Since 2018-11-26 13:56 there is lots of:
ErrorException from line 1159 of /srv/mediawiki/php-1.33.0-wmf.4/includes/Message.php: PHP Warning: Invalid argument supplied for foreach() only on enwiki:
https://logstash.wikimedia.org/goto/9e9e2feef0cad33bd45e2b70a18085d7
I don't see any deployment at the time. Other errors that seem related:
/srv/mediawiki/php-1.33.0-wmf.4/includes/Message.php: PHP Notice: Undefined variable: key /srv/mediawiki/php-1.33.0-wmf.4/includes/Message.php: PHP Notice: Undefined variable: message
and maybe:
[{exception_id}] {exception_url} ErrorException from line 302 of /srv/mediawiki/php-1.33.0-wmf.4/includes/Message.php: PHP Notice: Unable to unserialize: [a:8:{s:9:"interface";b:1;s:8:"language";s:2:"en";s:3:"key";s:30:"wikimediashoplink-link-tooltip";s
This may be overloading Elastic, or at least generating an alert:
[2018-11-27 10:20:33] SERVICE ALERT: icinga1001;Logstash rate of ingestion percent change compared to yesterday;CRITICAL;HARD;5;523 ge 130