Integrations export their own ApolloServer

[evans]

This PR creates ApolloServer classes for the hapi, express, and cloudflare integrations. The constructor will continue to stay the same across all environments(ideally there would be a way to programmatically enforce this). The reasons to do this are the ApolloServer class in apollo-server brings the extra dependency on express, which does not work for serverless environments. The presumably more common path is going to be to use apollo-server-{variant}, so that should be equally as understandable/easy as the getting started experience. The arguments the context creation function will be set by the variant and be type safe, see #1110. The new typings should also solve #1140

The downside is that we won't be using the apollo-server package everywhere. I'm unconvinced this will be possible.

This PR stays backwards compatible with the dual import of apollo-server and apollo-server-express(below), however the documentation should be updated to reflect these changes.

The old way:

const express = require('express');
const { registerServer } = require('apollo-server-express');
const { ApolloServer, gql } = require('apollo-server');

const server = new ApolloServer({ typeDefs, resolvers });

const app = express();
registerServer({ server, app });

server.listen().then(({ url }) => {
  console.log(`🚀 Server ready at ${url}`);
});

The new way of importing would be as follows:

apollo-server

const { ApolloServer, gql } = require('apollo-server');
// There could be a possibility to import registerExpressServer, however I don't think we need it

const server = new ApolloServer({ typeDefs, resolvers });

server.listen().then(({ url }) => {
  console.log(`🚀 Server ready at ${url}`);
});

apollo-server-express

const express = require('express');
const { ApolloServer, gql, registerServer } = require('apollo-server-express');

const server = new ApolloServer({ typeDefs, resolvers });

const app = express();
registerServer({ server, app });

server.listen().then(({ url }) => {
  console.log(`🚀 Server ready at ${url}`);
});

apollo-server-hapi

const { registerServer, ApolloServer, gql } = require('apollo-server-hapi');

async function StartServer() {
  const server = new ApolloServer({ typeDefs, resolvers });

  await registerServer({
    server,
    //Hapi Server constructor options
    options: {
      host: 'localhost',
    },
  });

  server.listen().then(({ url }) => {
    console.log(`🚀  Server ready at ${url}`);
  });
}

StartServer().catch(error => console.log(error));

[evans]

Note that options to registerServer for different integrations include things like:

• cors
• body parser
• health-check
• uploads
• path

ApolloServer accepts anything that relates to the schema + engine reporting(the same across all envs), things like:

• typeDefs
• resolvers
• context(note that the arguments are integration specific/provided)
• directive
• mocks
• persistedQueries
• extensions

[unicodeveloper]

@evans I like this approach. Fewer imports for apollo-server variants. What's the ETA for getting this merged and tagged?

[glasser]

"provided". also it's a function, not a method.

Also I'm not sure that documenting something as simplifying something with a new method will age well? Maybe just be more explicit about what it does, like "This function is what lets you connect your ApolloServer to your web framework. Use it instead of the listen method when you want to customize your app's web behavior."
or something

[glasser]

"integration-specific" with hyphen. Maybe document that this is equivalent to the arguments to the cors or hapi-cors packages, with links?

[glasser]

Link to body-parser?

[glasser]

Why does this function take a request argument rather than an options argument like the one it calls? Also what is the point of this function and why does it have a different name than graphQLServerOptions?

[glasser]

shouldn't this be request rather than req?

[glasser]

yeah i don't get this. is it a typing thing?

[glasser]

Doesn't a-s-e need to export gql now too?

[evans]

It does now https://github.com/apollographql/apollo-server/pull/1161/files#diff-cbf9fd9271eaacde30d8349212808beeR2 🎉