Some background that I am familiar with because I worked on the team that maintains Wikimedia's Gerrit, GitLab, Phabricator, CI and deployment systems. I left in 2022, however, by then the GitLab migration was well underway.
As far as I remember, and from what I observed, the decision to adopt GitLab was meant to better cater to newcomers and volunteers who generally do not appreciate Gerrit and saw it as a serious barrier to engaging with the Wikimedia software development ecosystem. Gerrit has a pretty steep learning curve and the web interface is pretty ugly (Subjective, but this is an opinion shared by many.) We got quite a bit of feedback that Gerrit was a stumbling block for new contributors as well new hires on the Product and Engineering teams. Many folks who have used Gerrit for a long time learn to love it but newcomers either hated it or found it difficult to adjust to.
So to summarize the main arguments for GitLab (as apposed to "just use github" or various other alternatives which were considered):
* It's ostensibly open
* It's similar to GitHub in most ways that matter
* The GitLab CI system is configured in the repo and it's entirely self-service, as apposed to the mess that is Gerrit + Jenkins + Zuul CI. Zuul requires a lot of specialty expertise to configure and maintain, and that places control of CI largely out of the hands of the people maintaining each repo. Self serve is better for the needs of many if not most developers.
* Last but certainly not least, there was a fairly wide-spread fear that Microsoft would ruin GitHub, along with and a strong preference for self-hosted free software tools in keeping with https://foundation.wikimedia.org/wiki/Resolution:Wikimedia_F...
As far as I remember, and from what I observed, the decision to adopt GitLab was meant to better cater to newcomers and volunteers who generally do not appreciate Gerrit and saw it as a serious barrier to engaging with the Wikimedia software development ecosystem. Gerrit has a pretty steep learning curve and the web interface is pretty ugly (Subjective, but this is an opinion shared by many.) We got quite a bit of feedback that Gerrit was a stumbling block for new contributors as well new hires on the Product and Engineering teams. Many folks who have used Gerrit for a long time learn to love it but newcomers either hated it or found it difficult to adjust to.
So to summarize the main arguments for GitLab (as apposed to "just use github" or various other alternatives which were considered):
* It's ostensibly open * It's similar to GitHub in most ways that matter * The GitLab CI system is configured in the repo and it's entirely self-service, as apposed to the mess that is Gerrit + Jenkins + Zuul CI. Zuul requires a lot of specialty expertise to configure and maintain, and that places control of CI largely out of the hands of the people maintaining each repo. Self serve is better for the needs of many if not most developers. * Last but certainly not least, there was a fairly wide-spread fear that Microsoft would ruin GitHub, along with and a strong preference for self-hosted free software tools in keeping with https://foundation.wikimedia.org/wiki/Resolution:Wikimedia_F...