ld-relay

Assuming their (also open source) Relay Proxy[1] can connect to this successfully, the disclaimers about lack of HA might not be too concerning. We already run a giant pool of relays for our apps to connect to, both to save ingress/egress costs, and to provide a backup if LD blips out for a while. [Edit: yep, it actually uses the Relay Proxy, in offline mode. See https://github.com/dorklyorg/dorkly/wiki/5.-Architecture] [1] https://github.com/launchdarkly/ld-relay

This looks really great! Would have loved something like this a couple of years ago before rolling our own, this would have saved so much time and effort. Borrowing a lot of LaunchDarkly's playbook for feature flagging will serve you well here. Server Sent Events and providing a self host-able "relay proxy"[1] will be extremely valuable in terms of perf and redundancy. [1] https://github.com/launchdarkly/ld-relay

We've thought quite a bit about how to make this work as a service. The key to our architecture is that evaluating a feature flag for a user does not involve a remote call. We make that work by embedding a rule evaluation engine in our SDKs. When you request a flag, the user is compared against these rules (in memory) and served the appropriate variation. We then use a streaming API to serve rule changes, so when you make a change to your dashboard, the new rules are streamed to all your backend servers within a few hundred milliseconds. If you need even more resiliency, you can deploy a small service in your own infrastructure (https://github.com/launchdarkly/ld-relay) that allows you to persist these flag configurations in Redis.