Cloudflare Worker version (#6)

Refactor/generalise API/DB interactions out of OIDC.

README.md

@@ -2,11 +2,54 @@
 
 ## Getting Started
 
-### Dependencies
+Two versions are available, a stand-alone binary (using Axum and Redis) and a
+Cloudflare Worker. They use the same code base and are selected at compile time
+(compiling for `wasm32` will make the Worker version).
+
+### Cloudflare Worker
+
+You will need [`wrangler`](https://github.com/cloudflare/wrangler).
+
+Then copy the configuration file template:
+```bash
+cp wrangler_example.toml wrangler.toml
+```
+
+Replacing the following fields:
+- `account_id`: your Cloudflare account ID;
+- `zone_id`: (Optional) DNS zone ID; and
+- `kv_namespaces`: a KV namespace ID (created with `wrangler kv:namespace create SIWE-OIDC`).
+
+At this point, you should be able to create/publish the worker:
+```
+wrangler publish
+```
+
+The IdP currently only supports having the **frontend under the same subdomain as
+the API**. Here is the configuration for Cloudflare Pages:
+- `Build command`: `cd js/ui && npm install && npm run build`;
+- `Build output directory`: `/static`; and
+- `Root directory`: `/`.
+And you will need to add some rules to do the routing between the Page and the
+Worker. Here are the rules for the Worker (the Page being used as the fallback
+on the subdomain):
+```
+siweoidc.example.com/s*
+siweoidc.example.com/u*
+siweoidc.example.com/r*
+siweoidc.example.com/a*
+siweoidc.example.com/t*
+siweoidc.example.com/j*
+siweoidc.example.com/.w*
+```
+
+### Stand-Alone Binary
+
+#### Dependencies
 
 Redis, or a Redis compatible database (e.g. MemoryDB in AWS), is required.
 
-### Starting the IdP
+#### Starting the IdP
 
 The Docker image is available at `ghcr.io/spruceid/siwe_oidc:0.1.0`. Here is an
 example usage:
@@ -35,9 +78,23 @@ For the core OIDC information, it is available under
 
 * Additional information, from native projects (e.g. ENS domains), to more
   traditional ones (e.g. email).
+* PKCE support (code challenge).
+* Browser session support for the Worker version.
 
 ## Development
 
+### Cloudflare Worker
+
+```bash
+wrangler dev
+```
+You can now use http://127.0.0.1:8787/.well-known/openid-configuration.
+
+> At the moment it's not possible to use it end-to-end with the frontend as they
+> need to share the same host (i.e. port), unless using a local load-balancer.
+
+### Stand Alone Binary
+
 A Docker Compose is available to test the IdP locally with Keycloak.
 
 1. You will first need to run: