index.js

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

  // This is a (sample) collection of books we'll be able to query
  // the GraphQL server for.  A more complete example might fetch
  // from an existing data source like a REST API or database.
  const books = [
    {
      title: 'Harry Potter and the Chamber of Secrets',
      author: 'J.K. Rowling',
    },
    {
      title: 'Jurassic Park',
      author: 'Michael Crichton',
    },
  ];

  // Type definitions define the "shape" of your data and specify
  // which ways the data can be fetched from the GraphQL server.
  const typeDefs = gql`
    # Comments in GraphQL are defined with the hash (#) symbol.

    # This "Book" type can be used in other type declarations.
    type Book {
      title: String
      author: String
    }

    # The "Query" type is the root of all GraphQL queries.
    # (A "Mutation" type will be covered later on.)
    type Query {
      books: [Book]
    }
  `;

  // Resolvers define the technique for fetching the types in the
  // schema.  We'll retrieve books from the "books" array above.
  const resolvers = {
    Query: {
      books: () => books,
    },
  };

  // In the most basic sense, the ApolloServer can be started
  // by passing type definitions (typeDefs) and the resolvers
  // responsible for fetching the data for those types.
  const server = new ApolloServer({ 
    typeDefs, 
    resolvers,
    engine: {
      apiKey: process.env.ENGINE_API_KEY
    } 
  });

  // 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}`);
  });