Middleware for Express, Koa and Hapi

[IvanGoncharov]

It would be great to plug playground into your server without writing too much boilerplate code.
Middleware solves this problem and enables you to write code like this:

import express from 'express';
import { express as middleware } from 'graphql-playground/middleware';

const app = express();

app.use('/playground', middleware({ endpointUrl: '/graphql' }));

app.listen(3000);

Here is how it is implemented in Voyager:
graphql-kit/graphql-voyager@ba35ed1...96009e8
Almost all the code can be reused for playground with minor changes :)

[pradel]

Done 😄 https://github.com/graphcool/graphql-playground/tree/playground-app#middleware

[schickling]

This needs to be revisited before release.