What a site offers

Anahita is small services, each doing one thing, and a site runs and shows only what it offers. One file says what that is: instance.json, beside the files that say what each kind of profile has. An instance is one big profile, and every profile on it has only what it has. A site of notes and photos alone, for example, offers no articles, topics, events, websites or videos: they are in no composer, menu or tab, and the services refuse them.

Built for the recipes, roadmap row 139 (the plan (opens in a new tab)).

The file

instance.json in the directory ACTOR_FEATURES_PATH names, /app/defaults/actor_features in graph-grpc-service's image, beside default.json, person.json, group.json, event.json and website.json (Permissions). It is in their form: a list of services, each with the kinds it offers.

[
  { "service": "actor-service", "node_types": ["person", "group"] },
  { "service": "text-service",  "node_types": ["note"] },
  { "service": "photo-service", "node_types": ["photo"] },
  { "service": "video-service", "enabled": false }
]

That is a site of people and groups, notes and photos.

In the file	Means
A service with node_types	That service, with those kinds alone
A service with "enabled": false	Not that service at all
A service not listed	As each kind of profile's own file says
No file	Everything, as before it was read. The image carries none

actor-service's kinds are the kinds of profile that may be made: group, event, and website, which syndication-service makes. A person is always offered: it is an account. The kinds of post are note, article and topic (text-service), photo (photo-service), and video and audio (video-service).

A file that cannot be read is said in graph-grpc-service's log, and offers everything, as no file does.

What follows from it

1. Every profile has only what the instance offers, whatever its kind's file or its own saved choices say: its composers and tabs, and who may add each kind, come from those features, so a kind that is off is neither shown nor taken.
2. The services refuse what is off, with 403 {"error": "off"}: actor-service a group or an event, syndication-service a website, text-service a note, an article or a topic, photo-service a photo, and video-service a video or a sound. graph-grpc-service refuses to save a post of a kind that is off, whichever service asks, as a last check. GROUPS_FROM, EVENTS_FROM and WEBSITES_FROM still say who may make one where it is offered.
3. What is already there stays, readable at its address: a site that turns articles off keeps those written before.
4. Posts from other servers are shown as they are: an article from the fediverse still shows in a feed. This is about what is made here.
5. NodeInfo says what is offered, in metadata.offers: {"profiles": ["person", "group"], "posts": ["note", "photo"]}. The web app follows it: its menu (Groups, Events, Websites), a group's Events tab, the recommendations' tabs, and the buttons that make a group, an event or a website.

Video and sound

VIDEO_UPLOADS and AUDIO_UPLOADS go together with the file: video is offered where the file offers it and VIDEO_UPLOADS is on, sound the same with AUDIO_UPLOADS (Configuration). A site that set them changes nothing. NodeInfo's videoUploads and audioUploads say both together.

Giving a site its own

graph-grpc-service alone reads the file; every other service asks it (ReadInstance, on the graph's gRPC service), so there is one file in one place.

1. docker-compose: graph-grpc-defaults/actor_features/ is mounted into graph-grpc-service; put instance.json there. It is read again for each request: no restart.
2. Kubernetes: mount a ConfigMap of the file over /app/defaults/actor_features/instance.json in graph-grpc-service's Deployment, with subPath, so that the image's other files stay. A recipe does this in its overlay.

Where the code is

What	Where
Reading the file, cutting a profile's features, what is offered	graph-grpc-service/data/actor_features/instance.go, merger.go (ForSite)
ReadInstance, and the last check on saving a post	graph-grpc-service/cmd/server/handlers/instance.go
Asking, and refusing with off	anahita-libs/data/services/graph_grpc.go (ReadInstance, Offered), anahita-libs/handlers/offered.go
NodeInfo's offers	auth-service/cmd/api/handlers/node_info.go
The web app	src/utils/offers.js, src/permissions/actor.js (anahita-web)