Notify

Notify is a microservice which uses Redis and a JWT user_id claim to provide state and broadcast delivery over a websocket interface.

A JWT user_id claim was chosen to avoid database lookups. Redis is used to retrieve an initial state object on a websocket connection, as well as subscribing to a per-user topic.

How it works?

The session ID JWT claims must include a user_id claim (string). The user ID is then mapped to individual redis keys:

• notify:%s - a publish/subscribe channel for broadcasts
• notify:%s:state - a hash value (e.g. [unread_messages => 1, ...])

Broadcasting to the Redis channels can be done from your own applications directly. Twirp RPC API endpoints are also provided for convenience.

Additionaly a set of topics can be provided and the session will be subscribed to notify_topic:%s channels.

Building

Notify uses Docker and Drone CI. In order to build a notify binary for amd64 you need to do two things:

• cd docker/build && make - this creates a build image with needed dependencies,
• make - this runs the full Drone CI suite and produces a binary under /build

Testing

You can use the provided docker-compose.yml to run a test instance of notify, as well as a keydb redis-compatible service. In order to make your life a bit easier, a few shorthand commands are provided:

• make up - runs the compose services,
• make down - stops/removes the compose services,
• make logs - tails logs for the compose services,

The testing service is exposed on port 1234, by default the microservice is listening to port :3000, and also provides a pprof listener on :6060. Both addresses can be overriden with environment variables PORT and PPROF_PORT respectivelly.

Miscellaneous

It's possible to extend the microservice to:

• Provide other kinds of authorization (e.g. Pareto, SQL, ...)
• Use different kinds of queues (e.g. Kafka, zeromq, ...)
• Use a different key/value store (e.g. Memcache, SQL, ...)

These are very specific needs that aren't currently implemented. If you'd like to sponsor development, send me an e-mail.