[!NOTE] As of October 2024, OpenAI now officially supports prompt caching in most models: https://openai.com/index/api-prompt-caching/. It is recommended that you use OpenAI's official implementation instead.

openai-caching-proxy-worker

Basic caching proxy for OpenAI API, deployable as a Cloudflare Worker.

This can help you reduce your OpenAI costs (and get faster results) by returning cached responses for repeated requests.

The proxy server supports specifying cache TTL on a per-request basis, so you could configure this based on your needs. For example, the text-davinci-003 model is 10x the cost of text-curie-001 so you could choose to cache results for longer for davinci.

Client compatibility:

• openai/openai-node: full compatibility, takes just a few lines of config to use
• openai/openai-python: partial compatibility, supports caching but no TTL options so you'll need a cache eviction policy
• alexrudall/ruby-openai: partial compatibility, supports caching but no TTL options so you'll need a cache eviction policy

It only caches POST requests that have a JSON request body, as these tend to be the slowest and are the only ones that cost money (for now).

Setup

Clone the repo and install dependencies.

You will need to sign up for two services (which both have free tiers):

• Cloudflare: Where our worker will be hosted.
• Upstash: We use Upstash's redis-over-HTTP service for storing cached OpenAI responses.

Finally, set up your redis secrets based on instructions in wrangler.toml.

Depending on your usage, you may try replacing Redis with Cloudflare KV instead which is eventually consistent but will likely provide better read latency. Check wrangler.toml for setup instructions.

Usage

Start the proxy server at http://localhost:8787 with:

yarn start

Then, in your separate project where you have your openai/openai-node configuration, pass in the new basePath so that it sends requests through your proxy rather than directly to OpenAI:

const { Configuration, OpenAIApi } = require("openai");

const configuration = new Configuration({
  apiKey: process.env.OPENAI_API_KEY,
+ // Point this to your local instance or Cloudflare deployment:
+ basePath: 'http://localhost:8787/proxy',
});
const openai = new OpenAIApi(configuration);

You can then try a few sample requests. The first will be proxied to OpenAI since a cached response isn't yet saved for it, but the second repeated/duplicate request will return the cached result instead.

const options = { model: 'text-ada-001', prompt: 'write a poem about computers' };

// This first request will be proxied as-is to OpenAI API, since a cached
// response does not yet exist for it:
const completion = await openai.createCompletion(options);
console.log('completion:', completion);

// This second request uses the same options, so it returns nearly instantly from
// local cache and does not make a request to OpenAI:
const completionCached = await openai.createCompletion(options);
console.log('completionCached:', completionCached);

Specifying a cache TTL

If you don't want to indefinitely cache results, or you don't have an eviction policy set up on your redis instance, you can specify a TTL in seconds using the X-Proxy-TTL header.

const configuration = new Configuration({
  ...
+ baseOptions: {
+   // In this example, we specify a cache TTL of 24 hours before it expires:
+   headers: { 'X-Proxy-TTL': 60 * 60 * 24 }
+ }
});

Refreshing the cache

If you need to force refresh the cache, you can use the header X-Proxy-Refresh. This will fetch a new response from OpenAI and cache this new response.

const configuration = new Configuration({
  ...
+ baseOptions: {
+   headers: { 'X-Proxy-Refresh': 'true' }
+ }
});

Example client usage

See /examples/ directory for a full example of how to call this proxy with your openai client.

This includes both Node.js, Python and Ruby client usage examples.