Echo: httpbin on Cloudflare Workers

Sep 13, 2022

As a developer you may have come across the site httpbin.org. The purpose of the website is to provide a simple request and response service. For example, issuing a simple HTTP GET request “echos” back the request as the response, using JSON as the format.

curl https://httpbin.org/get
{
  "args": {},
  "headers": {
    "Accept": "*/*",
    "Host": "httpbin.org",
    "User-Agent": "curl/7.79.1",
  },
  "origin": "127.0.0.1",
  "url": "https://httpbin.org/get"
}

You can often find usages of httpbin in the wild, and given it is a really simple app it is a great candidate for being built on Workers.

The API for our implementation on Workers will very much like the example above. Given a request, the Worker will echo back the contents of the request in JSON format. The name of the project will be echo.

wrangler.toml

name = "echo"
main = "src/index.ts"
compatibility_date = "2022-09-13"

routes = [
    { pattern = "echo.mirio.dev", custom_domain = true }
]

src/index.ts

export default {
  async fetch(
    request: Request,
    env: Env,
    ctx: ExecutionContext,
  ): Promise<Response> {
    const { url, method } = request;
    const headers = Object.fromEntries(request.headers);
    return Response.json({ headers, url, method });
  },
};

Deploy it using wrangler publish, and give it a try!

curl -s https://echo.mirio.dev | jq
{
  "headers": {
    "accept": "*/*",
    "accept-encoding": "gzip",
    "cf-connecting-ip": "[redacted]",
    "cf-ipcountry": "US",
    "cf-ray": "74a607da58e20889",
    "cf-visitor": "{\"scheme\":\"https\"}",
    "connection": "Keep-Alive",
    "host": "echo.mirio.dev",
    "user-agent": "curl/7.79.1",
    "x-forwarded-proto": "https",
    "x-real-ip": "[redacted]"
  },
  "url": "https://echo.mirio.dev/",
  "method": "GET"
}

That all it is. You now have yourself your very own httbin that supports all the HTTP verbs and deployed in over 200 cities around the globe. 🤯

You can browse the code and wrangler config in the holster repo on GitHub.