Wikimedia Release Engineering Team/Trainsperiment week/gu
 | This page is obsolete. It is being retained for archival purposes. It may document extensions or features that are obsolete and/or no longer supported. Do not rely on the information here being up-to-date. The conclusion of this experement can be found in a blog post on Phabricator. |
🚂🧪 Trainsperiment Week - March 21, 2022.
Four deployment trains. One week. Six nervous Release Engineers!
આ શું છે!?
The "deployment train" is the name of the process where the Release Engineering Team (RelEng) deploys between 150–950 patches to the ~980 Wikimedia wikis, in 3 stages. There is usually one train each week.
There will be four deployment trains during the week of Monday, 21 March 2022.
This is a one-week experiment to gather data for possible future changes.
If you have ideas or thoughts, please add them on the talk page. 💡
Visualization
These images show the difference between the regular process and this new experimental process:
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Old cadence vs mainlinemediawiki/core -
Old cadence vs mainlinemediawiki/corewith deployment metrics labeled -
New cadence vs mainlinemediawiki/core
🤔 Unknowns
Here is a list of things we are thinking about. If you can help with any of these: please talk to us!
- How will more trains affect caches and site performance? (T303758)
- Are developers going to need to be more mindful of forward and backward compatibility? (T303759)
- How will train-rollback work with blockers? This one is on us, but we’ll be figuring it out as we go. (T303747)
- Will blocker tasks be too confusing with so many trains?
- Is this sustainable?
🏆 Goals
Our goal is a shorter time between when developers write code and when that code gets live traffic. We believe the benefits of that are:
- A more accurate mental model of the current state of the code that is "live" will make development easier
- A smaller amount of code per release, will make the releases easier to debug and test
- It will make it easier for developers to fix bugs in a release if the context is still fresh in their heads
📅 Schedule
Monday, 21 March 2022 #
| Window | Date Time | Event | Signup to join the hangout |
|---|---|---|---|
| Branch Cut | 21 Mar 2022 02:00UTC | 1.39.0-wmf.1 Branch Cut | N/A (it's automatic) |
| UTC AM Train | 21 Mar 2022 09:00UTC |
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| Branch Cut | 21 Mar 2022 12:00UTC | 1.39.0-wmf.2 Branch Cut | N/A (it's automatic) |
| UTC PM Train | 21 Mar 2022 18:00UTC |
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Tuesday, 22 March 2022 #
| Window | Date Time | Event | Signup to join the hangout |
|---|---|---|---|
| Branch Cut | 22 Mar 2022 02:00UTC | 1.39.0-wmf.3 Branch Cut | N/A (it's automatic) |
| UTC AM Train | 22 Mar 2022 09:00UTC |
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Wednesday, 23 March 2022 #
| Window | Date Time | Event | Signup to join the hangout |
|---|---|---|---|
| Branch cut | 23 Mar 2022 02:00UTC | 1.39.0-wmf.4 Branch cut | N/A (it's automatic) |
| UTC PM Train | 23 Mar 2022 18:00UTC |
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Thursday, 24 March 2022 #
| Window | Date Time | Event | Signup to join the hangout |
|---|---|---|---|
| UTC AM Train | 24 Mar 2022 08:00UTC |
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| UTC PM Train | 24 Mar 2022 18:00UTC |
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Outcomes
A postmortem on the experiment including summaries of feedback received has been published as What We Learned from Trainsperiment Week in the Release Engineering team's blog Doing the needful.