External Schema Composition

⚠️

Only available for Federation projects.

External Schema Composition feature allows you to build and validate GraphQL Schema outside of Hive. When enabled, Hive will send necessary information over HTTP to your endpoint and expect a composition result in return.

To make this process easier, we’ve implemented the actual service that you need to deploy: either as a JavaScript library, or as a Docker image that can be deployed anywhere.

How does it work?

💡

Your deployed external composition service needs to be available publicly, to make it possible for Hive Cloud service to communicate with it. Don’t worry: we’ve implemented a security layer to make sure only Hive can communicate with your service.

Hive Cloud uses Cloudflare Worker to communicate with your service. This means that service’s address must contain a valid hostname (not an IP address), and the port must be standard.

Integration Guide

Deploy External Composition Service

You can use our one-click deployment to deploy your External Composition Service to Heroku:

We provide a prebuilt Docker image for running External Composition Service for Apollo Federation v2.

The pre-built image implements the best-practice to secure your endpoint, and uses the latest version of Apollo Federation v2.

Start by deciding on your encryption secret. This is needed in order to ensure you endpoint is secured and can be triggered only by Hive platform. Your secret can be any string you decide, and it will be used as private key to hash the requests to your composition service.

To run the container, you can use the following command:

docker run -p 3069:3069 -e SECRET="MY_SECRET_HERE" \
  ghcr.io/graphql-hive/composition-federation-2

You should make this service publicly available, and then configure it in Hive platform.

You can also build your own JavaScript/NodeJS server for the composition endpoint. The following example shows how to do that.

The following example shows how to implement an External Composition endpoint for Apollo Federation v2 in NodeJS.

npm i -D @graphql-hive/external-composition

pnpm add -D @graphql-hive/external-composition

yarn add --dev @graphql-hive/external-composition

bun add --dev @graphql-hive/external-composition

The @graphql-hive/external-composition library provides a thin compose function to bring auto-completion and type-safety to your IDE.

Simple Fastify server for External Composition

import fastify from 'fastify'
import { parse, printSchema } from 'graphql'
import { composeServices } from '@apollo/composition'
import { compose, signatureHeaderName, verifyRequest } from '@graphql-hive/external-composition'
 
const composeFederation = compose(services => {
  const result = composeServices(
    services.map(service => {
      return {
        typeDefs: parse(service.sdl),
        name: service.name,
        url: service.url
      }
    })
  )
 
  if (result.errors?.length) {
    return {
      type: 'failure',
      result: {
        errors: result.errors.map(error => ({
          message: error.message,
          source: typeof error.extensions?.code === 'string' ? 'composition' : 'graphql'
        }))
      }
    }
  } else {
    return {
      type: 'success',
      result: {
        supergraph: result.supergraphSdl,
        sdl: printSchema(result.schema.toGraphQLJSSchema())
      }
    }
  }
})
 
const server = fastify()
 
server.route({
  method: ['POST'],
  url: '/compose',
  handler(req, res) {
    const error = verifyRequest({
      // Stringified body, or raw body if you have access to it
      body: JSON.stringify(req.body),
      // Pass here the signature from `X-Hive-Signature-256` header
      signature: req.headers[signatureHeaderName],
      // Pass here the secret you configured in Hive
      secret: YOUR_SECRET_HERE
    })
 
    if (error) {
      // Failed to verify the request - send 500 and the error message back
      res.status(500).send(error)
    } else {
      const result = composeFederation(req.body)
      // Send the result back (as JSON)
      res.send(JSON.stringify(result))
    }
  }
})
 
await server.listen({
  port: 3000
})

You can also find here an example using NodeJS’s HTTP library.

To make sure your server is only receiving requests from Hive, you can use the secret provided in the configuration and verify the signature of the request.

Please contact us if you need to limit access by whitelisting an IP address.

The logic of verifying the signature is as follows:

Get the value of X-Hive-Signature-256 header.
Take the raw body of the request.
Use an HMAC hex digest (sha256) to compute the hash (body with the secret provided in the configuration).
Compare the result with the value of the X-Hive-Signature-256 header (use “constant-time” comparison).

A NodeJS example of the verification process:

import crypto from 'node:crypto'
 
const sigHashAlg = 'sha256'
 
function hash(secret: string, data: string) {
  return crypto.createHmac(sigHashAlg, secret).update(data, 'utf-8').digest('hex')
}
 
function verifyRequest(input) {
  const { body, signature, secret } = input
 
  if (!body) {
    return 'ERR_EMPTY_BODY'
  }
 
  const sig = Buffer.from(signature ?? '', 'utf8')
  const digest = Buffer.from(hash(secret, body), 'utf8')
 
  if (sig.length !== digest.length || !crypto.timingSafeEqual(digest, sig)) {
    return 'ERR_INVALID_SIGNATURE'
  }
 
  // signature is valid
}

Connect to Hive

Start by enabling the External Composition for your project. To do that, go to your Hive project page, and click the Settings tab. You’ll notice a “External Composition” section.

External Composition section in the project settings

Next, provide the URL of your deployed endpoint, and also set the secret you set for your service. Click Save.

If your service is available publicly and the secret matches, you should see a green checkmark next to the URL:

In case of a failure, you’ll see a red cross with the reason of the failure:

Now you should be able to use the External Composition feature in your project. Publish a GraphQL schema or perform a GraphQL schema check to validate your setup.

Protocol Specification

You can use the following as reference for the expected shape of the request and response payloads.

Your external composition service will have 60s to complete the composition process, otherwise Hive server will result in a timeout.

Request

Hive will dispatch your HTTP service using POST method, with the following headers:

content-type: application/json
x-hive-signature-256 will be set the to the signature of the request body once encrypted with the secret you provided in the configuration.

The request body will contain the following information:

type SchemaService = {
  sdl: String!
  name: String!
  url: String
}
 
type RequestBody = Array<SchemaService>

Example request:

[
  {
    "sdl": "type Query { users: [String] }",
    "name": "users",
    "url": "https://api.com/users"
  },
  {
    "sdl": "extend type Query { comments: [String] }",
    "name": "comments",
    "url": "https://api.com/comments"
  }
]

Response

Hive will expect your HTTP service to respond with 200 status code and the following headers:

content-type: application/json

The reponse payload should match the following type:

type CompositionResult = CompositionSuccess | CompositionFailure
 
type CompositionSuccess = {
  type: 'success'
  result: {
    supergraph: string
    sdl: string
  }
}
 
type CompositionFailure = {
  type: 'failure'
  result: {
    errors: Array<{
      message: string
      source: 'graphql' | 'composition'
    }>
  }
}

Example response:

{
  "type": "failure",
  "result": {
    "errors": [
      {
        "message": "Type \"Query\" was defined more than once.",
        "source": "graphql"
      }
    ]
  }
}

In the source you are expected to return graphql if the error is related to the schema itself, or composition if the error is related to the composition process with other schemas.

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