GraphQL Federation Development Server

A development server for Apollo Federation that allows you to run and test GraphQL subgraphs locally. This tool helps you develop and test federated GraphQL schemas by providing mock data and automatic schema composition.

Features

• Run multiple GraphQL subgraphs locally
• Automatic mock data generation for GraphQL types
• Customizable mock data using directives
• Real-time schema watching and reloading
• Supergraph composition with Apollo Federation
• Fetch new GraphQL schemas from Apollo Studio

Installation

Download the latest release from the GitHub releases page or build from source.

Usage

The tool provides two main commands: serve and fetch.

Serve Command

Run a local development server with multiple subgraphs, suitable for exposing to Apollo Router:

graphql-federation-dev serve --schemas subgraph1=./schemas/subgraph1.graphql --schemas subgraph2=./schemas/subgraph2.graphql --output ./supergraph.graphql

Serve Composed Supergraph

Once the server is running, it will automatically compose the supergraph schema from the provided subgraphs into the indicated file (supergraph.graphql). You can then launch Apollo Router against these mock subgraphs:

router -c router-config.yaml -s supergraph.graphql

New Command

Create a new federated GraphQL project with multiple subgraphs:

graphql-federation-dev new ./my-project --subgraph users --subgraph products

This will create a new project directory with basic schema files for each specified subgraph.

Fetch Command

Generate a new GraphQL schema from an Apollo Studio proposal:

graphql-federation-dev fetch --proposal-number 123 ./output-directory

Command Line Options

Global Options

Option	Description	Default
--pretty-traces	Enable pretty-printed traces for debugging	false

Serve Command Options

Option	Description	Default
--schemas, -s	Schema files in the format subgraph=file_name.graphql	Required
--output, -o	Output path for the composed supergraph schema	Required
--port	Port to run the server on	8080

New Command Options

Option	Description	Default
--subgraph, -s	Names of subgraphs to create	Required
path	Path to the folder where the project will be created	Required

Fetch Command Options

Option	Description	Default
--proposal-number, -p	Apollo Studio proposal number	Required
path	Path to the folder where the schema will be created	Required

Mock Data Directives

The server generates mock data for your GraphQL types. You can customize this data using the following directives:

@words(min: Int, max: Int)

Generates random text with a specified number of words.

type User {
  bio: String @words(min: 10, max: 20)
}

@select(from: [String])

Selects a random value from a provided list.

type Product {
  category: String @select(from: ["Electronics", "Clothing", "Books", "Home"])
}

@count(min: Int, max: Int)

Specifies the number of items in a list.

type User {
  tags: [String!]! @count(min: 2, max: 5)
}

Example Schema

type Query {
  user: User
  products: [Product!]! @count(min: 3, max: 10)
}

type User {
  id: ID!
  username: String @words(min: 1, max: 2)
  name: String @select(from: ["John Doe", "Jane Smith", "Alex Johnson"])
  bio: String @words(min: 10, max: 30)
  favoriteProducts: [Product!]! @count(min: 1, max: 3)
}

type Product {
  id: ID!
  name: String @words(min: 2, max: 4)
  category: String @select(from: ["Electronics", "Clothing", "Books"])
  price: Float
  inStock: Boolean
}

Federation Support

This server supports Apollo Federation directives and features, allowing you to develop and test federated GraphQL schemas locally.

type User @key(fields: "id") {
  id: ID!
  username: String
}

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

Development

To build and run the project locally:

cargo build
cargo run -- --schemas example=./example.graphql --output ./supergraph.graphql

License

MIT