Mostly complete Apollo Client 2.0 initialization code

apollo.js

export default async (services) => {

  // Links.

  const contextLink = new ApolloLink((operation, forward) => {
    operation.setContext(context => update(context, {
      headers: {
        $apply: (headers = {}) => {
          headers = {
            ...headers,
            'Cookie': '',
          };

          const sessionId = (
            overrideSessionId || getSessionId(services.store.getState())
          );

          if (sessionId) {
            headers = {
              ...headers,
              'Authorization': sessionId,
            };
          }

          return headers;
        },
      },
    }));

    return forward(operation);
  });

  const errorLink = new ErrorLink(({response}) => {
    if (errorCode(response) === 'SESSION_REQUIRED') {
      services.store.dispatch(Session.accountRequired());
      response.errors = null;
    }
  });

  const httpLink = enableApolloBatching
    ? new BatchHttpLink({uri: apiUri})
    : new HttpLink({uri: apiUri});

  const link = ApolloLink.from([contextLink, errorLink, httpLink]);

  // Cache.

  const fragmentMatcher = new IntrospectionFragmentMatcher({
    introspectionQueryResultData: schema.data,
  });

  const cache = services.cache = new InMemoryCache({
    fragmentMatcher,
    addTypename: true,
    dataIdFromObject: getId,
    customResolvers: {
      Query: {
        node: (_, {id}) => toIdValue(id),
      },
    },
  });

  // Persistence.

  const cacheKey = `${services.key}:apollo:2`;

  cache.persist = () => persistCache(cacheKey, cache);

  if (!purgeCache) {
    await restoreCache(cacheKey, cache);
  }

  // Client.

  services.client = new ApolloClient({link, cache});
};