Gerrit User Summit 2018

The Gerrit User Summit 2018 has ended. It has been a truly memorable event and with strong emotions, gratitude and celebration of the success of the Gerrit OpenSource project.

During the hackathon, some major events happened:

  • The release of Gerrit v2.16
  • Support for Kubernetes
  • New plugins contributed by Qualcomm
  • The announcement of a new maintainer, Marco Miller from Ericsson, congrats!

Hackathon and Gerrit v2.16

The hackathon took place at SAP (2 days) and Cloudera (1 day) in Palo Alto with the main focus of completing the migration to PolyGerrit and cut the v2.16 release. Three major milestones of the Gerrit project:

  1. PolyGerrit as default UI for Gerrit Code Review.
  2. Migration of the groups to NoteDb
  3. Support of the Git protocol v2

With regards to the achievement #1, during the hackathon, the commit for removing all the GWT related code from Gerrit master has been finally merged.

PolyGerrit as default Gerrit Code Review UI

The PolyGerrit Team has reached the summit of the long and troubled journey of getting rid of the outdated and Gerrit GWT UI. Kasper and Logan (Google) burned every single bit of their development energy to fix, implement and fill all the remaining gaps in the user journeys.

On Gerrit v2.16, PolyGerrit UI is the default and standard way of interacting with Gerrit Code Review. GWT is still there for allowing people to smoothly adapt to the new interface. However, the next forthcoming version of Gerrit v3.0 will not contain anymore any reference to the old UI. People will still have a few more months to adapt and, from the feedback received on GerritHub.io, they seem to not miss the GWT interface at all.

Well done to the entire PolyGerrit Team, starting from Andrew who kicked off the project back in 2015 to Wyatt, Becky, Victor, Kasper and Logan who brought it up to the usability and portability to multiple devices as it is today. Thanks to their amazing effort, we can all interact with Gerrit Code Review wherever and whenever we want, without losing speed and effectiveness.

Migration of Gerrit groups to NoteDb

One more step towards the complete elimination of ReviewDb has been achieved in Gerrit v2.16: there isn’t anymore any mutable data in the leftover of the (in)famous Gerrit DB. The new version includes a new git repository (All-Groups) which contains all the information related to the groups create through the Gerrit UI.

What’s left in ReviewDb? Not much: only the schema version. When you install Gerrit it is populated with a single row and a single column with the value ‘170’ and will never change. There is no need to share it across master or slaves: just set database.type = h2 and forget about it.

Git protocol v2

It is a major achievement of Gerrit v2.16 as the Git wire protocol v2 solves the performance problems of large repositories: the refs filtering during the advertisement phase.

In a nutshell, if you were fetching a single from a repository with 500k refs, the server would have sent a huge payload of all refs with the associated SHA1s even if at the end of the day you wanted only to fetch a single one. The delay could have been of several seconds if not minutes, which is quite relevant if you are fetching all the times, like in a CI/CD pipeline.

Git protocol v2 reduced the refs advertisement phase by over 70%, which makes Gerrit v2.16 so appealing that you may want to place in the top 5 tasks of your backlog.

Farewell to GWT UI code

Even though Gerrit v2.16 keeps the ability to display the old-fashioned GWT Gerrit UI, the code has been definitely removed on the Gerrit master branch, which will the base for Gerrit v3.0 that will be released in Spring 2019.

This is a memorable moment because represents the final act of making PolyGerrit UI the unified user-experience of Gerrit moving forward.

Data and Insights of the Hackathon

This year the event has been truly focused as well on the analytics side of the Code Review and the entire CI/CD pipeline: was it possibly the location, Cloudera, the world leader in OpenSource BigData and Analytics, giving the right vibrations? Possibly, yes.

Numbers

Over 20 people have attended the Hackathon on-site and, for the first time, remotely via video-conference, from companies and countries all around the world:

  1. Google (USA and Germany)
  2. CollabNet (Japan and Germany)
  3. GerritForge (UK, Ireland, Italy, and Germany)
  4. SAP (Germany)
  5. Qualcomm (USA)
  6. Ericsson (Canada)
  7. Wikimedia Foundation (UK)

Over 300+ changes have been uploaded and 244 of them have been already merged.

They have been working on 44 projects, showing how diverse is today the universe of Gerrit Code Review and its associated plugins and integrations.

