GrowthBook Proxy

GrowthBook is a modular Feature Flagging and Experimentation platform.

The GrowthBook Proxy server sits between your application and GrowthBook. It turbocharges your GrowthBook implementation by providing speed, scalability, security, and real-time feature rollouts.

Features:

• ⚡ Caching - Significantly faster feature lookups!
  • In-memory cache plus an optional distributed layer (Redis or MongoDB)
  • Automatic cache invalidation when features change in GrowthBook (using WebHooks)
• 📡 Streaming - Updates your application in real-time as features are changed or toggled (Javascript and React only)
• 🔒 Secure - Private-key authentication between GrowthBook and GrowthBook Proxy
• ↔️ Horizontally Scalable - Support millions of concurrent users

Coming soon:

• Server-side targeting and feature evaluation
• Realtime feature usage monitoring and alerting
• Additional support for edge deployments
• Streaming support for more SDKs

Installation

Install and run with Docker

docker pull growthbook/proxy:latest
docker run -d -p 3300:3300 \
  -e "GROWTHBOOK_API_HOST=https://growthbook-api.example.com" \
  -e "SECRET_API_KEY=key_abc123" \
  --name gbproxy growthbook/proxy

Then, simply point your GrowthBook SDKs to the GrowthBook Proxy instead of the GrowthBook API.

Self-hosted customers

You will also need to ensure that your self-hosted GrowthBook instance is configured to use the proxy server. This includes setting environment variables:

PROXY_ENABLED=1
PROXY_HOST_PUBLIC=https://proxy.example.com

## Optional; you may also use the GrowthBook UI to set this:
SECRET_API_KEY=something_secret

See GrowthBook's Proxy documentation for more information.

Cloud customers

For GrowthBook Cloud customers, use the GrowthBook app UI to create an API key in Settings -> API Keys. Additionally, you will need to set proxy's GROWTHBOOK_API_HOST environment variable to the cloud API server: https://api.growthbook.io.

Configuration

The GrowthBook Proxy supports a number of configuration options available via environment variables:

• GROWTHBOOK_API_HOST - Set this to the host and port of your GrowthBook API instance
• SECRET_API_KEY - Create a secret API key in GrowthBook by going to Settings -> API Keys
• NODE_ENV - Set to "production" to hide debug and informational log messages

Caching

By default, features are cached in memory in GrowthBook Proxy; you may provide your own cache service via Redis or Mongo. To fully utilize the GrowthBook Proxy, we highly recommend using Redis, which is a prerequisite for real-time updates when your proxy is horizontally scaled (as proxy instances are kept in-sync using Redis pub/sub).

• CACHE_ENGINE - One of: memory, redis, or mongo
• CACHE_CONNECTION_URL - The URL of your Redis or Mongo Database
• CACHE_STALE_TTL - Number of seconds until a cache entry is considered stale (default is 60 = 1 minute)
• CACHE_EXPIRES_TTL - Number of seconds until a cache entry is expired (default is 600 = 10 minutes)

Redis Cluster

Redis-specific options for cluster mode:
(Note that CACHE_CONNECTION_URL is ignored when using cluster mode)

• USE_CLUSTER - "true" or "1" to enable
• CLUSTER_ROOT_NODES - simple: comma-separated URLs to your cluster seed nodes
• CLUSTER_ROOT_NODES_JSON - advanced: JSON array of ClusterNode objects (ioredis)
• CLUSTER_OPTIONS_JSON - advanced: JSON object of ClusterOptions (ioredis)

MongoDB

Mongo-specific options:

• CACHE_DATABASE_NAME - Mongo database name (default is proxy)
• CACHE_COLLECTION_NAME - Mongo collection name (default is cache)

Horizontally scaling

For horizontally scaled GrowthBook Proxy clusters, we provide a basic mechanism for keeping your proxy instances in sync, which uses Redis Pub/Sub. To use this feature, you must use Redis as your cache engine and set the following option:

• PUBLISH_PAYLOAD_TO_CHANNEL - "true" or "1" to enable

SSL termination & HTTP2

Although we recommend terminating SSL using your load balancer, you can also configure the GrowthBook Proxy to handle SSL termination directly. It supports HTTP/2 by default, which is required for high performance streaming.

• USE_HTTP2 - "true" or "1" to enable
• HTTPS_CERT - The SSL certificate
• HTTPS_KEY - The SSL key

If the GrowthBook app your proxy is connecting to is using a self-signed certificate, you can disable certificate verification by setting NODE_TLS_REJECT_UNAUTHORIZED to "0".

Other common configuration options

• MAX_PAYLOAD_SIZE - The maximum size of a request body (default is "2mb")
• VERBOSE_DEBUGGING - "true" or "1" to enable verbose debugging
• ENABLE_EVENT_STREAM - "true" or "1" to enable streaming (on by default)
• EVENT_STREAM_MAX_DURATION_MS - The maximum duration of a SSE connection before the client is forced to reconnect (default is 60000 = 1 minute)
• EVENT_STREAM_PING_INTERVAL_MS - The interval between SSE "ping" messages sent to the client (default is 30000 = 30 seconds)