Change Details

Apologies in advance if this is tracked elsewhere but I didn't find anything on Phabricator :) It happened more than once that while debugging some mediawiki memcache errors reported in logstash I came across reference to nutcracker, like the following: https://logstash.wikimedia.org/app/kibana#/doc/logstash-*/logstash-2019.01.21/mediawiki?id=AWhum3hkzpjgITg6U7ZH&_g=h@44136fa A quick grep in mediawiki config reveals other things (the Redis bits are hidden): ``` wmf-config/mc-labs.php:$wgMainCacheType = 'nutcracker+mcrouter'; wmf-config/mc-labs.php:$wgObjectCaches['nutcracker-memcached'] = [ wmf-config/mc-labs.php:$wgObjectCaches['mcrouter+nutcracker'] = [ wmf-config/mc-labs.php: // old nutcracker consistent hash scheme (uses shard tag); wmf-config/mc-labs.php: 'args' => [ 'nutcracker-memcached' ], wmf-config/mc-labs.php:$wgObjectCaches['nutcracker+mcrouter'] = [ wmf-config/mc-labs.php: 'args' => [ 'nutcracker-memcached' ] wmf-config/mc-labs.php: 'args' => [ 'mcrouter+nutcracker' ] wmf-config/mc.php: ? [ '/var/run/nutcracker/nutcracker.sock:0' ] wmf-config/mc.php: $wgMainCacheType = 'memcached-pecl'; // nutcracker only; no mcrouter present ``` Would it be possible to do a final clean up? If not, can we check if logstash errors like the above are problematic or not?

This task was originally meant only to remove nutcracker from the MediaWiki's config, but why not be bold and expand its scope! Nutcracker is currently used in the following: [ ] MediaWiki's config - its only usage is for wikitech [ ] Thumbor The configuration on app/api appservers for memcached has been removed with https://gerrit.wikimedia.org/r/#/c/operations/puppet/+/510697, and it will get applied upon the next round of reboots (so nutcracker will restart without impacting the session handling in Redis). We have tested the change in canaries and nothing weird has been noticed/reported/found. The idea for this task is to migrate tools using nutcracker to mcrouter (if possible) to avoid maintaining in the long run two code bases (the nutcracker's one is basically abandoned).

Apologies in advance if this is tThis task was originally meant only to remove nutcracked elsewhere but I didn't find anything on Phabricator :)r from the MediaWiki's config, but why not be bold and expand its scope! It happened more than once that while debugging some mediawiki memcache errors reported in logstash I came across reference to nutcracker, likeNutcracker is currently used in the following: https://logstash.wikimedia.org/app/kibana#/doc/logstash-*/logstash-2019.01.21/mediawiki?id=AWhum3hkzpjgITg6U7ZH&_g=h@44136fa A quick grep in mediawiki config reveals other things (the Redis bits are hidden): ``` wmf-config/mc-labs.php:$wgMainCacheType = 'nutcracker+mcrouter'; wmf-config/mc-labs.php:$wgObjectCaches['nutcracker-memcached'] = [ wmf-config/mc-labs.php:$wgObjectCaches['mcrouter+nutcracker'] = [ wmf-config/mc-labs.php: // old nutcracker consistent hash scheme (uses shard tag); wmf-config/mc-labs.php: 'args' => [ 'nutcracker-memcached' ], wmf-config/mc-labs.php:$wgObjectCaches['nutcracker+mcrouter'] = [ wmf-config/mc-labs.php: 'args' => [ 'nutcracker-memcached' ] wmf-config/mc-labs.php: 'args' => [ 'mcrouter+nutcracker' ] wmf-config/mc.php: ? [ '/var/run/nutcracker/nutcracker.sock:0' ] wmf-config/mc.php: $wgMainCacheType = 'memcached-pecl'; // nutcracker only; no mcrouter present[ ] MediaWiki's config - its only usage is for wikitech ```[ ] Thumbor Would it be possible to do a final clean up?The configuration on app/api appservers for memcached has been removed with https://gerrit.wikimedia.org/r/#/c/operations/puppet/+/510697, If not,and it will get applied upon the next round of reboots (so nutcracker will restart without impacting the session handling in Redis). can we check if logstash errors like the above are problematic or not?We have tested the change in canaries and nothing weird has been noticed/reported/found. The idea for this task is to migrate tools using nutcracker to mcrouter (if possible) to avoid maintaining in the long run two code bases (the nutcracker's one is basically abandoned).