getAccessToken.js

import NodeCache from "node-cache"

const cache = new NodeCache()

/**
 * Retrieves an access_token from an OAuth Provider for building purposes,
 * using client_credentials (client secret) authorization type.
 */
export default async function getBuildToken(){
  try {
    const cachedAccessToken = cache.get("access_token")
    // Try returning the cached token
    if (cachedAccessToken) {
      return cachedAccessToken
    }
  
    /**
     * If no access token was present in the cache, fetch a new one
     * @see https://tools.ietf.org/html/rfc6749#section-4.4.3
     */
    const {access_token, expires_in} = await getServerSideAccessToken()
  
    // Update the cache with a time-to-live
    cache.set("access_token", access_token, expires_in)
  
    return access_token
  } catch (error) {
    console.error(error)
    throw new Error("Could not get access_token")
  }
}

async function getServerSideAccessToken() {
  const response = await fetch("https://oauth-provider.com/connect/token", {
    body: new URLSearchParams({
      client_id: process.env.CLIENT_ID,
      client_secret: process.env.CLIENT_SECRET,
      grant_type: "client_credentials",
      scope: "",
    }),
    headers: {
      "Content-Type": "application/x-www-form-urlencoded",
    },
    method: "post",
  })

  if (response.ok) {
    return response.json()
  }

  throw new Error("Failed getting an access_token")
}