nest/sample/32-graphql-federation-schema-first

GraphQL Federation - Schema First

A production-ready example of GraphQL Federation using Schema First approach.

Installation

Install dependencies for all applications:

cd users-application && npm install
cd ../posts-application && npm install
cd ../gateway && npm install

Execution

Development Mode

For development, the gateway will automatically generate a supergraph schema from local schema files:

# Start sub-graph applications first
cd users-application && npm run start

cd posts-application && npm run start

# The gateway will auto-generate supergraph.graphql and TypeScript types on startup
cd gateway && npm run start

Production Mode

For production, generate the supergraph schema and types beforehand:

# 1. Ensure sub-graphs are running (for Rover CLI method)
cd users-application && npm run start
cd ../posts-application && npm run start

# 2. Generate supergraph schema using Rover CLI (requires @apollo/rover installation)
cd ../gateway && npm run generate:supergraph:rover

# 3. Generate TypeScript types from supergraph
npm run generate:typings

# 4. Start the gateway with the static supergraph
npm run start:prod

Schema Generation

The gateway provides multiple generation scripts:

1. Supergraph Generation (Local): npm run generate:supergraph

   • Composes supergraph from local .graphql files
   • Suitable for development when sub-graphs share the same repository

2. Supergraph Generation (Rover): npm run generate:supergraph:rover

   • Uses Apollo Rover to compose supergraph from running sub-graphs
   • Requires Rover CLI: npm install -g @apollo/rover
   • Recommended for production deployments

3. TypeScript Types Generation: npm run generate:typings

   • Generates TypeScript interfaces from the supergraph schema
   • Provides type safety for resolvers and GraphQL operations

Access the graph

You can reach the gateway under http://localhost:3002/graphql

Query a combined graph

query getUserWithPosts($userId: ID!) {
  getUser(id: $userId) {
    id
    name
    posts {
      authorId
      id
      title
    }
  }
}