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== Summary ==
#REDIRECT [[Incidents/20160407-Mediawiki]]
All Mediawiki servers were serving mostly HTTP 5XX for about 5 minutes at 1350 UTC
== Timeline ==
* 13:50 UTC: switch CirrusSearch traffic to codfw, with a buggy configuration (see for the correction)
* almost immediate raise in HTTP 5XX errors to 400K errors / minute
* 13:53 UTC: rollback
* 13:55 UTC: error rate back to reasonable level
== Conclusions ==
# unit testing wmf-config is hard
# testing configuration changes related to datacenter is not possible on labs
# carefully testing this kind of change on test nodes (mw1017/mw1099/mw2017/mw2099) is the minimum required
== Actionables ==
Immediate issues have been addressed. This incident is mainly about human error (mine) and insufficient testing (me again).
* a standardized and automated canary test system would help mitigate this kind of issues, but is probably a long term action outside of the scope of a post incident action.
[[Category:Incident documentation]]

Latest revision as of 17:45, 8 April 2022