Apollo Proxy for Remote Schema

graphql.ts

import { Handler } from 'aws-lambda'
import { ApolloServer } from 'apollo-server-lambda'
import { makeExecutableSchema, mergeSchemas } from '@graphql-tools/schema'
import { introspectSchema, wrapSchema } from '@graphql-tools/wrap'
import { AsyncExecutor } from '@graphql-tools/utils'
import { fetch } from 'cross-fetch'
import { printSchema, print } from 'graphql'

const { CONTENTFUL_CDA, CONTENTFUL_SPACE } = process.env

const executor: AsyncExecutor = async ({ document, variables }) => {
  const query = print(document)
  const fetchResult = await fetch(
    `https://graphql.contentful.com/content/v1/spaces/${CONTENTFUL_SPACE}`,
    {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        Authorization: `Bearer ${CONTENTFUL_CDA}`,
      },
      body: JSON.stringify({ query, variables }),
    },
  )
  return fetchResult.json()
}

const handler: Handler = async (event, context, callback) => {
  // console.log({ event })

  const role = event.requestContext?.authorizer?.role
  console.log({ requestContext: event.requestContext, role })

  const remoteSchema = wrapSchema({
    schema: await introspectSchema(executor),
    executor,
  })

  const localSchema = makeExecutableSchema({
    typeDefs: printSchema(remoteSchema) + localExtensions,
    resolvers: localResolvers,
  })

  const mergedSchema = mergeSchemas({
    schemas: [remoteSchema, localSchema],
  })

  const server = new ApolloServer({
    schema: mergedSchema,
    context: {
      role,
    },
    // introspection: true,
    // plugins: [ApolloServerPluginLandingPageGraphQLPlayground()],
  })

  const createServer = server.createHandler()
  return createServer(event, context, callback)
}

export const localExtensions = `
scalar _Any
scalar _FieldSet

type _Service {
  sdl: String
}

extend type Query {
  _service: _Service!
}

directive @external on FIELD_DEFINITION
directive @requires(fields: _FieldSet!) on FIELD_DEFINITION
directive @provides(fields: _FieldSet!) on FIELD_DEFINITION
directive @key(fields: _FieldSet!) repeatable on OBJECT | INTERFACE

# this is an optional directive discussed below
directive @extends on OBJECT | INTERFACE

extend type VideoPost {
  url: String @requires(fields: "restrictToRoles")
}`

const localResolvers = {
  VideoPost: {
    url: (parent: any, args: any, context: any, info: any) => {
      const isAllowed =
        !parent.restrictToRoles?.length || parent.restrictToRoles?.includes(context.role)
      console.log({ parent, args, context, info })
      return isAllowed ? parent.url : null
    },
  },
}

export { handler }