Topic on Talk:GitLab/2020 consultation

The Gerrit multi-site plugin README was out of date and misstated its support for multi-write. See: https://gerrit-review.googlesource.com/c/plugins/multi-site/+/285782/3/README.md

What is written in the conclusion is not accurate, with regards to the multi-site capabilities:

"We are unique in the community of Gerrit users which include large companies such as SAP, Ericsson, Qualcomm, and Google. Google, in particular, is singular in their use of Gerrit for projects like Android and Chromium. To support these large, open projects multi-site capabilities are needed; however, much of that work is either closed-source or does not support multi-site writes".

If you follow the multi-site link you will see that the multi-site plugin is open-source, supports multiple writes from all sites and is able to prevent split-brains.

GerritHub.io has been multi-site for over one year.

I even wrote a task on phabricator about this: https://phabricator.wikimedia.org/T217174

Looking at the README on the multisite page the quote on the page is, "Currently, the only mode supported is one primary read/write master and multiple read-only masters but eventually the plan is to support multiple read/write masters."

We currently have one main gerrit sync'd with a replica. It seems that the multi-site plugin will not currently support two gerrit's being written to simultaneously without partitioning: is that accurate?

Seems this has been fixed with https://gerrit-review.googlesource.com/c/plugins/multi-site/+/285782

That comment on the README.md is stale and misaligned with the DESIGN.md. The multi-site plugin supports multiple sites in read/write and correctly prevent split-brains in case of two users pushing concurrently on the same repo on the same branch from two remote sites on the globe.

I have addressed the stale comment with a change for review, thanks for pointing that out :-)

With regards to the problems in migrating to newer versions of Gerrit, I do recognise that it has been difficult until v3.0. You guys are not far from the "tipping point" and I would be more than happy to help, as I did with the Eclipse Foundation and I am doing with the OpenStack project.

Also, the multi-site setup, allows Gerrit canary deployments because supports, from v3.0 onwards, different sites with different versions of Gerrit (typically the version +1).

Since the introduction of multi-site on GerritHub.io, we went from 99.9% uptime to > 99.99% uptime, and never declared a "planned outage" for any of our upgrades.

I would be more than happy to help the Wikimedia Foundation to get there as well.

Luca.

Hi @TCipriani (WMF) the multi-site README.md has been updated, thanks for the reviews. Can you also update the relevant section in the GitLab consultation? Thanks a lot for pointing this out.

Luca.

Done. Thanks for the update.