Some Deno Experiments

Deno-Justfile

PORT := "8000"
VERSION := "v2.6.0"
ARCH := "x86_64-unknown-linux-gnu"


install: # Deno binary for architecture
  curl -LO https://github.com/denoland/deno/releases/download/{{VERSION}}/deno-{{ARCH}}.zip
  unzip deno-{{ARCH}}.zip
  rm deno-{{ARCH}}.zip


serve:
  PORT=8000 \
  ./deno run \
    --allow-net \
    --allow-env \
    --allow-read=./welcome.txt \
    index.ts


get:
  curl 'http://localhost:8000/health'
  curl 'http://localhost:8000/hello?name=Karsten'


format:
  ./deno fmt index.ts
  ./deno lint index.ts


test:
  ./deno test --allow-read index_test.ts

index.ts

import { serve } from "https://deno.land/std@0.224.0/http/server.ts";
import { z } from "https://deno.land/x/zod@v3.23.8/mod.ts";

const PORT = Number(Deno.env.get("PORT") ?? "8000");
const TEMPLATE_PATH = Deno.env.get("TEMPLATE_PATH") ?? "./welcome.txt";

const Query = z.object({
  name: z.string().min(1).max(40).optional(),
});

async function loadWelcomeTemplate(): Promise<string> {
  return await Deno.readTextFile(TEMPLATE_PATH);
}

serve(
  async (req) => {
    const url = new URL(req.url);

    if (url.pathname === "/health") {
      return Response.json({ ok: true });
    }

    if (url.pathname === "/hello") {
      const parsed = Query.safeParse(Object.fromEntries(url.searchParams.entries()));
      if (!parsed.success) {
        return Response.json(
          { error: "invalid query", details: parsed.error.flatten() },
          { status: 400 },
        );
      }

      const name = parsed.data.name ?? "Welt";
      const template = await loadWelcomeTemplate();

      return Response.json({
        message: template.replaceAll("{{name}}", name),
        meta: {
          ts: new Date().toISOString(),
          ua: req.headers.get("user-agent"),
        },
      });
    }

    return new Response("Not found", { status: 404 });
  },
  { hostname: "0.0.0.0", port: PORT },
);