console/packages/libraries/external-composition/example.mjs

/* eslint-disable */
/// @ts-check
import fastify from 'fastify';
import { parse, printSchema } from 'graphql';
import { composeServices } from '@apollo/composition';
import { compose, signatureHeaderName, verifyRequest } from './src/index';

if (typeof process.env.PORT === 'undefined') {
  throw new Error('PORT environment variable must be set');
}

if (typeof process.env.SECRET === 'undefined') {
  throw new Error('SECRET environment variable must be set');
}

const SECRET = process.env.SECRET;
const PORT = process.env.PORT;

/**
 * @type string[]
 */
const history = [];

const composeFederation = compose(services => {
  try {
    const result = composeServices(
      services.map(service => {
        history.push(service.name);
        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' &&
              // `INVALID_GRAPHQL` is a special error code that is used to indicate that the error comes from GraphQL-JS
              error.extensions.code !== 'INVALID_GRAPHQL'
                ? 'composition'
                : 'graphql',
          })),
        },
      };
    }

    if (!result.supergraphSdl) {
      return {
        type: 'failure',
        result: {
          errors: [
            {
              message: 'supergraphSdl not defined',
              source: 'graphql',
            },
          ],
        },
      };
    }

    return {
      type: 'success',
      result: {
        supergraph: result.supergraphSdl,
        sdl: printSchema(result.schema.toGraphQLJSSchema()),
      },
    };
  } catch (e) {
    return {
      type: 'failure',
      result: {
        errors: [
          {
            message: String(e),
            source: 'graphql',
          },
        ],
      },
    };
  }
});

async function main() {
  const server = fastify({});

  server.route({
    method: ['GET'],
    url: '/_history',
    handler(_, res) {
      res.send(JSON.stringify(history));
    },
  });

  server.route({
    method: ['GET', 'OPTIONS'],
    url: '/_readiness',
    handler(_, res) {
      res.status(200).send('OK');
    },
  });

  server.route({
    method: ['POST'],
    url: '/compose',
    handler(req, res) {
      /**
       * @type any
       */
      const signature = req.headers[signatureHeaderName];
      const error = verifyRequest({
        body: JSON.stringify(req.body),
        signature: signature,
        secret: SECRET,
      });

      if (error) {
        // Failed to verify the request
        res.status(500).send(error);
      } else {
        /**
         * @type any
         */
        const input = req.body;
        const result = composeFederation(input);
        res.send(JSON.stringify(result));
      }
    },
  });

  /**
   * used for testing
   */

  server.route({
    method: ['POST'],
    url: '/fail_on_signature',
    handler(req, res) {
      /**
       * @type any
       */
      const signature = req.headers[signatureHeaderName];
      const error = verifyRequest({
        body: JSON.stringify(req.body),
        signature: signature,
        secret: SECRET + 'wrong = fail',
      });

      if (error) {
        // Failed to verify the request
        res.status(500).send(error);
      } else {
        /**
         * @type any
         */
        const input = req.body;
        const result = composeFederation(input);
        res.send(JSON.stringify(result));
      }
    },
  });

  server.route({
    method: ['POST'],
    url: '/timeout',
    handler(_req, res) {
      setTimeout(() => {
        res.status(500).send('did not expect to get here');
      }, 35_000);
    },
  });

  /**
   * ok, we're back from testing
   */

  await server.listen({
    port: parseInt(PORT, 10),
    host: '::',
  });

  console.log(`Server listening on port ${PORT}`);
}

main().catch(err => {
  console.error(err);
  process.exit(1);
});