Gerrit DevOps Analytics

GerritForge has been hacking on improving the platform that powers the Gerrit Code Review Analytics Platform which has been serving the community for many years.

For the first time, thanks to the introduction of branch-level analytics, the community had data automatically crunched in near-real time of what was happening on the master branch and on the on-going stable 2.16 release.

As a matter of fact, the numbers mentioned before are directly coming from Gerrit DevOps Analytics. Thanks again GerritForge for innovating and improving the Gerrit Code Review platform.

Gerrit Analytics Wizard

For the first time, two new contributors from GerritForge, Tony and Ponch, finalized and demoed a new plugin called ‘analytics-wizard’ that allows anyone with a Gerrit server to set up a mini-version of the Gerrit DevOps Analytics, using Docker, ElasticSearch, and Kibana.

Two new plugins: batch and tasks

Qualcomm has released two new plugins based on their experience of running complex pipelines on a multi-master Gerrit setup. The majority of the code was developed in-house before the hackathon. However, the final release and announced happened this week and I am sure it will allow many other companies to benefit from their experience of validating complex multi-repo changes on a large scale CI system.

Batch

This plugin provides a mechanism for building and previewing sets of proposed updates to multiple projects/refs that should be applied in a batch. These updates are built with Gerrit changes.

Task

The plugin provides a mechanism to manage tasks which need to be performed on changes along with a way to expose and query this information. Tasks are organized hierarchically, and task definitions use Gerrit queries to define which changes each task applies to, and how to define the status criteria for each task. An important use case of the task plugin is to have a common place for CI systems to define which changes they will operate on, and when they will do so.

Gerrit on Kubernetes from SAP and GerritForge

Luke (GerritForge), Matthias (SAP) and Thomas (SAP remotely from Germany) worked on a PoC for supporting Kubernetes deployments.

Last year SAP started using containerized slaves and decided to go cloud native and base our future Gerrit deployments on Kubernetes and leverage project Gardener to support multiple cloud providers. Matthias worked with Thomas to prepare a PoC and a demo the current work in progress and discuss plans moving forward.

The code has been published to the new k8s-gerrit repository and new commits will be subject to the standard Gerrit Code Review process.

Luke prepared an example of Gerrit v2.15 deployment in Kubernetes (single master at the moment) with shared storage and showed how to upgrade easily by leveraging Helm Charts deployments through Tiler.

Even though the two projects started in parallel, they agreed to cooperate and work together with the community to have a unified Kubernetes deployment code-base for installing and upgrading multi-master Gerrit setups. This is definitely an area where we will see very interesting developments very soon.

What about the Summit?

The talks of the summit have been very interesting this year and have covered mostly three main topics: Gerrit roadmap and scalability, sharing of real-life migrations to Gerrit v2.14 and v2.15 and, as previously mentioned, Data Analytics & Insights including research work on using machine-learning for supporting the Code Review process.

All the talks are getting published as we speak on each talk of the Gerrit User Summit Schedule.

All the talks have been recorded and will be published within the next few weeks on the GerritForge TV YouTube channel.

More blog posts will follow with more background on each talk, stay tuned and watch this space to know more about what has been presented and announced at the Summit.

Proposals for the next Gerrit User Summit 2019

The overall feedback on the summit has been very positive, including the Birthday Party organized and sponsored by GerritForge for the 10th anniversary of the Gerrit Code Review project.

During the final closing keynote, many interesting proposals have been made:

  • Gerrit users’ wish-list session.
    Any Gerrit user can feed the backlog of new feature proposing what they will like to see implemented
  • Gerrit plugin hackathon.
    Learn how to implement Gerrit plugin and trying to put together in one or two days something useful using any of the programming languages they wish, including Java, Groovy, Scala or anything else.

More details will come as soon as the closing keynote session recording will be published.

Remembering Shawn Pearce and his legacy

Dave Borowitz, the leader of the Gerrit Code Review project, made a thoughtful and touching speech about Shawn Pearce, the father of the Gerrit 2, who started the project exactly 10 years ago. The cake, the hackathon, the summit, and the v2.16 release have been fully dedicated to his memory as appreciation for his humanity and passion for OpenSource.

Thanks, Shawn. We will continue on your legacy and improve the Gerrit Code Review platform as you would have wanted us to do.