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The Deployment Train is a weekly process led by the Release Engineering Team, to deploy the latest alpha version of MediaWiki at WMF to production.

Typical numbers as of September 2021:

  • 198 code repositories (mediawiki/core, mediawiki/vendor, 188 MW extensions, and 8 MW skins).
  • 978 wikis.
  • between 150 and 1000 patches since the last train.

Current week


See also MediaWiki 1.41/Roadmap on
Deployment train diagram.
Sunday Monday Tuesday Wednesday Thursday Friday Saturday
Deploy to group 0 Deploy to group 1 Deploy to group 2



Each Tuesday a Release Engineering team member cuts a new branch of all 198 repositories in a Wikimedia Production deployment. The branch is always prefixed with wmf/ and then a version number. For example: wmf/1.40.0-wmf.1.

The train conductor deploys that to Group0 wikis (see dblists/group0.dblist). This group includes:


On Wednesday Release Engineering leads a log triage session to find and file any new errors.

Following the log triage, the train conductor for the week makes a go/no-go decision to deploy to Group1 wikis.

Group1 is non-Wikipedias, see dblists/group1.dblist.

Group1 includes:


If no blockers are found, the train conductor pushes code to all other Wikipedias, see dblists/group2.dblist.

Group2 includes (English Wikipedia).