The mobileapps service (a.k.a. "mobile content service") provides a facade through which Wikimedia page content is requested, modified to remove unnecessary bits, and put into a form tailored for use by mobile clients. The underlying content is primarily Parsoid HTML fetched via the REST API, modified, and then stored in RESTBase for retrieval via the
/page/mobile-html and other PCS endpoints.
Mobileapps runs on the Kubernetes cluster. Use of content provided by mobileapps was rolled out incrementally to Wikipedia Android app users in early 2016. The service currently provides article content for all users of the Android and iOS apps. It also provides the summary endpoint for Page Previews on web, and the native apps.
The mobileapps service is maintained primarily by the Wikimedia Product Infrastructure team, with support from the Core Platform Team team. Mentioning mobileapps in IRC on the ops channel should get their attention. If not you can mention individual team members on the #wikimedia-infrastructure IRC channel.
Consequences of shutdown/failure
Page content and page previews on the Android and iOS apps would not be affected, maybe not immediately since this is behind RESTBase but eventually when pages get edited. (There is no fallback in the Android app anymore.) Same for page previews on web.
Wikimedia REST API mobile endpoints (link is to enwiki, but the endpoints are the same for all Wikipedias)
PCS: summary, mobile-html and related endpoints
MCS: mobile-sections* endpoints
Refresh RESTBase cache for mobileapps for troubleshooting and fighting vandalism tips