HTTP endpoints

Custom HTTP endpoints let an Effront application return JSON alongside its rendered Pages, using the same application services. The example adds GET /api/greeting to the application from the services guide and applies a shared response header to the Page and API.

Define a JSON endpoint

Create src/http.ts:

import { Effect } from "effect";
import { HttpRouter, HttpServerResponse } from "effect/unstable/http";
import { Greeting } from "./greeting";

export const GreetingApi = HttpRouter.use(
  Effect.fn(function* (router) {
    const greeting = yield* Greeting;
    yield* router.add(
      "GET",
      "/api/greeting",
      Effect.map(greeting.message("Ada"), (message) => HttpServerResponse.jsonUnsafe({ message })),
    );
  }),
);

Choose a path that does not overlap Page or Server Function URLs, and leave /_effront reserved.

Register the route and its service

In src/entry.effront.tsx, add Layer to the effect import and import GreetingApi.

// src/entry.effront.tsx: replace the effect import.
import { Effect, Layer } from "effect";
// Add to the imports.
import { GreetingApi } from "./http";

// Replace the default export.
const ApplicationLayer = GreetingApi.pipe(Layer.provideMerge(Greeting.layer));

export default EFFRONT.make({ routes, layer: ApplicationLayer });

Layer.provideMerge supplies Greeting to the route registration and retains it for the Page. Open /api/greeting. Expect status 200, content type application/json, and:

{ "message": "Hello, Ada." }

The existing / Page still displays the greeting.

Keep resources request-local

The application Layer is built for each request, including custom HTTP requests. Keep connections and other scoped resources within that request, whose scope lasts through response-body completion, failure, or cancellation.

Add a shared response header

Create src/application-layer.ts:

import { Effect, Layer } from "effect";
import { HttpRouter, HttpServerResponse } from "effect/unstable/http";
import { Greeting } from "./greeting";
import { GreetingApi } from "./http";

const GlobalHeaders = HttpRouter.middleware(
  (httpEffect) =>
    Effect.map(httpEffect, HttpServerResponse.setHeader("x-content-type-options", "nosniff")),
  { global: true },
);

export const ApplicationLayer = Layer.mergeAll(GreetingApi, GlobalHeaders).pipe(
  Layer.provideMerge(Greeting.layer),
);

In src/entry.effront.tsx, import the shared Layer and remove the local definition and unused imports:

// src/entry.effront.tsx: replace the effect import to remove Layer.
import { Effect } from "effect";
// Replace the GreetingApi import.
import { ApplicationLayer } from "./application-layer";

// Remove the local ApplicationLayer declaration.
export default EFFRONT.make({ routes, layer: ApplicationLayer });

Both / and /api/greeting now include x-content-type-options: nosniff.

global: true covers Pages, Server Functions, custom routes, and unmatched requests. Use scoped Middleware for a policy limited to one Routes group.