Custom Proxy for Statsig API

How the custom proxy works

Instead of sending API requests directly to Statsig, you can set up your own environment that proxies requests from your custom domain name to Statsig. This reduces the likelihood that tracking blockers intercept your APIs, and allows you to capture more data.

These instructions cover a few common service providers. Many other proxy configurations are possible.

Approaches

AWS CloudFront

Prerequisites

• Write access to your DNS settings.
• Write access on your AWS CloudFront and Lambda console.
• Access to a SSL certificate for your custom domain.

Setup

• Click on Create distribution.

• In the Origin section,

  • Set the Origin Domain to api.statsig.com.
  • Set the Protocol to HTTPS only.

  

• In the Default cache behavior section,

  • Set Viewer protocol policy to Redirect HTTP to HTTPS.
  • Set Allowed HTTP methods to GET, HEAD, OPTIONS, PUT, POST, PATCH, DELETE.
  • In the Cache Key and origin requests subsection, allow all headers and parameters to be forwarded to the Origin, and allow CORS requests for the Origin.

  

• In Function associations section,

  • Add a Lambda@Edge function to Origin request to rewrite the Host header to api.statsig.com and rewrite custom endpoint paths to Statsig endpoints. Refer to the AWS tutorial on creating a Lambda@Edge function.

  

You can use the following javascript code snippet in your Lambda@Edge function. This example rewrites a custom endpoint /v1/my-product-data to the Statsig endpoint /v1/log_event:

export const handler = async (event, context, callback) => {
  const request = event.Records[0].cf.request;
  request.headers.host[0].value = "api.statsig.com";
  
  // Rewrite custom endpoint to Statsig endpoint
  // Replace 'my-product-data' with your custom endpoint name
  if (request.uri.includes('/v1/my-product-data')) {
    request.uri = request.uri.replace('/v1/my-product-data', '/v1/log_event');
  }
  
  return callback(null, request);
};

• In Settings,

  • Add an Alternate domain name (CNAME) to be your preferred domain name to use for the custom proxy, e.g. statsig.example.com.
  • Add a Custom SSL certificate. Follow the AWS guide for Alternate domain name to add a SSL certificate.
  • Click on Create distribution.

• You get a Distribution domain name (e.g. d111111abcdef8.cloudfront.net) once AWS provisions it.

In your DNS settings (depending on your DNS provider),

• Add a CNAME record in your custom DNS record:

  • Host name: statsig.example.com
  • Type: CNAME
  • Data: d111111abcdef8.cloudfront.net (The Distribution domain name from AWS)
• Your proxy is now set up. Go to Using Your Proxy for instructions on how to configure your Statsig SDK.

Cloudflare Worker

Prerequisites

Setup

After you log into Cloudflare, follow these steps:

1. Navigate to "Workers & Pages > Overview" in the left rail to create a new worker.

   

3. Name your new worker and click "Deploy".

   

4. Once deployed, click "Edit Code".

   

5. Copy and paste the following snippet into the worker.js file, then hit "Deploy". This example rewrites a custom endpoint /v1/my-product-data to the Statsig endpoint /v1/log_event:

   javascript

   Copy

   export default {
     async fetch(request, _env, _ctx) {
       const url = new URL(request.url);
       
       // Rewrite custom endpoint to Statsig endpoint
       // Replace 'my-product-data' with your custom endpoint name
       let pathname = url.pathname;
       if (pathname.includes('/v1/my-product-data')) {
         pathname = pathname.replace('/v1/my-product-data', '/v1/log_event');
       }
   
       const original = new Request(request);
       original.headers.delete("cookie");
       return fetch(
         `https://statsigapi.net$\{pathname\}${url.search}`,
         original
       );
     },
   };
   

   

6. Your worker is now deployed. Go to Using Your Proxy for instructions on how to configure your Statsig SDK.

Using your proxy

The following example shows initializing with a proxy in JavaScript:

Statsig.initialize(mySdkKey, myUser, {
  networkConfig: {
    api: "https://my-statsig-proxy.com/v1",
  },
});

JavaScript failover example

If you want JavaScript clients to use your proxy as the primary endpoint and a second endpoint as failover, configure fallback URLs per endpoint:

Statsig.initialize(mySdkKey, myUser, {
  networkConfig: {
    api: "https://my-statsig-proxy.com/v1",
    initializeFallbackUrls: [
      "https://my-proxy-cache.com/v1/initialize",
    ],
    logEventFallbackUrls: [
      "https://my-proxy-cache.com/v1/rgstr",
    ],
  },
});

Configuring custom endpoints

If you configured your proxy to use custom endpoint names (recommended to avoid tracking blockers), configure the SDK to use those custom endpoints. The SDK appends the endpoint path to your base URL.

For example, if your proxy rewrites /v1/my-product-data to /v1/log_event, configure:

Statsig.initialize(mySdkKey, myUser, {
  networkConfig: {
    api: "https://my-statsig-proxy.com/v1",
    logEventUrl: "https://my-statsig-proxy.com/v1/my-product-data",
  },
});

Go to your SDK's documentation for the configuration options available for customizing endpoint URLs.