GraphQL Federation Proof-of-Concept

A simple prototype using Apollo GraphQL Federation to combine two small elixir Graphql services

Setup

We have 3 services. Start the elixir services first, then run the federator.

• product_api
  • cd product_api && mix deps.get && iex -S mix
  • runs on port 3010 by default (see config/config.exs)
  • example query:

query test {
  product: product(id: 1) {
    name
    brand
  }

• user_api
  • cd user_api && mix deps.get && iex -S mix
  • runs on port 3020 by default (see config/config.exs)
  • example query:

query test {
  user: fetchUserById(id: 3) {
    email
  }
}

• federator
  • cd federator && npm install && npm start server
  • runs on port 4000 by default

Try it out

Send this query to the federator:

query test {
  # from the user service
  user: fetchUserById(id: 2) {
    email
  }
  # from the product service
  product: product(id: 2) {
    name
    brand
  }
  # from both, using federation
  user_with_products: fetchUserById(id: 1) {
    products {
      name
      brand
      priceUSD
    }
    email
  }
}

You should see this response

{
  "data": {
    "user": {
      "email": "[email protected]"
    },
    "product": {
      "name": "Blue Hat",
      "brand": "Balenciaga"
    },
    "user_with_products": {
      "products": [
        {
          "name": "Red Belt",
          "brand": "Gucci",
          "priceUSD": 1000
        },
        {
          "name": "Blue Hat",
          "brand": "Balenciaga",
          "priceUSD": 2000
        },
        {
          "name": "Green Scarf",
          "brand": "Vetements",
          "priceUSD": 3000
        }
      ],
      "email": "[email protected]"
    }
  }
}

Read More:

Federation Specs

License

Released under the MIT License.