Authentication

The Val Town APIs accept Bearer Token authentication for full access to your Val Town account. You can use the schemes below to give more scoped access to run specific vals.

Val Town Authentication

Keep your Val Town API token extremely guarded because it conveys access to your entire account and all of its environment variables. Never expose this token on the client.

Val Town’s API uses Bearer Authentication, which means you pass an HTTP Header Authorization: Bearer <token>.

If you don’t pass an authentication token, your code will be run as an anonymous user and only have access to public vals. For example, unauthenticated access to a private val will fail:

import { fetch } from "https://esm.town/v/std/fetch";

export const privateAPIUnauthenticated = (
  await fetch("https://api.val.town/v1/run/stevekrouse.example3")
).status;

Authenticated use will have read access to the authenticated user’s private vals and environment variables, write access to the authenticated user’s vals, and the ability to send the authenticated user emails via std/email.

import { fetchJSON } from "https://esm.town/v/stevekrouse/fetchJSON";

export const privateAPIAuthenticated = fetchJSON(
  "https://api.val.town/v1/run/stevekrouse.example3",
  {
    method: "GET",
    headers: { Authorization: "Bearer " + Deno.env.get("valtown") },
  }
);

You can access your Val Town API tokens here.

If you want to experiment with calling the Val Town API from within Val Town (as is shown above), you should copy-and-paste one of your Val Town API tokens into your environment variables.

Custom Authentication

You can roll arbitrary authentication schemes in user space. For example, I find it useful to simply supply a custom auth header from my Clerk webhooks that I check like a password against a value I store in my environment variables:

import { discordWebhook } from "https://esm.town/v/stevekrouse/discordWebhook";

// # New Val Town User (on Clerk) -> Val Town Discord notification
// Translates one kind of webhook (Clerk) into another (Discord)
export async function handleDiscordNewUser(req: express.Request, res) {
  // check custom auth secret sent from clerk
  if (req.get("auth") !== process.env.clerkNonSensitive)
    return res.end("Unauthorized");
  await discordWebhook({
    url: Deno.env.get("discordUserEvents"),
    content:
      req.body.data.email_addresses[0].email_address +
      " " +
      req.body.data.profile_image_url,
  });
  res.end("Success");
}

I call this value clerkNonSensitive because this value doesn’t protect any data. It merely makes it impossible for anyone to trigger this public API endpoint without the password. The worst that could happen if this password leaks is that our team temporarily gets spam discord messages. Then I could just change the password to a new value. For more sensitive use-cases, you’ll want to sign & possibly encrypt the conveyed data using standard authentication methods.

Hiding Code

You can hide the code of a public API by wrapping a private Val in a public val. Below I show hiddenAPI which you can see and call via API, but you notice that it calls @stevekrouse.hiddenAPIInternal which is private and can’t be inspected.

import { hiddenAPIInternal } from "https://esm.town/v/stevekrouse/hiddenAPIInternal";

export let hiddenAPI = (...args) => hiddenAPIInternal(...args);