the page and enter your KDE Identity username and password:

Phabricator login 2.png If your KDE Identity account works on http://identity.kde.org, but not on http://phabricator.kde.org, please contact the KDE sysadmins at [email protected]

Getting help

The official documentation is in the Phabricator book and on their website -- note that since everything is under rapid development, most of the documentation is incomplete. A good way to find the information you're looking for is to search Phabricator upstream.

Posting a Patch using the website

Once you have set up your development environment and created a patch, you can submit it using Phabricator!

Log in to Phabricator and click on Code Review in the list on the left. Then click the +Create Diff button in the upper-right corner of the screen. Paste the text of the diff or upload the file using the file dialog. Reviewers are mostly added automatically, but if your patch includes any visual or user interface changes, please add #vdg as a reviewer to make sure the KDE Visual Design Group sees it! Please make sure to add a screenshot, too.

Formatting your patch

The Title of your patch will become the git commit message, so please follow commit message best practices when titling the patch.

In the Summary section, write at least one sentence describing your change and why it is necessary, adding more detail if necessary.

Add special keywords

If your patch is intended to fix a Bugzilla ticket, include one of the following on its own line in the Summary section:

BUG: 385942


FEATURE: 384936

(Just the Bugzilla ticket number, not the full URL)

Use BUG: If the Bugzilla describes a bug, and FEATURE: if the Bugzilla ticket describes a feature request. Either of these tags will cause that Bugzilla ticket to be automatically closed when the patch is committed.

If you added the BUG: or FEATURE: tag, also add another tag indicating what version receives the fix or new feature:

FIXED-IN: [version]

Replace [version] with an appropriate version string; see Guidelines and HOWTOs/Write a version string to find out how to write one. If you can't figure it out, don't worry about it and just omit the tag; a KDE developer will help you add it during code review.

Here is more information about other special messages that interact with Bugzilla tickets. You can also add special messages that interact with other Phabricator tools (e.g. Maniphest tasks).

Include some screenshots

For patches that change something about the user interface, it's customary to include a screenshot of how the interface looks with your patch. Bonus points for including a "Before" image too, so reviewers can easily compare them.

What happens next?

After you've submitted your patch, KDE developers for the software in question will review it and provide feedback. Often this can take a few days. However if nobody has responded after a week, that it's likely that the review was overlooked (sorry about that!) and it's appropriate to a comment saying, "Ping!" or something to that effect.

Once the patch is accepted, KDE Developers will land it for you!

Using Arcanist to post patches

After you've posted a few patches, using the web UI to post patches gets tiresome. Arcanist is a tool to simplify and speed up the process of posting, updating, and merging Phabricator patches. Setting it up is easy:

Installing Arcanist

Debian/Ubuntu/KDE Neon

$ sudo apt install arcanist


$ sudo dnf copr enable kanarip/phabricator
$ sudo dnf install arcanist



$ sudo zypper ar -f https://download.opensuse.org/repositories/devel:tools:scm/openSUSE_Tumbleweed/devel:tools:scm.repo
$ sudo zypper install arcanist

Leap 15:

$ sudo zypper ar -f https://download.opensuse.org/repositories/devel:tools:scm/openSUSE_Leap_15.0/devel:tools:scm.repo
$ sudo zypper install arcanist


$ yaourt -S arcanist-git


The default portage tree does not have an ebuild, so unless you already have it, you need to add an overlay, e.g. the kde one:

$ sudo layman -a kde

Once that is done, you can emerge it:

$ sudo emerge -av arcanist

You might have to install and maybe unmask a few php related packages, follow the instructions portage gives you.

Keep in mind that it is a vcs version (9999), so it doesn't have release updates and you are in charge of keeping it up to date.


Arcanist User Guide: Windows

The most non-obvious step is that you will need to configure your PHP installation to use Curl. This requires editing the php.ini configuration file to add the line extension_dir = "ext" and add php_curl to the list of extensions. After adding php.exe to your PATH and installing arcanist/libphutil, you can run arc by defining a function in your Powershell profile:

 function arc { php -f "C:\path\to\arcanist.php" -- $args }

After you have installed Arc, you can learn more using man arc or arc --help. Another command useful for getting a feel for Phabricator's style is arc anoid.

Other operating systems

Follow the the instruction of the Arcanist Quick Start guide.

Perform one-time setup steps

Before you are able to use arc for work you will need to install a certificate that will allow it to login to Phabricator:

$ arc install-certificate https://phabricator.kde.org

Just follow the instructions it provides: you will have to visit the page it indicates and copy the API token you find on that page back to the shell.

Next, you will need to tell git who you really are, so your patches will include correct authorship information and can be attributed to yourself. This also only needs to be done once:

$ git config --global user.name "<Your real name>"
$ git config --global user.email "<Your identity.kde.org email address>"

Both of these steps only need to be done once.


The sanest and easiest way to use arc is to follow a typical feature branch workflow: keep your master branch synchronized with the upstream repository, and make all changes on separate branches. Each patch needs its own private, temporary branch. Once your patch has been merged, delete the feature branch, and make another new branch for the next patch.

