Creating microservices with koa inspired by zeit/micro

• Easy. You just need to learn koa.
• Micro. The whole project is ~100 lines of code.
• Agile. Super easy deployment and containerization.
• Simple. Oriented for single purpose modules (function).
• Explicit. No middleware. Modules declare all dependencies.
• Bulit-in koa-bodyparse.

The following example sleep.js will wait before responding (without blocking!)

const sleep = require('then-sleep');

module.exports = async function ({ request, response }) {
  await sleep(500);
  response.status = 200;
  response.body = 'woot';
};

To run the microservice on port 3000, use the micro-koa command:

micro-koa sleep.js

To run the microservice on port 3000 and localhost instead of listening on every interface, use the micro-koa command:

micro-koa -H localhost sleep.js

Install the package (requires at least Node v4):

npm install --save micro-koa

And start using it in your package.json file:

"main": "index.js",
"scripts": {
  "start": "micro-koa"
}

Then write your index.js (see above for an example).

After that, you can make the server run by executing the following command:

npm start

micro(fn)

• This function is exposed as the default export.

• Use require('micro-koa').

• Returns a http.Server created by koa that uses the provided fn as the last middleware.

• The supplied function is run with await. It can be async!

• Example:

  const micro = require('micro-koa');
  const sleep = require('then-sleep');
  const srv = micro(async function ({ request, response }) {
    await sleep(500);
    response.status = 200;
    response.body = 'woot';
  });
  srv.listen(3000);

send(res, statusCode, data = null)

• Use require('micro-koa').send.

• statusCode is a Number with the HTTP error code, and must always be supplied.

• If data is supplied it is sent in the response. Different input types are processed appropriately, and Content-Type and Content-Length are automatically set.

  • Stream: data is piped as an octet-stream. Note: it is your responsibility to handle the error event in this case (usually, simply logging the error and aborting the response is enough).
  • Buffer: data is written as an octet-stream.
  • object: data is serialized as JSON.
  • string: data is written as-is.

• Example

  const { send } = require('micro-koa')
  module.exports = async function ({ request, response }) {
    send(response, 400, { error: 'Please use a valid email' });
  }

createError(code, msg, orig)

• Use require('micro-koa').createError.
• Creates an error object with a statusCode.
• Useful for easily throwing errors with HTTP status codes, which are interpreted by the built-in error handling.
• orig sets error.originalError which identifies the original error (if any).

You can use the micro-koa CLI for npm start:

{
  "name": "my-microservice",
  "dependencies": {
    "micro-koa": "x.y.z"
  },
  "main": "microservice.js",
  "scripts": {
    "start": "micro-koa -p 3000"
  }
}

Then simply run npm start!

This package couldn't exist without the awesome micro and koa packages!

MIT © C.T. Lin