Generating OpenAI GPT3 completions

OpenAI provides a completions API that allows you to use their generative GPT models in your own applications.

OpenAI's API is intended to be used from the server-side. Supabase offers Edge Functions to make it easy to interact with third party APIs like OpenAI.

Setup Supabase project#

If you haven't already, install the Supabase CLI and initialize your project:

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supabase init

Create edge function#

Scaffold a new edge function called openai by running:

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supabase functions new openai

A new edge function will now exist under ./supabase/functions/openai/index.ts.

We'll design the function to take your user's query (via POST request) and forward it to OpenAI's API.

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import OpenAI from 'https://deno.land/x/openai@v4.24.0/mod.ts'
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Deno.serve(async (req) => {
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  const { query } = await req.json()
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  const apiKey = Deno.env.get('OPENAI_API_KEY')
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  const openai = new OpenAI({
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    apiKey: apiKey,
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  })
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  // Documentation here: https://github.com/openai/openai-node
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  const chatCompletion = await openai.chat.completions.create({
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    messages: [{ role: 'user', content: query }],
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    // Choose model from here: https://platform.openai.com/docs/models
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    model: 'gpt-3.5-turbo',
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    stream: false,
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  })
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  const reply = chatCompletion.choices[0].message.content
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  return new Response(reply, {
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    headers: { 'Content-Type': 'text/plain' },
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  })
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})

Note that we are setting stream to false which will wait until the entire response is complete before returning. If you wish to stream GPT's response word-by-word back to your client, set stream to true.

Create OpenAI key#

You may have noticed we were passing OPENAI_API_KEY in the Authorization header to OpenAI. To generate this key, go to https://platform.openai.com/account/api-keys and create a new secret key.

After getting the key, copy it into a new file called .env.local in your ./supabase folder:

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OPENAI_API_KEY=your-key-here

Run locally#

Serve the edge function locally by running:

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supabase functions serve --env-file ./supabase/.env.local --no-verify-jwt

Notice how we are passing in the .env.local file.

Use cURL or Postman to make a POST request to http://localhost:54321/functions/v1/openai.

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curl -i --location --request POST http://localhost:54321/functions/v1/openai \
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  --header 'Content-Type: application/json' \
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  --data '{"query":"What is Supabase?"}'

You should see a GPT response come back from OpenAI!

Deploy#

Deploy your function to the cloud by running:

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supabase functions deploy --no-verify-jwt openai
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supabase secrets set --env-file ./supabase/.env.local

Go deeper#

If you're interesting in learning how to use this to build your own ChatGPT, read the blog post and check out the video: