nest/sample/31-graphql-federation-code-first

GraphQL Federation - Code First

A production-ready example of GraphQL Federation using Code 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 on startup:

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

cd posts-application && npm run start

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

Production Mode

For production, generate the supergraph schema beforehand:

# 1. Ensure sub-graphs are running
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. Start the gateway with the static supergraph
npm run start:prod

Supergraph Schema Generation

The gateway provides two methods for generating the supergraph schema:

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

   • Generates a simplified supergraph for local development
   • Does not require Rover CLI

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

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

Access the graph

You can reach the gateway under http://localhost:3001/graphql

Query a combined graph

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