@Jdlrobson, @phuedx, any help you can provide would be very appreciated. The bare minimum of changes needed are:

$wgWBClientSettings[ 'pageSchemaNamespaces' ] = [ 0 ];
$wgWBClientSettings[ 'pageSchemaSplitTestSamplingRatio' ] = 0.5;
$wgWBClientSettings[ 'pageSchemaSplitTestBuckets' ] = [ 'control', 'treatment' ];

I'm hoping it'll kind of just work with the beta Wikidata instance but additional settings are described in the task in the event that it doesn't.

With respect to the last note, maybe @phuedx can help us out in the absence of @pmiazga

You'll need to link pages on the beta cluster with the wikidata beta cluster

I'm not sure if this functionality is broken right now or not. It does not work in development (see T205922, T206567). A link seems to be made automatically for pages that have the same name as the Q item like, "kitten", when I override $wgWBClientSettings[ 'siteGlobalID' ] = 'enwiki';. The BC is currently down but hopefully there's a kitten entry there, possibly Q147, and Kitten will automatically link there when it comes back without changes to siteGlobalID but this might require some fiddling and perhaps shouldn't be attempted until T208809 is resolved.

☝️

• A SWAT will be needed to turn it on. Given this is a beta cluster only change, if you find a willing deployer, you can do it outside the normal SWAT windows.

The config is automatically deployed to the Beta Cluster when a config change is merged by the beta-mediawiki-config-update-eqiad Jenkins job.

In T208763#4724047, @phuedx wrote:

☝️

• A SWAT will be needed to turn it on. Given this is a beta cluster only change, if you find a willing deployer, you can do it outside the normal SWAT windows.

The config is automatically deployed to the Beta Cluster when a config change is merged by the beta-mediawiki-config-update-eqiad Jenkins job.

yes, but someone still has to keep the repository's files in sync in production, or the next deployer in production can throw the change out

Change 471948 had a related patch set uploaded (by Phuedx; owner: Phuedx):
[operations/mediawiki-config@master] BC: Enable Schema.org page split test

https://gerrit.wikimedia.org/r/471948

Please review ☝️, especially for precision of language.

@Niedzielski: You'll note that I've put (what I consider to be) safe defaults in wmf-config/Wikibase.php. These defaults will be set for all wikis. If they aren't safe, then please LMK!

I've scheduled rOMWC61479ef8e135: BC: Enable Schema.org page split test for deployment during the Morning SWAT window as I might not be available for the entirety of the European Mid-day SWAT window.

I've rescheduled the change to be deployed in the European Mid-day SWAT window.

Change 471948 merged by jenkins-bot:
[operations/mediawiki-config@master] BC: Enable Schema.org page split test

https://gerrit.wikimedia.org/r/471948

Mentioned in SAL (#wikimedia-operations) [2018-11-07T12:36:36Z] <zfilipin@deploy1001> Synchronized wmf-config: SWAT: [[gerrit:471948|BC: Enable Schema.org page split test (T208763)]] (duration: 00m 54s)

This took a little while to test! However, after linking Q390678 to the Foooooo article on the Beta Cluster I see the following at the bottom of that article:

{
  "@context": "https://schema.org",
  "@type": "Article",
  "name": "Foooooo",
  "url": "https://en.wikipedia.beta.wmflabs.org/wiki/Foooooo",
  "sameAs": "http://www.wikidata.org/entity/Q390678",
  "mainEntity": "http://www.wikidata.org/entity/Q390678",
  "author": {
    "@type": "Organization",
    "name": ""
  },
  "publisher": {
    "@type": "Organization",
    "name": "",
    "logo": {
      "@type": "ImageObject",
      "url": ""
    }
  },
  "datePublished": "2014-01-02T23:05:11Z",
  "dateModified": "2014-01-02T23:05:11Z",
  "image": "https://upload.beta.wmflabs.org/wikipedia/commons/4/4e/Www_2014-01-02_15-04.png",
  "headline": "gcdXUtUqFgyFrCpkeZYw"
}

Are the odd values in the author and publisher fields are a consequence of not having set some system messages on the Beta Cluster?

I can also confirm that I don't see the above type of output on the bottom of all articles with linked Wikidata items (again, on the Beta Cluster).

I also confirmed that no new entries were logged to Logstash using the X-Wikimedia-Debug tool, e.g. https://logstash.wikimedia.org/app/kibana#/dashboard/x-debug?_g=h@7bf0c26&_a=h@c44cdd9

verified on beta cluster, works as expected.