LaunchDarkly Relay Proxy

What is it?

The LaunchDarkly Relay Proxy establishes a connection to the LaunchDarkly streaming API, then proxies that stream connection to multiple clients.

The relay proxy lets a number of servers connect to a local stream instead of making a large number of outbound connections to stream.launchdarkly.com.

The relay proxy can be configured to proxy multiple environment streams, even across multiple projects.

Quick setup

1. Copy ld-relay.conf to /etc/ld-relay.conf, and edit to specify your port and LaunchDarkly API keys for each environment you wish to proxy.

2. If building from source, have go 1.6+ and godep installed, and run godep go build.

3. Run ld-relay.

4. Set stream to true in your application's LaunchDarkly SDK configuration. Set the streamUri parameter to the host and port of your relay proxy instance.

Configuration file format

You can configure LDR to proxy as many environments as you want, even across different projects. You can also configure LDR to send periodic heartbeats to connected clients. This can be useful if you are load balancing LDR instances behind a proxy that times out HTTP connections (e.g. Elastic Load Balancers).

Here's an example configuration file that synchronizes four environments across two different projects (called Spree and Shopnify), and sends heartbeats every 15 seconds:

    [main]
    streamUri = "https://stream.launchdarkly.com"
    baseUri = "https://app.launchdarkly.com"
    exitOnError = false
    heartbeatIntervalSecs = 15

    [environment "Spree Project Production"]
    apiKey = "SPREE_PROD_API_KEY"

    [environment "Spree Project Test"]
    apiKey = "SPREE_TEST_API_KEY"

    [environment "Shopnify Project Production"]
    apiKey = "SHOPNIFY_PROD_API_KEY"

    [environment "Shopnify Project Test"]
    apiKey = "SHOPNIFY_TEST_API_KEY"

Redis storage and daemon mode

You can configure LDR to persist feature flag settings in Redis. This provides durability in case of (e.g.) a temporary network partition that prevents LDR from communicating with LaunchDarkly's servers.

Optionally, you can configure our SDKs to communicate directly to the Redis store. If you go this route, there is no need to put a load balancer in front of LDR-- we call this daemon mode.

To set up LDR in this mode, provide a redis host and port, and supply a Redis key prefix for each environment in your configuration file:

    [redis]
    host = "localhost"
    port = 6379

    [main]
    ...

    [environment "Spree Project Production"]
    prefix = "ld:spree:production"
    apiKey = "SPREE_PROD_API_KEY"

    [environment "Spree Project Test"]
    prefix = "ld:spree:test"
    apiKey = "SPREE_TEST_API_KEY"

If you're not using a load balancer in front of LDR, you can configure your SDKs to connect to Redis directly by setting use_ldd mode to true in your SDK, and connecting to Redis with the same host and port in your SDK configuration.