- All current EventLogging bugs are resolved and data is confirmed by @Tbayer (see T162672#3496940)
- Tracking task for @Tbayer's analysis: T158172: Analyze results of stage 0 page previews test
- Deployment must happen after green light from @ovasileva (see T162672#3496940)
- Reset the instrumentation sampling rate to 0.001 for all wikis, i.e. revert rOMWCd5c4bd728014: pagePreviews: Increase instrumentation sampling rate.
- Deployment must happen in few stages (3 or more) in order to make rollback easier – if we start overloading the edge caches (and origin servers potentially), say.
- Deploy to a chunk of 50 wikis and assess the impact on Page Previews, RESTBase, and Varnish performance, if any.
- If there's no significant impact, then increase the chunk size to 100/150/200.
- Ensure that the EventLogging instrumentation is disabled for the chunk.
- The Ops and Services teams are notified after each deploy.
- We pause for a day (at least) between deploys so that each team has a chance to observe the effect of increased load.
Thursday, 3rd August: The first 50 wikis (in alphabetical order) from the list were deployed to 🎉🎉🎉
Monday, 21st August: Page Previews is currently deployed to all wikis but enwiki and dewiki 🎉🎉🎉
For each rollout (in sets of 50?), select 5 wikis with different scripts:
For each wiki:
- Go to the main page of the wiki and hover over a couple of links, ensure previews appear
- Open a new page by selecting the preview, ensure page opens
- On new page, ensure previews appear
- Hover over an article containing disambiguation text, ensure disambiguation text does not appear in preview
- If the script is rtl, ensure preview appears rtl and the settings cog is placed accordingly
For a single wiki:
- Disable previews using settings cog, ensure previews are disabled
- Re-enable previews using link in footer, ensure previews appear again
- Log in, enable previews, ensure previews appear
- Disable previews, ensure previews do not appear
- Ensure previews are NOT enabled on dewiki and enwiki
- Ensure previews are enabled on ruwiki