gatsby-browser.jsx

import fetch from ‘isomorphic-fetch’;
import React from ‘react’;
import { ApolloProvider } from 'react-apollo';
import ApolloClient from 'apollo-boost';

// Wraps the entire Gatsby app with Apollo.
export const wrapRootElement = ({ element }) => {
    // Register a new Apollo client.
    const client = new ApolloClient({
        fetch,
        // Change this to your GraphQL endpoint.
        uri: 'http://example.com/graphql',
    });

    // Wrap the element.
    return <ApolloProvider client={client}>{element}</ApolloProvider>;
};