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User:Effie Mouzeli (WMF)/Docs/Deployment

From Wikitech

Where should we go

Issues we have now

  • We currently don't have a "mediawiki version"
  • <user> We are taking over mediawiki-config deployment for the s3 failover, please talk to us before deploying anything

Scap

Sources distributed to appservers

  • mediawiki-config
  • various subdirectories named php-1.XX.YY-wmf.Z
  • PrivateSettings.php which is managed by puppet
  • possibly security patches
  • symlinks like php => php-1.XX.YY-wmf.Z

Concerns

  • some things need to be deployed to 100% fast (eg depooling db servers), where scap file is useful
  • caches -> opscache, varnishcache, parsercache, mediawiki-config cache

Misc ideas

  • what if we keep a version tag/number/whatever for each repo
  • keep a "scap run" number on each server
  • we don't need a percentage of traffic for sync-file/sync-dir only for full scap sync
    • sync-file is still needed, e.g., a memcached server goes down during train and we do a percentage based rollout (which takes some time) we'll need to run a sync file during the train
  • we may be able to get atomic rollouts for free with php7
  • keep individual versions of each repo, i.e., scap can figure out changes
  • canary deploys for train, i.e., scap train command
  • a mediawiki deploy directory vs a mediawiki config directory, so what's deployed is the individual states of multiple deployed repositories
  • we could progressively rollout wikimediaversions with a new scap subcommand for train deploys
  • could use canaries during the train keeping Tues-Thursday the same wrt to the train except using a progressive rollout
  • Scope of focusing on sync-wikiversions would be train-only
    • we should combine this with restructuring of repos
  • If we are able to have something that indicates which version is deployed/running, a server could check every X minutes if it is running the proper version, and if yes, do a scap pull

Decoupling

  • operational state - this eventually moves to a local proxy
  • deployment state - wikiversions, symlinks
  • mediawiki code & translation caches
  • everything else?
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