Add Custom Auth SSR component

[vitorfigmgs]

Related PR

This PR is designed to work with the custom Auth UI feature introduced in OpenAuth:

• OpenAuth custom UI

• Usage Example The example will be added in an separate PR

---

Overview

This PR introduces the sst.aws.CustomAuth component to support fully customizable Auth UIs using vite powerered modern frontend UI libraries like React .

It allows developers to build their own authentication screens using @openauthjs/vite, deploy the compiled server to AWS Lambda, and run it locally with full HMR alongside their SST app.

Usage

Configure the component in your sst.config.ts by pointing it to your auth package directory.

Note: You currently must specify the dev.url manually, as SST cannot auto-detect the dev host yet.

export const auth = new sst.aws.CustomAuth("MyAuth", {
  path: "packages/auth",
  dev: {
    url: "http://localhost:5174" // Always remember to set this for local dev
  },
});

// Link it to your frontend or API
const web = new sst.aws.Nextjs("MyWeb", {
  link: [auth]
});