Store

Dev Set up

# install subgraphs & gateway deps
cd subgraphs/products && npm i 
cd subgraphs/customer && npm i 
cd subgraphs/shipping && npm i
cd gateway && npm i 

# start the subgraphs
npm run start:dev

# 🚀 Subgraph customer running at http://localhost:5010/
# 🚀 Subgraph products running at http://localhost:5020/
# 🚀 Subgraph shipping running at http://localhost:5030/

# exportAPOLLO_KEY=service:SECRET
# start the gateway
npm run start:gw
# 🚀 Gateway ready at http://localhost:4000/

Desired State

# shipping subgraph
query {
  shippingReference {
    id
    orderNumber
    shippingEstimate # query planner calls customer & products
  }
}

Sample schema definition, utilizing @requires.

Example of @provides

We can use @provides on an field resolved by another subgraph, to override their value. In this example, we have the field Product.description. While "description" can be resolved in the Product subgraph, the Shipping subgraph has its own value for it, and wants to return it for queries calling this service.

Observe the query

query InStockCount{
  inStockCount(shippingId: "1") {
    quantity
    product {
      id
      description
    }
  }
}
// response
{
  "data": {
    "inStockCount": {
      "quantity": 100,
      "product": {
        "id": "1",
        "description": "Duis aute irure dolor in reprehenderit in voluptate velit esse cillum."
      }
    }
  }
}

This yields the query plan below. It instructs the gateway that for this query, it doesn't need to invoke the Product subgraph because the field is resolved here.

QueryPlan {
  Fetch(service: "shipping") {
    {
      inStockCount(shippingId: $shippingId) {
        quantity
        product {
          id
          description
        }
      }
    }
  },
}

Now the Shipping subgraph doesn't return the Product.name for which the gateway then needs to call the Product subgraph

query InStockCount {
  inStockCount(shippingId: "1") {
    quantity
    product {
      id
      name
      description
    }
  }
}
//response
{
  "data": {
    "inStockCount": {
      "quantity": 100,
      "product": {
        "id": "1",
        "name": "Pants",
        "description": "Duis aute irure dolor in reprehenderit in voluptate velit esse cillum."
      }
    }
  }
}

Execution plan:

QueryPlan {
  Sequence {
    Fetch(service: "shipping") {
      {
        inStockCount(shippingId: $shippingId) {
          product {
            __typename
            id
            description
          }
          quantity
        }
      }
    },
    Flatten(path: "inStockCount.product") {
      Fetch(service: "products") {
        {
          ... on Product {
            __typename
            id
          }
        } =>
        {
          ... on Product {
            name
          }
        }
      },
    },
  },
}

OpenTelemetry

export APOLLO_OTEL_EXPORTER_TYPE=collector
export APOLLO_OTEL_EXPORTER_HOST=collector
export APOLLO_OTEL_EXPORTER_PORT=4318

Collector

npm install @opentelemetry/node
@opentelemetry/plugin-http
@opentelemetry/plugin-express