:::callout{intent="note"} **How-to guide** · Assumes you have completed the [ElevenAPI quickstart](/guides/changelog-eleven-api-quickstart) and have a Supabase account. ::: ## Introduction In this guide you will learn how to build an edge API to generate, stream, store, and cache speech using Supabase Edge Functions, Supabase Storage, and ElevenLabs. https://www.youtube-nocookie.com/embed/4Roog4PAmZ8?rel=0 ## Requirements - An ElevenLabs account with an [API key](https://elevenlabs.io/app/settings/api-keys). - A [Supabase](https://supabase.com/) account (you can sign up for a free account via [database.new](https://database.new/)). - The [Supabase CLI](https://supabase.com/docs/guides/local-development) installed on your machine. - The [Deno runtime](https://docs.deno.com/runtime/getting_started/installation/) installed on your machine and optionally [setup in your facourite IDE](https://docs.deno.com/runtime/getting_started/setup_your_environment). ## Setup ### Create a Supabase project locally After installing the [Supabase CLI](https://supabase.com/docs/guides/local-development), run the following command to create a new Supabase project locally: ```bash supabase init ``` ### Configure the storage bucket You can configure the Supabase CLI to automatically generate a storage bucket by adding this configuration in the `config.toml` file: ```toml title="./supabase/config.toml" [storage.buckets.audio] public = false file_size_limit = "50MiB" allowed_mime_types = ["audio/mp3"] objects_path = "./audio" ``` :::callout{intent="note"} Upon running `supabase start` this will create a new storage bucket in your local Supabase project. Should you want to push this to your hosted Supabase project, you can run `supabase seed buckets --linked`. ::: ### Configure background tasks for Supabase Edge Functions To use background tasks in Supabase Edge Functions when developing locally, you need to add the following configuration in the `config.toml` file: ```toml title="./supabase/config.toml" [edge_runtime] policy = "per_worker" ``` :::callout{intent="note"} When running with `per_worker` policy, Function won’t auto-reload on edits. You will need to manually restart it by running `supabase functions serve`. ::: ### Create a Supabase Edge Function for Speech generation Create a new Edge Function by running the following command: ```bash supabase functions new text-to-speech ``` If you’re using VS Code or Cursor, select `y` when the CLI prompts “Generate VS Code settings for Deno? \[y/N]”! ### Set up the environment variables Within the `supabase/functions` directory, create a new `.env` file and add the following variables: ```title="supabase/functions/.env" # Find / create an API key at https://elevenlabs.io/app/settings/api-keys ELEVENLABS_API_KEY=your_api_key ``` ### Dependencies The project uses a couple of dependencies: - The [@supabase/supabase-js](https://supabase.com/docs/reference/javascript) library to interact with the Supabase database. - The ElevenLabs [JavaScript SDK](/guides/changelog-eleven-api-quickstart) to interact with the text-to-speech API. - The open-source [object-hash](https://www.npmjs.com/package/object-hash) to generate a hash from the request parameters. Since Supabase Edge Function uses the [Deno runtime](https://deno.land/), you don’t need to install the dependencies, rather you can [import](https://docs.deno.com/examples/npm/) them via the `npm:` prefix. ## Code the Supabase Edge Function In your newly created `supabase/functions/text-to-speech/index.ts` file, add the following code: ```typescript title="supabase/functions/text-to-speech/index.ts" // Setup type definitions for built-in Supabase Runtime APIs import "jsr:@supabase/functions-js/edge-runtime.d.ts"; import { createClient } from "jsr:@supabase/supabase-js@2"; import { ElevenLabsClient } from "npm:elevenlabs"; import * as hash from "npm:object-hash"; const supabase = createClient( Deno.env.get("SUPABASE_URL")!, Deno.env.get("SUPABASE_SERVICE_ROLE_KEY")! ); const elevenlabs = new ElevenLabsClient({ apiKey: Deno.env.get("ELEVENLABS_API_KEY"), }); // Upload audio to Supabase Storage in a background task async function uploadAudioToStorage(stream: ReadableStream, requestHash: string) { const { data, error } = await supabase.storage .from("audio") .upload(`${requestHash}.mp3`, stream, { contentType: "audio/mp3", }); console.log("Storage upload result", { data, error }); } Deno.serve(async (req) => { // To secure your function for production, you can for example validate the request origin, // or append a user access token and validate it with Supabase Auth. console.log("Request origin", req.headers.get("host")); const url = new URL(req.url); const params = new URLSearchParams(url.search); const text = params.get("text"); const voiceId = params.get("voiceId") ?? "JBFqnCBsd6RMkjVDRZzb"; const requestHash = hash.MD5({ text, voiceId }); console.log("Request hash", requestHash); // Check storage for existing audio file const { data } = await supabase.storage.from("audio").createSignedUrl(`${requestHash}.mp3`, 60); if (data) { console.log("Audio file found in storage", data); const storageRes = await fetch(data.signedUrl); if (storageRes.ok) return storageRes; } if (!text) { return new Response(JSON.stringify({ error: "Text parameter is required" }), { status: 400, headers: { "Content-Type": "application/json" }, }); } try { console.log("ElevenLabs API call"); const response = await elevenlabs.textToSpeech.stream(voiceId, { output_format: "mp3_44100_128", model_id: "eleven_multilingual_v2", text, }); const stream = new ReadableStream({ async start(controller) { for await (const chunk of response) { controller.enqueue(chunk); } controller.close(); }, }); // Branch stream to Supabase Storage const [browserStream, storageStream] = stream.tee(); // Upload to Supabase Storage in the background