Adding Bluesky custom domain support to a Fresh app

If you've been a web developer, you probably know about the .well-known standard, it's where you store things like:

• ACME challege information if you are using the HTTP challenge for Let's Encrypt
• Apple Pay metadata
• Social network node information
• WebFinger responses for Mastodon user discovery
• Metadata for enrolment in Apple's mobile device management software

However, when you set up a custom username / domain name in Bluesky, you're supposed to set up a DNS TXT record pointing to your userid. But they do support fetching this information over HTTPS.

When I found about about this initially, I thought it would go in /.well-known/atproto or something to match the DNS record _atproto.friendshipcastle.zip. This would also prevent abuse and make it easier for operators of shared domains to prevent people from using their identity in social media, which could end in one of a thousand very bad things.

Nope.

Turns out you're supposed to put it in this very memorable path: /xrpc/com.atproto.identity.resolveHandle, and then you return a JSON document that looks like this:

{
    "did":"did:plc:g2ag3sguurbal7k6irnujf64"
}

This is how this guy became S3, all of S3. That seems totally brand-friendly.

When I implemented Bluesky support for my new domain friendshipcastle.zip, I decided to do it over HTTPS for logistical reasons involving spacebar heating and my DNS setup being complicated.

Here's how you do it with Fresh:

Create a file called routes/xrpc/com.atproto.identity.resolveHandle.ts and copy these contents into it:

import { HandlerContext } from "$fresh/server.ts";

const myDID = "did:plc:g2ag3sguurbal7k6irnujf64";

export const handler = async (
  req: Request,
  _ctx: HandlerContext,
): Promise<Response> => {
  return new Response(JSON.stringify({ did: myDID }), {
    headers: {
      "Content-Type": "application/json",
    },
  });
};

Then deploy your app to production and follow the "change my handle" workflow so you can use your domain in the hellthread all you want. You can be bulge-noticer.phd or whatever your twisted heart desires.

If you want, you can follow me at @friendshipcastle.zip. I post irregularly there and I'm still trying to figure out my relationship with social media.