Shared code to run local apollo server next to firebase functions

config.js

const gql = require('graphql-tag');
const { makeExecutableSchema } = require('graphql-tools');

const books = [
  // ...
];

const typeDefs = gql`
  # ...
`;

const resolvers = {
  Query: {
    books: () => books,
  },
};

module.exports = {
  schema: makeExecutableSchema({
    typeDefs,
    resolvers,
  }),
  // Bonus function, to remove stack trace on production
  // https://www.apollographql.com/docs/apollo-server/features/errors
  formatError: (error) => {
    if (process.env.NODE_ENV === 'production') {
      delete error.extensions.exception;
    }
    return error;
  },
}

firebase-functions.js

const { ApolloServer } = require('apollo-server-cloud-functions');
const functions = require('firebase-functions');
const config = require('./lib/config');

const server = new ApolloServer(config);
const handler = server.createHandler({
  cors: {
    origin: true,
    credentials: true,
  },
});

exports.handler = functions.https.onRequest(handler);

local-server.js

const { ApolloServer } = require('apollo-server');
const config = require('./config');

const server = new ApolloServer(config);

// This `listen` method launches a web-server.  Existing apps
// can utilize middleware options, which we'll discuss later.
server.listen().then(({ url }) => {
  console.log(`🚀  Server ready at ${url}`);
});