EdgeRuntime.waitUntil(uploadAudioToStorage(storageStream, requestHash)); // Return the streaming response immediately return new Response(browserStream, { headers: { "Content-Type": "audio/mpeg", }, }); } catch (error) { console.log("error", { error }); return new Response(JSON.stringify({ error: error.message }), { status: 500, headers: { "Content-Type": "application/json" }, }); } }); ``` ### Code deep dive There’s a couple of things worth noting about the code. Let’s step through it step by step. ::::steps :::step{title="Handle the incoming request"} To handle the incoming request, use the `Deno.serve` handler. In the demo we don’t validate the request origin, but you can for example validate the request origin, or append a user access token and validate it with [Supabase Auth](https://supabase.com/docs/guides/functions/auth). From the incoming request, the function extracts the `text` and `voiceId` parameters. The `voiceId` parameter is optional and defaults to the ElevenLabs ID for the “Allison” voice. Using the `object-hash` library, the function generates a hash from the request parameters. This hash is used to check for existing audio files in Supabase Storage. ```typescript Deno.serve(async (req) => { // To secure your function for production, you can for example validate the request origin, // or append a user access token and validate it with Supabase Auth. console.log("Request origin", req.headers.get("host")); const url = new URL(req.url); const params = new URLSearchParams(url.search); const text = params.get("text"); const voiceId = params.get("voiceId") ?? "JBFqnCBsd6RMkjVDRZzb"; const requestHash = hash.MD5({ text, voiceId }); console.log("Request hash", requestHash); // ... }) ``` ::: :::step{title="Check for existing audio file in Supabase Storage"} Supabase Storage comes with a [smart CDN built-in](https://supabase.com/docs/guides/storage/cdn/smart-cdn) allowing you to easily cache and serve your files. Here, the function checks for an existing audio file in Supabase Storage. If the file exists, the function returns the file from Supabase Storage. ```typescript const { data } = await supabase .storage .from("audio") .createSignedUrl(`${requestHash}.mp3`, 60); if (data) { console.log("Audio file found in storage", data); const storageRes = await fetch(data.signedUrl); if (storageRes.ok) return storageRes; } ``` ::: :::step{title="Generate Speech as a stream and split into two branches"} Using the streaming capabilities of the ElevenLabs API, the function generates a stream. The benefit here is that even for larger text, you can start streaming the audio back to your user immediately, and then upload the stream to Supabase Storage in the background. This allows for the best possible user experience, making even large text blocks feel magically quick. The magic here happens on line 17, where the `stream.tee()` method branches the readablestream into two branches: one for the browser and one for Supabase Storage. ```typescript try { const response = await elevenlabs.textToSpeech.stream(voiceId, { output_format: "mp3_44100_128", model_id: "eleven_multilingual_v2", text, }); const stream = new ReadableStream({ async start(controller) { for await (const chunk of response) { controller.enqueue(chunk); } controller.close(); }, }); // Branch stream to Supabase Storage const [browserStream, storageStream] = stream.tee(); // Upload to Supabase Storage in the background EdgeRuntime.waitUntil(uploadAudioToStorage(storageStream, requestHash)); // Return the streaming response immediately return new Response(browserStream, { headers: { "Content-Type": "audio/mpeg", }, }); } catch (error) { console.log("error", { error }); return new Response(JSON.stringify({ error: error.message }), { status: 500, headers: { "Content-Type": "application/json" }, }); } ``` ::: :::step{title="Upload the audio stream to Supabase Storage in the background"} The `EdgeRuntime.waitUntil` method on line 20 in the previous step is used to upload the audio stream to Supabase Storage in the background using the `uploadAudioToStorage` function. This allows the function to return the streaming response immediately to the browser, while the audio is being uploaded to Supabase Storage. Once the storage object has been created, the next time your users makes a request with the same parameters, the function will return the audio file from the Supabase Storage CDN. ```typescript // Upload audio to Supabase Storage in a background task async function uploadAudioToStorage( stream: ReadableStream, requestHash: string, ) { const { data, error } = await supabase.storage .from("audio") .upload(`${requestHash}.mp3`, stream, { contentType: "audio/mp3", }); console.log("Storage upload result", { data, error }); } ``` ::: :::: ## Run locally To run the function locally, run the following commands: ```bash supabase start ``` Once the local Supabase stack is up and running, run the following command to start the function and observe the logs: ```bash supabase functions serve ``` ### Try it out Navigate to `http://127.0.0.1:54321/functions/v1/text-to-speech?text=hello%20world` to hear the function in action. Afterwards, navigate to `http://127.0.0.1:54323/project/default/storage/buckets/audio` to see the audio file in your local Supabase Storage bucket. ## Deploy to Supabase If you haven’t already, create a new Supabase account at [database.new](https://database.new/) and link the local project to your Supabase account: ```bash supabase link ``` Once done, run the following command to deploy the function: ```bash supabase functions deploy ``` ### Set the function secrets Now that you have all your secrets set locally, you can run the following command to set the secrets in your Supabase project: ```bash supabase secrets set --env-file supabase/functions/.env ``` ## Test the function The function is designed in a way that it can be used directly as a source for an `