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Portal:Data Services/Admin/Wiki Replica DNS

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The Wiki Replica servers use service names managed by the Cloud VPS Designate API to expose databases to Cloud Services users. The /usr/local/sbin/wmcs-wikireplica-dns script is used to create and update these service names. These operations are performed from the currently active cloudcontrol server (typically cloudcontrol1003.wikimedia.org).

Changing the backend server for a shard

The /etc/wikireplica_dns.yaml config file tells wmcs-wikireplica-dns which IPs to map to which service names. This file is managed by Puppet using the source file found at modules/openstack/files/util/wikireplica_dns.yaml. Management is done at the granularity of a shard.

To change the backend server for one or more shards, edit the yaml config file and then run:

$ ssh cloudcontrol1003.wikimedia.org
$ source <(sudo cat ~root/novaenv.sh)
$ wmcs-wikireplica-dns

Calling the script with no arguments will simply refresh/create all the records from the config file.

Adding a new wikidb alias

Aliases for each wikidb in each zone are made based on the wikidb mappings found in the s[1-8].dblist files managed in operations/mediawiki-config.git. The current values are read from https://noc.wikimedia.org/conf/ at runtime.

When a new wikidb is added or moved between shards, update the related <wikidb>.{analytics,web}.db.svc.eqiad.wmflabs CNAME records. Limiting the run to a single shard will be significantly faster unless the shard is s3 which has most of the aliases.

$ ssh cloudcontrol1003.wikimedia.org
$ source <(sudo cat ~root/novaenv.sh)
$ wmcs-wikireplica-dns --aliases [--shard <sN>]

See also