Step 1: Create a new diff

Before editing anything, create a new branch for your patch:

$ arc feature  <branchname>
(For Git experts: this is equivalent to `git checkout -t -b <branchname>`)

Now make changes on the feature branch. When you're ready to have your changes reviewed, enter the following command:

$ arc diff     # this will do the `git add` and `git commit` for you; if it asks about ignoring untracked files, enter 'y'

When you run arc diff, you will go through a series of dialogues. At the end, you will be asked to rewrite your Git commit message to fit the standard Differential format, like so:

<first line of original git commit message>

Summary: <rest of original commit message>

Test Plan:



<first line of original git commit message> will become the commit message, so please follow commit message best practices.

As when using the web UI, enter any special Bugzilla keywords (such as BUG: 385942) on their own lines in the "Summary" section.

As when using the web UI, there is no need to specifically add anyone under the "Reviewers" or "Subscribers" sections unless your patch includes any visual or user interface changes. In this case, please add #vdg as a reviewer to make sure the KDE Visual Design Group sees it!

Step 2: Update your diff in response to review comments

After arc uploads the patch to phabricator, the project's reviewers will take a look and give you some comments. If you get a thumbs up immediately, you can skip this step. But often you will get a review like "looks good, we can take it if you fix problems x, y, and z." Make the necessary changes, add an extra commit to the git branch, and update the Phabricator revision:

[implement changes based on review comments]
$ arc diff

Step 3: Land your diff

If you do not have a KDE Developer Account, then someone who does will have to land your patch for you. Otherwise, you can do it yourself once the patch has been accepted and reviewers have given you permission to "ship it!"

First make sure that the world is sane, and that only your patch will be landed:

$ [make sure you are on your feature branch]
$ arc land --preview

The output of that command should show only the commit message for your patch. If you see more than that, stop and ask your reviewers for help.

Landing on master

This is simple:

$ arc land

Landing on the "Stable branch"

By default, arc will land the patch onto whatever branch was the parent. For example, if you branched from master, arc will land on master; if you branched from Applications/18.04, arc will land on that branch instead.

Sometimes you will be asked to land your diff on the "stable branch", even though you originally branched from master. To make this work, rebase your patch on the stable branch. Here is an example of how to rebase a patch from master onto the Applications/18.04 stable branch:

$ [make sure you are on your feature branch]
$ git fetch
$ git rebase --onto origin/Applications/18.04 master
$ arc land --onto Applications/18.04

Note that in most repositories, after committing to the "stable" branch you are expected to merge the "stable" branch to "master" afterwards (check the Git history to be sure):

$ git checkout master
$ git merge -Xours origin/Applications/18.04
$ git push

Landing someone else's diff

If you have a contributor account and you are helping someone without one through the process, you will need to land their diff for them once it's been accepted. Here's how:

$ arc patch <revision ID>
$ git show HEAD

At this point, you need to verify that the authorship information shown is correct. If it's not, you will need to ask the patch author for their real name and email address. Then you use that information to update the local commit for the patch like so:

# Make sure you're on the branch that corresponds to the patch!
$ git commit --amend --author="firstname lastname <email address>"

At this point, you can land the diff normally, as described above.

Arcanist Tips & Tricks

Look before you diff

You can check with arc which what Arcanist will do before performing the actual upload with arc diff if you are unsure what will happen. In particular, look for which commits will be included in your Diff.

arc diff: specify a revision manually

Sometimes - if you messed up with your git branches - arc cannot properly determine which revision (D12345) should be updated. In this case you can use arc diff --update D12345. See arc help diff.

Updating the summary of the Differential from the local Git commit message

If you changed the commit message locally and want to update the text in the summary in Differential, call Arc like this:

$ arc diff --edit --verbatim

Updating the local Git commit message from changes done on Phabricator

If you or someone else updated the title, summary, test plan, reviewers or subscribers of a Diff using the web editor in Phabricator, Arcanist allows to sync those changes back to your local Git commit message:

$ arc amend

Note that in general Arcanist will do this automatically for you once you arc land.

Advanced Tasks

Once in a while a reviewer will tell you to do specific things. This section will help you to figure out what is meant to be done.

"Please do that in a separate commit"

Should your patch contain an unrelated change, your reviewer will ask you to undo that part and possibly open a new Diff for that. Here is what you can do:

If the change in question is in a separate commit on your local branch:

$ git revert <unrelated change>
$ arc diff # this updates the first Diff
$ git checkout -b <new branch name> master
$ git cherry-pick <unrelated change>
$ arc diff # this creates a new Diff for the unrelated change

If you mixed different changes in a single commit on your local branch:

$ git reset HEAD^
$ git add -p # type "?" for help, then pick all hunks you want to keep
$ git stash # the stash now contains the hunks for the second patch
$ git commit
$ arc diff # this updates the first Diff
$ git checkout -b <new branch name> master
$ git stash pop
$ git commit
$ arc diff # this creates a new Diff for the unrelated change

In case this does not work for you, there's always the plain old copy-and-paste. In general, it is best to avoid adding unrelated changes from the beginning. :-)

Marking patches as dependent on other patches

Sometimes you will want to submit a patch that depends on another patch, creating a dependency chain.

