apollo-gateway-subscription/src/utils/schema.ts

Sidecar for subscriptions that work with Apollo Federation/Supergraphs

import { createHash } from "crypto";

import { makeExecutableSchema } from "graphql-tools";
import { gql } from "graphql-tag";
import { DocumentNode, printSchema } from "graphql";

export function getGatewayApolloConfig(key: string, graphRef: string) {
  return {
    key,
    graphRef,
    keyHash: createHash("sha512").update(key).digest("hex")
  };
}

export function makeSubscriptionSchema({
  gatewaySchema,
  typeDefs,
  resolvers
}: any) {
  if (!typeDefs || !resolvers) {
    throw new Error(
      "Both `typeDefs` and `resolvers` are required to make the executable subscriptions schema."
    );
  }

  const gatewayTypeDefs = gatewaySchema
    ? gql(printSchema(gatewaySchema))
    : undefined;

  return makeExecutableSchema({
    typeDefs: [
      ...((gatewayTypeDefs && [gatewayTypeDefs]) as DocumentNode[]),
      typeDefs
    ],
    resolvers
  });
}