Overview
This topic explains the LaunchDarkly Relay Proxy, a small service that runs in your own infrastructure. It connects to LaunchDarkly and provides endpoints to service SDK requests and the ability to populate persistent stores.
Resources and documentation:
Use cases
This table lists common use cases for the Relay Proxy:
| Name | Description |
|---|---|
| Restart resiliency for server-side SDKs | LD Relay acts as an external cache to server-side SDKs to provide flag and segments rules |
| Reduce egress and outbound connections | LD Relay can service initialization or streaming requests from SDKs instead of having them connect to LaunchDarkly directly. In event forwarding mode, LD Relay can buffer and compress event payloads from multiple SDK instances |
| Air-gapped environments and snapshots | LD Relay can load flags or segments from an archive exported via the LaunchDarkly API. Available for Enterprise plans only |
| Reduce initialization latency | LD Relay acts as a local cache for initialization requests |
| Support PHP and serverless environments | LD Relay can service short-lived processes via proxy mode and populate persistent stores for daemon-mode clients |
| Syncing big segments to a persistent store | LD Relay can populate big segment stores with membership information for use with server-side SDKs |
Modes of operation
Proxy Mode: SDKs connect to LD Relay to receive flags and updates.
Daemon Mode: LD Relay syncs flags to a persistent store. SDKs retrieve flags as needed directly from the store and do not establish their own streaming connection
Daemon Mode is used in environments where the SDK can not establish a long-lived connection to LaunchDarkly. This is common in serverless environments where the function is terminated after a certain amount of time or PHP.
Additional features
Event forwarding: LD Relay buffers, compresses, and forwards events from the SDKs to LaunchDarkly
Big Segment Syncing: LD Relay syncs big segment data to a persistent store