If each patch is intended for a different project

Example: you submit a patch to add new feature in KIO, and then submit another patch for Dolphin that uses that feature. Here's what you do:

  1. Create your first patch as above
  2. When creating the second patch, add the following to its own line in the "Summary" section:
    Depends on DXXXX
    (Replace "DXXXX" with the ID of the dependent patch, not the full URL)

If the patches are all for the same project

Example: you are implementing multiple new features for a single project that each depend on the patch for the prior feature. Here's what you do:

  1. Create a branch to track the first feature:
    $ git checkout -b <branch name for feature 1> --track origin/master

    Then implement the feature and make a commit.

  2. Then create a branch for your second feature, tracking the first branch:
    git checkout -b <branch name for feature 2> --track <branch name for feature 1>

    As above, implement the feature and make a commit. Continue this pattern for any other required dependent features.

  3. When you're ready to turn your dependency chain feature branches into patches, do the following:
    $ git checkout <branch name for feature 1>
    $ arc diff [then go through the process of creating the patch normally]
    $ git checkout <branch name for feature 2>
    git commit --amend  [then add the special text "Depends on DXXXX", replacing DXXXX with the ID of the first patch
    $ arc diff [then go through the process of creating the patch normally]

    ...And so on.

  4. After you get comments, you will have to make changes to your patches and re-base dependent patches:
    $ git checkout <branch name for feature 1>
    [Make changes]
    $ git add -u
    $ git commit
    $ arc diff
    $ git checkout <branch name for feature 2>
    $ git rebase <branch name for feature 1>
    $ git add -u
    $ git commit
    $ arc diff

    ...And so on.

  5. When you're ready to land any or all of your patches, do it in sequence, starting from the patch with no unmet dependencies:
    $ git checkout <branch name for feature 1>
    $ arc land
    $ git checkout <branch name for feature 2>
    $ git rebase origin/<target branch>
    $ arc land

How to review someone else's patch

Arcanist (arc) makes it easy to review someone's patch (if you haven't already, see #Installing Arcanist). First, find the patch's revision ID. For example, for https://phabricator.kde.org/D11184, the ID is D11184.

Next, check out or enter the source repository for the patch. The repository is listed on the web UI: Konsole repository for patch.png

$ git clone git://anongit.kde.org/konsole.git
# If you've already checked out the repository, you don't need to clone it again, just cd do it

Now, apply the patch:

$ arc patch <revision ID>

Answer y to any questions that are posed. Arc will automatically create a branch named arcpatch-<revision ID> for the patch, so it won't damage your checkout at all.

Now it's time to compile and run the software to make sure that the patch does what it says it does and doesn't cause any regressions! If you haven't already set up a development environment, it's time to do so. See Get_Involved/development#Set_up_your_development_environment. Follow the instructions to compile and run the program.

Perform QA

It's important to thoroughly test patches to ensure that bad code and regressions don't slip in. This is the entire purpose of having a review infrastructure; it is very important.

First execute the Test Plan that the submitter wrote. Does it all still work for you? If not, return to the web UI and Request Changes, writing a detailed comment explaining what didn't work. It is permissible to do this even if you have not been specified as a reviewer!

If the original Test Plan succeeds, try to break the patch. Here are some ideas:

  1. Remove the program's configuration file (~/.config/<program name>rc ) and re-open it
  2. Try the program with a HiDPI scale factor (or without one) or with a different default font size
  3. If it's a new feature, feed it unexpected input
  4. Test related functionality

Try to break it! An acceptable patch will handle corner cases and variations in configuration. The price of configurability is vigilant testing! We owe it to our users to test using many configurations, not just the defaults or our personal settings.

Perform code review

Need a section on code review here, preferably written by a core KDE developer or another very experienced developer

Engage with the author and other reviewers

After you have run the program and evaluated the patch, it's time to leave some review comments on the webpage (https://phabricator.kde.org/<revision ID>). If you have been specified as a reviewer, or are a member of a group that has been specified as a reviewer, it is permissible to Accept the patch. But keep in mind that reviewing involves responsibility: you are giving a thumbs-up to code that will be run potentially by millions of people.


Creating custom dashboard feeds

You can customize your Phabricator homepage by creating a new dashboard. However, the selection of what you can post on your dashboard is limited. The defaults will show all tasks from all projects.

To narrow this down, you need to define a custom query to serve as a filter. For example, if you work on Plasma Mobile and want to monitor the to-do list, perhaps you want to show only tasks which are in the Plasma Mobile and are tagged as open. To do that, enter Maniphest, select "advanced search," select the appropriate terms, then click "save custom query." You can give your query a name. Once it is saved, the query will become available as a new filter for creating feeds on your dashboard. (In Differential you seem to need to perform the test search before the "save query" button becomes visible.)

This page was last edited on 7 October 2018, at 15:48. Content is available under Creative Commons License SA 4.0 unless otherwise noted.