unified-jwks.js

const axios = require("axios");

exports.handler = async (event) => {
    const jwksUrls = [
        'https://foo.au.auth0.com/.well-known/jwks.json',
        'https://bar.au.auth0.com/.well-known/jwks.json',
        'https://baz.au.auth0.com/.well-known/jwks.json',
    ];

    const responses = await Promise.all(jwksUrls.map((url) => axios.get(url)));
    const keySets = responses.map(response => response.data.keys.filter(key => key.kid !== key.x5t));
    const keys = [].concat(...keySets);

    const response = {
        keys,
    };

    return response;
};