The Supergraph Top-N Challenge

Context: We ran this challenge at GraphQL Conf and because of the interesting results that we saw, we decided to run it again for Hacktoberfest 🎉

Winner takes a $1000 prize. Can you build and execute the fastest GraphQL gateway?

Build a supergraph that processes a simple “top N” query that fetches data from 2 domain services (backed by 2 different databases)
Lowest P95 at 100 RPS wins!
Use any stack or approach to build the GraphQL server. Eg: GraphQL federation or schema stitching or GraphQL gateway talking to 2 different REST/gRPC services.

You have to build:

The GraphQL server (ref: GraphQL gateway in diagram below)
The 2 domain services (ref: Threads service, and Posts service in diagram below)

Submit a link to your git repository as a Github Issue!

Deadline: Submit your entry by Tuesday, October 31, 12:00am PT (midnight).

We think this is a fantastic minimal problem to showcase different methods of building supergraphs. Did you have another solution? Please stop by the Issues page and add your notes!

Regards, Team Hasura.

Problem Statement

You have two postgres databases. One contains the threads table and another contains the posts table.

The GraphQL gateway must be able to process the following query: retrieve the first n threads sorted by created descending and for each, return the first m posts sorted by created descending.

query {
  threads(limit: n) { # From Threads service
    id
    posts(limit: m) { # From Posts service
      id
    }
  }
}

The system mirrors the common pattern of having a domain service that resolves queries for each database, and a separate gateway component.

Goal

While the challenge and prize money makes it fun, the goal of this challenge is really to highlight the different approaches & design decisions that go into building the GraphQL gateway and how domain services get unified.

The Hasura team will put together a blogpost summarizing the different stacks and design approaches used by the participants!

Environment and Setup

Use the provided database docker-compose-db.yaml file to start the two database services with preloaded test data
- Use the ports bound on localhost to address the databases
- Do not modify or optimise the database services
- You can use the command docker compose -f docker-compose-db.yaml up -d to start the databases
- The test bench will run these containers alongside the services you provide
In an independent repository / directory, build the remaining three services as separate docker containers
- Serve the gateway on port 8000
This repository must contain one docker-compose.yml that describes all the services
The test bench will run docker compose up in this directory, and this should completely initialise all three services

Your system will be run on an GCE E2 instance with 2 vCPU and 4 GB RAM by the test bench post submission.

Acceptance Criteria

Your repository must contain one docker-compose.yml that completely describes the three services (do not include the two database services provided)
The gateway endpoint must serve GraphQL
- Inter-service protocol need not be (but can be) GraphQL
Do not implement query based response caching in your services (our test bench is pretty simple)
The single query endpoint must return the data in the JSON format shown in the examples, but may contain additional root level properties

Test Cases / Examples

These are based on the provided dataset, please use them to confirm your responses' correctness.

We have assumed the argument name as limit as the examples show.

Case 1

query ($threadLimit: Int!, $postLimit: Int!) {
  threads (limit: $threadLimit) {
    id
    posts (limit: $postLimit) {
      id
    }
  }
}

and we give the threadLimit as 1 and postLimit as 2. The response should be as below:

{
  "data": {
    "threads": [
      {
        "id": 212991383,
        "posts": [
          {
            "id": 1300957267
          },
          {
            "id": 1679625662
          }
        ]
      }
    ]
  }
}

Case 2

Limit values being updated for the respective variables. For threadLimit to be 2 and postLimit to be 1, the response should be like the one below:

{
  "data": {
    "threads": [
      {
        "id": 212991383,
        "posts": [
          {
            "id": 1300957267
          }
        ]
      },
      {
        "id": 1194533456,
        "posts": [
          {
            "id": 1206315650
          }
        ]
      }
    ]
  }
}

Submission

Once your supergraph is ready, open a PR on submissions.md and add your name, submission date and link to the supergraph repository.

Prizes

Prizes are Amazon gift cards.

Winner: $1000
Runners-up: $750, $500

While you're welcome to submit as many entries as you like, please note that each person is eligible for only one prize.

Questions and Support

For any questions or support, just open a Github Issue on this repo!

hasura / supergraph-top-n-challenge