javascript - 具有网关服务器作为服务的 Apollo 联邦

Question

问题摘要已在 Github 问题中进行了描述:

https://github.com/apollographql/apollo-server/issues/2794

---

简而言之，有没有一种方法可以实现 Apollo Federation，使网关本身拥有自己的模式？

联合 Apollo Server，其中网关本身有一个模式

@apollo/gateway@0.6.5@apollo/federation@0.6.2

预期行为

当我实例化我的 Apollo 网关服务器时，我希望我应该能够合并来自联合服务的模式，以及来自网关本身的模式。

实际行为

网关服务器无法挂载 /graphql 路由，因为它期望所有服务在挂载之前当前正在运行。

在运行时，以下错误会打印到控制台:

POST /graphql 404 11.251 ms - 147
Encountered error when loading gateway-app at http://localhost:8000/graphql: invalid json response body at http://localhost:8000/graphql reason: Unexpected token < in JSON at position 0
[DEBUG] Fri Jun 07 2019 12:11:07 GMT-0400 (Eastern Daylight Time) apollo-gateway: Configuration loaded for Gateway
[DEBUG] Fri Jun 07 2019 12:11:07 GMT-0400 (Eastern Daylight Time) apollo-gateway: Composing schema from service list:
  remove-svc
TypeError: schema.toConfig is not a function
    at Object.composeServices (/gateway-app/node_modules/@apollo/federation/dist/composition/compose.js:191:67)
    at Object.composeAndValidate (/gateway-app/node_modules/@apollo/federation/dist/composition/composeAndValidate.js:13:41)
    at ApolloGateway.createSchema (/gateway-app/node_modules/@apollo/gateway/dist/index.js:90:47)
    at ApolloGateway.<anonymous> (/gateway-app/node_modules/@apollo/gateway/dist/index.js:81:22)
    at Generator.next (<anonymous>)
    at fulfilled (/gateway-app/node_modules/@apollo/gateway/dist/index.js:4:58)
    at process._tickCallback (internal/process/next_tick.js:68:7)

源代码

const url = new URL(`redis://${REDIS_URL}:${REDIS_PORT}/${REDIS_DATABASE}`).toString()

const cache = new RedisCache({ url })

const context = ({ req }) => {
  if (!(req.user || req.headers.authorization === ROUTE_AUTH)) {
    throw new AuthenticationError('Not authenticated')
  }
  return { user: req.user, req: req }
}

try {
  const loadGateway = async () => {
    try {
      const { schema, executor } = await gateway.load()
      return { schema, executor }
    } catch (err) {
      console.error(err)
      return null
    }
  }

  const gateway = new ApolloGateway({
    debug: process.env.ENV !== 'prod',
    serviceList: [
      { name: 'gateway', url: `${GATEWAY_HOSTNAME}/graphql` },
      { name: 'remote-svc', url: `${REMOTE_SERVICE_HOSTNAME}/graphql` },
    ],
  })

  const { schema, executor } = loadGateway()
  const server = new ApolloServer({
    schema,
    executor,
    cache,
    dataSources,
    engine: { apiKey: ENGINE_API_KEY },
    tracing: true,
    context,
  })
  server.applyMiddleware({ app })
} catch (err) {
  console.error(err)
}

Answer 1

根据我的问题报告的原始错误，有两个错误。

1. Apollo 网关服务器不能也不应该是具有自己架构的联合服务(参见 Github Issue #2792 )。

来自 Apollo :

I'll jump to a conclusion here based on the naming of your service: are you trying to run the gateway at port 8000 and treat it as a federated service at the same time? If so, that's not going to work; the gateway has to resolve all schemas before it can compose the final schema.

1. GraphQL 核心依赖项的版本必须至少为 14.2.0(参见 Github Issue #2825)。

来自 GraphQL JS 变更日志:

toConfig is intended to help with schema transformation by minimizing the amount of code you need write and maintain, e.g. recreateType from graphql-tools.

When I worked on graphql-voyager I created my own intermidiate format just to do schema transformations.

Moreover, toConfig will prevent bugs that occur when a new field is added. For example, lexicographicSortSchema doesn't respect newly added assumeValid and allowedLegacyNames fields.

将架构从网关迁移到它自己的联合服务并将我的核心 GraphQL 依赖项更新到适当的版本后，我能够成功地实现网关/联合模式。