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Incident documentation/2017-06-16 PHAB
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Phabricator was down for approximately 8 minutes due to an unintentional/badly executed upgrade.
- At approximately 13:18 UTC, I (User:20after4) attempted to fix a minor bug in a phabricator extension (https://phabricator.wikimedia.org/T168058) by deploying https://phabricator.wikimedia.org/rPHEX721eca9b64cc38b495a255bad46cbe11f3d5c390.
- Instead of cherry-picking the dependent change, the code was mistakenly fast-forwarded to a version which depended on new database migrations.
- 13:19 UTC - icinga alerts and several people notice that phabricator is displaying a setup error page instead of the normal application.
- 13:20 UTC - I !log in #wikimedia-operations to let people know that I'm working on it.
- Because phabricator makes it easier to roll forward than to roll back, and my experience that migrations are usually fast, I ran the storage upgrade script to apply the migrations.
- 13:22 UTC - I acknowledged the icinga alert to prevent further paging.
- The script (phabricator/resources/sql/autopatches/20170528.maniphestdupes.php) was moderately large and slow compared to most phabricator migration scripts so this took several minutes to complete
- 13:25 UTC - Service restored.
- Almost every update to Phabricator requires database migrations to be applied. These are usually quite fast but not always.
- Don't attempt code changes on friday, even trivial ones.
- Always assume that code will have unexpected dependencies.
- All upgrades, even minor ones should be during the scheduled window.
- jynus requested that I coordinate with him to schedule the database slave to be offline when running migrations.
- I will file a task to remind about this (https://phabricator.wikimedia.org/T187143)