killjoy2013 / graphql.net-in-apollo-federation

This is a proof of concept repo trying to use a Graphql.net 4 webapi as a subgraph inside an Apollo Server Graphql Federation

Modules are;

federation-gateway (http://localhost:3000/graphql) : Apollo federaion gateway. Created with NestJS / NodeJS

country-subgraph (http://localhost:3001/graphql) : Created with NestJS / NodeJS

food-subgraph (http://localhost:3002/graphql) : Created with NestJS / NodeJS

starwars-subgraph (http://localhost:3003/graphql) : Created with GraphQL.Net 4.7.1

Running a npm cache clean -f before installing npm dependencies strongly advised.

1 - Inside the directories federation-gateway, country-subgraph and food-subgraph run npm install

2 - Inside starwars-subgraph/WebApi run dotnet restore & dotnet build

3 - Initially federation-gateway uses country & food subgraphs. Inside their directories run yarn start:dev. You can check their individual graphs navigating to http://localhost:3001/graphql & http://localhost:3002/graphql

4 - Check federation-gateway;

federation-gateway/src/app.module.ts

      gateway: {
        buildService({ name, url }) {
          return new RemoteGraphQLDataSource({
            url,
          });
        },
        supergraphSdl: new IntrospectAndCompose({
          subgraphs: [
            {
              name: 'country',
              url: 'http://localhost:3001/graphql',
            },
            {
              name: 'food',
              url: 'http://localhost:3002/graphql',
            },
            // {
            //   name: 'starwars',
            //   url: 'http://localhost:3003/graphql',
            // },
          ],
        }),
      },

starwars subgraph is commented out for now. Start gateway by running yarn start:dev

5 - Navigate to http://localhost:3000/graphql. You can see queries & mutations form both country & food subgraphs. They can be run, but they don't have actual implementations.

6 - Let's try to add starwars subgraph to gateway. In starwars-subgraph\WebApi run dotnet run. You can see the individual graph in http://localhost:3003/graphiql-ui

7 - Now, comment out starwars part in federation-gateway/src/app.module.ts under subgraphs.

8- When you save federation-gateway/src/app.module.ts file, gateway will restart automatically. Below errors happens;

(node:3892) UnhandledPromiseRejectionWarning: Error: Couldn't load service definitions for "starwars"
    at C:\murat\graphql.net-apollo-federation\federation-gateway\node_modules\@apollo\gateway\src\supergraphManagers\IntrospectAndCompose\loadServicesFromRemoteEndpoint.ts:77:15
    at processTicksAndRejections (internal/process/task_queues.js:95:5)
    at async Promise.all (index 2)
    at loadServicesFromRemoteEndpoint (C:\murat\graphql.net-apollo-federation\federation-gateway\node_modules\@apollo\gateway\src\supergraphManagers\IntrospectAndCompose\loadServicesFromRemoteEndpoint.ts:81:30)
    at IntrospectAndCompose.updateSupergraphSdl (C:\murat\graphql.net-apollo-federation\federation-gateway\node_modules\@apollo\gateway\src\supergraphManagers\IntrospectAndCompose\index.ts:95:20)
    at IntrospectAndCompose.initialize (C:\murat\graphql.net-apollo-federation\federation-gateway\node_modules\@apollo\gateway\src\supergraphManagers\IntrospectAndCompose\index.ts:65:30)
    at ApolloGateway.initializeSupergraphManager (C:\murat\graphql.net-apollo-federation\federation-gateway\node_modules\@apollo\gateway\src\index.ts:456:22)
    at ApolloGateway.load (C:\murat\graphql.net-apollo-federation\federation-gateway\node_modules\@apollo\gateway\src\index.ts:351:7)
    at SchemaManager.start (C:\murat\graphql.net-apollo-federation\federation-gateway\node_modules\apollo-server-core\src\utils\schemaManager.ts:111:22)
    at ApolloServer._start (C:\murat\graphql.net-apollo-federation\federation-gateway\node_modules\apollo-server-core\src\ApolloServer.ts:359:24)