stitcher_simplified.js

const monolith_url: string = process.env.APOLLO_URL
const file_manager_url: string = process.env.FILE_MANAGER_URL


async function run() {
    // logic on how extract files from file microservice
    function getBatchFiles(context) {
        return function batchFiles(keys: string[]): Promise<Array<{} | null>> {
            return new Promise(function (resolve, reject) {
                // query file microservice here
            })
        }
    }
const createRemoteSchema = async (uri: string) => {
  const http = new HttpLink({ uri, fetch });
        const link = setContext((request, previousContext) => ({
            headers: (previousContext.graphqlContext || {}).headers
        })).concat(http);
        try {
            return makeRemoteExecutableSchema({
                schema: await introspectSchema(link),
                link
            });
        }catch (e) {
            console.error(e);
        }
 };
const monolithSchema = await createRemoteSchema(apollo_url);
const fileSchema = await createRemoteSchema(file_manager_url);
let schemas:any = [];
schemas.push(monolithSchema);
schemas.push(fileSchema)
const linkSchemaDefs = `
 extend type MessageNode {
     file: [FileNode]
 }
    `;
// define how 2 schemas of monolith and filemanager will be combined
 let schema = mergeSchemas({
  schemas: schemas,
  resolvers: mergeInfo => (resolvers)
 });
const app = express();
const server = new ApolloServer({schema});
server.applyMiddleware({app});
 app.listen(3000);
 console.log('Server running. Open http://localhost:3000/graphql to run queries.');
}
run().catch(e => {
    console.error(e, e.message, e.stack);
});