search-api: Content in the search index and where it comes from
For an overview view of the sorts of content that are available, see Document types on GOV.UK.
This is what most publishers use to publish. Content appears on the "inside government" part of GOV.UK. There are 200,000 documents.
Implemented in searchable.rb.
Other publishing apps
Most publishing apps, such as publisher and specialist-publisher, do not send content to Search API directly. Instead, they publish content to the publishing-api which adds the content to a notifications queue to be ingested by search-api.
See ADR 001 for more details on this approach.
Admin for GOV.UK search. Publishes "recommended links" to Search API, so we can show external links in search results; and "best bets", so selected search results can be artificially boosted to the top of the list.