go-bsky-feed-generator

A minimal implementation of a BlueSky Feed Generator in Go

Requirements

To run this feed generator, all you need is docker with docker-compose.

Running

Start up the feed generator by running: make up

This will build the feed generator service binary inside a docker container and stand up the service on your machine at port 9032.

To view a sample static feed (with only one post) go to:

http://localhost:9032/xrpc/app.bsky.feed.getFeedSkeleton?feed=at://did:plc:replace-me-with-your-did/app.bsky.feed.generator/static

Update the variables in .env when you actually want to deploy the service somewhere, at which point did:plc:replace-me-with-your-did should be replaced with the value of FEED_ACTOR_DID.

Accessing

This service exposes the following routes:

/.well-known/did.json
- This route is used by ATProto to verify ownership of the DID the service is claiming, it's a static JSON document.
- You can see how this is generated in pkg/gin/endpoints.go:GetWellKnownDID()
/xrpc/app.bsky.feed.getFeedSkeleton
- This route is what clients call to generate a feed page, it includes three query parameters for feed generation: feed, cursor, and limit
- You can see how those are parsed and handled in pkg/gin/endpoints.go:GetFeedSkeleton()
/xrpc/app.bsky.feed.describeFeedGenerator
- This route is how the service advertises which feeds it supports to clients.
- You can see how those are parsed and handled in pkg/gin/endpoints.go:DescribeFeeds()

Publishing

Once you've got your feed generator up and running and have it exposed to the internet, you can publish the feed using the script from the official BSky repo here.

Your feed will be published under your DID and should show up in your profile under the feeds tab.

Architecture

This repo is structured to abstract away a Feed interface that allows for you to add all sorts of feeds to the router.

These feeds can be simple static feeds like the pkg/feeds/static/feed.go implementation, or they can be much more complex feeds that draw on different data sources and filter them in cool ways to produce pages of feed items.

The Feed interface is defined by any struct implementing two functions:

type Feed interface {
	GetPage(ctx context.Context, feed string, userDID string, limit int64, cursor string) (feedPosts []*appbsky.FeedDefs_SkeletonFeedPost, newCursor *string, err error)
	Describe(ctx context.Context) ([]appbsky.FeedDescribeFeedGenerator_Feed, error)
}

GetPage gets a page of a feed for a given user with the limit and cursor provided, this is the main function that serves posts to a user.

Describe is used by the router to advertise what feeds are available, for foward compatibility, Feeds should be self describing in case this endpoint allows more details about feeds to be provided.

You can configure external resources and requirements in your Feed implementation before Adding the feed to the FeedRouter with feedRouter.AddFeed([]string{"{feed_name}"}, feedInstance)

This Feed interface is somewhat flexible right now but it could be better. I'm not sure if it will change in the future so keep that in mind when using this template.

This has since been updated to allow a Feed to take in a feed name when generating a page and register multiple aliases for feeds that are supported.