.NET HotChocolate Federated GraphQL Subgraph

This is an example application template that can be used to create a Federated GraphQL subgraph using HotChocolate. You can use this template from Rover with rover template use --template subgraph-csharp-hotchocolate-annotation.

This example application implements the following GraphQL schema:

extend schema
  @link(url: "https://specs.apollo.dev/federation/v2.5", import: ["@key"])

type Query {
  thing(id: ID!): Thing
}

type Mutation {
  createThing(thing: CreateThing!): Thing
}

type Thing @key(fields: "id") {
  id: ID!
  name: String
}

input CreateThing {
  id: ID!
  name: String
}

Build

This project uses .NET CLI and requires .NET 7.0+ runtime. In order to build the project locally, run:

dotnet build

To test the project, run:

dotnet test

Continuous Integration

This project comes with some example build actions that will trigger on PR requests and commits to the main branch.

Run

To start the GraphQL server:

# from root directory
dotnet run --project Server

# from Server directory
dotnet run

Once the app has started, you can explore the example schema by opening the Banana Cake Pop IDE at http://localhost:4001/ or http://localhost:4001/graphql and begin developing your supergraph with rover dev --url http://localhost:4001/graphql --name my-subgraph.

Debug in VS Code

There is a launch configuration for both the Server project and the Tests project that you can debug with VS Code. Open up the debug panel in VS Code and press the play button.

GraphOS Integration

1. Set these secrets in GitHub Actions:
   1. APOLLO_KEY: An Apollo Studio API key for the supergraph to enable schema checks and publishing of the subgraph. Check the Apollo documentation for how to obtain this API key.
   2. APOLLO_GRAPH_REF: A string with the following format: graph_id@variant_name. You can find your graph's ID in that graph's Settings page in Studio.
   3. PRODUCTION_URL: The URL of the deployed subgraph.
2. Set SUBGRAPH_NAME in .github/workflows/checks.yaml and .github/workflows/deploy.yaml
3. Remove the if: false lines from .github/workflows/checks.yaml and .github/workflows/deploy.yaml to enable schema checks and publishing.
4. Write your custom deploy logic in .github/workflows/deploy.yaml.
5. Send the Router-Authorization header from your Cloud router and set the ROUTER_SECRET environment variable wherever you deploy this to.

Additional Resources

• HotChocolate documentation
• .NET SDK documentation
• .NET CLI documentation