Dgraph integration (apollographql#253)

Dgraph currently has very limited federation support. Due to the limitations in schema declaration it is not possible to implement the expected schema:

* `ID` fields are autogenerated and cannot have custom values (in order to set custom ID we need to use `String @id`)
* unable to create type with just `ID` column (as it doesn't make sense to have a table with a single ID column)
* unable to disable auto generated field aggregate query (`Product.reserach`)
* only single field `@key` values are supported, multi column or complex type keys are not supported
* external fields have to be nullable

Author: dariuszkuc

.github/workflows/test-subgraph-dgraph.yaml

@@ -0,0 +1,14 @@
+name: Dgraph Test
+
+on:
+  pull_request:
+    branches:
+      - main
+    paths:
+      - 'implementations/dgraph/**'
+
+jobs:
+  compatibility:
+    uses: ./.github/workflows/test-subgraph.yaml
+    with:
+      library: "dgraph"

README.md

@@ -159,8 +159,9 @@ The following open-source GraphQL server libraries and hosted subgraphs provide
 </thead>
 <tbody>
 <tr><td><a href="https://aws.amazon.com/appsync/">AWS AppSync</a></td><td><table><tr><th>_service</th><td>🟢</td></tr><tr><th>@key (single)</th><td>🟢</td></tr><tr><th>@key (multi)</th><td>🟢</td></tr><tr><th>@key (composite)</th><td>🟢</td></tr><tr><th>repeatable @key</th><td>🟢</td></tr><tr><th>@requires</th><td>🟢</td></tr><tr><th>@provides</th><td>🟢</td></tr><tr><th>federated tracing</th><td>🔲</td></tr></table></td><td><table><tr><th>@link</th><td>🟢</td></tr><tr><th>@shareable</th><td>🟢</td></tr><tr><th>@tag</th><td>🟢</td></tr><tr><th>@override</th><td>🟢</td></tr><tr><th>@inaccessible</th><td>🟢</td></tr></table></td></tr>
-<tr><td><a href="https://stepzen.com/apollo-stepzen">StepZen</a></td><td><table><tr><th>_service</th><td>🟢</td></tr><tr><th>@key (single)</th><td>🟢</td></tr><tr><th>@key (multi)</th><td>🟢</td></tr><tr><th>@key (composite)</th><td>🔲</td></tr><tr><th>repeatable @key</th><td>🔲</td></tr><tr><th>@requires</th><td>🟢</td></tr><tr><th>@provides</th><td>🟢</td></tr><tr><th>federated tracing</th><td>🔲</td></tr></table></td><td><table><tr><th>@link</th><td>🟢</td></tr><tr><th>@shareable</th><td>🟢</td></tr><tr><th>@tag</th><td>🟢</td></tr><tr><th>@override</th><td>🟢</td></tr><tr><th>@inaccessible</th><td>🟢</td></tr></table></td></tr>
+<tr><td><a href="https://dgraph.io/docs/graphql/overview/">Dgraph</a></td><td><table><tr><th>_service</th><td>❌</td></tr><tr><th>@key (single)</th><td>🟢</td></tr><tr><th>@key (multi)</th><td>🔲</td></tr><tr><th>@key (composite)</th><td>🔲</td></tr><tr><th>repeatable @key</th><td>🔲</td></tr><tr><th>@requires</th><td>🔲</td></tr><tr><th>@provides</th><td>🔲</td></tr><tr><th>federated tracing</th><td>🔲</td></tr></table></td><td><table><tr><th>@link</th><td>❌</td></tr><tr><th>@shareable</th><td>🔲</td></tr><tr><th>@tag</th><td>🔲</td></tr><tr><th>@override</th><td>🔲</td></tr><tr><th>@inaccessible</th><td>🔲</td></tr></table></td></tr>
 <tr><td><a href="https://www.the-guild.dev/graphql/mesh">GraphQL Mesh</a></td><td><table><tr><th>_service</th><td>🟢</td></tr><tr><th>@key (single)</th><td>🟢</td></tr><tr><th>@key (multi)</th><td>🟢</td></tr><tr><th>@key (composite)</th><td>🟢</td></tr><tr><th>repeatable @key</th><td>🟢</td></tr><tr><th>@requires</th><td>🟢</td></tr><tr><th>@provides</th><td>🟢</td></tr><tr><th>federated tracing</th><td>🟢</td></tr></table></td><td><table><tr><th>@link</th><td>🟢</td></tr><tr><th>@shareable</th><td>🟢</td></tr><tr><th>@tag</th><td>🟢</td></tr><tr><th>@override</th><td>🟢</td></tr><tr><th>@inaccessible</th><td>🟢</td></tr></table></td></tr>
+<tr><td><a href="https://stepzen.com/apollo-stepzen">StepZen</a></td><td><table><tr><th>_service</th><td>🟢</td></tr><tr><th>@key (single)</th><td>🟢</td></tr><tr><th>@key (multi)</th><td>🟢</td></tr><tr><th>@key (composite)</th><td>🔲</td></tr><tr><th>repeatable @key</th><td>🔲</td></tr><tr><th>@requires</th><td>🟢</td></tr><tr><th>@provides</th><td>🟢</td></tr><tr><th>federated tracing</th><td>🔲</td></tr></table></td><td><table><tr><th>@link</th><td>🟢</td></tr><tr><th>@shareable</th><td>🟢</td></tr><tr><th>@tag</th><td>🟢</td></tr><tr><th>@override</th><td>🟢</td></tr><tr><th>@inaccessible</th><td>🟢</td></tr></table></td></tr>
 </tbody>
 </table>
 

implementations/dgraph/docker-compose.yaml

@@ -0,0 +1,62 @@
+# all path must be relative to the root of the project
+services:
+  dgraph:
+    image: dgraph/standalone:v21.03.2
+    environment: 
+      DGRAPH_ALPHA_GRAPHQL: 'lambda-url=http://dgraph_lambda:8686/graphql-worker'
+    ports:
+      - "8080:8080"
+      - "9080:9080"
+      - "8000:8000"
+    volumes:
+      - dgraph:/dgraph
+    healthcheck:
+        test: ["CMD", "curl", "-X", "GET", "http://dgraph:8080/admin?query=\\{health\\{status\\}\\}"]
+        interval: 15s
+        timeout: 10s
+        retries: 20
+
+  dgraph_lambda:
+    image: dgraph/dgraph-lambda:1.4.0
+    depends_on:
+      - dgraph
+    ports:
+      - "8686:8686"
+    environment:
+      DGRAPH_URL: http://dgraph:8080
+      MAX_MEMORY_LIMIT: 192M
+    volumes:
+      - ./implementations/dgraph/resolvers.js:/app/script/script.js:ro
+
+  dgraph_data:
+    image: curlimages/curl:7.85.0
+    depends_on:
+      dgraph:
+        condition: service_healthy
+    restart: "no"
+    working_dir: /app
+    volumes:
+      - ./implementations/dgraph/products.graphql:/app/products.graphql:ro
+      - ./implementations/dgraph/populateData.json:/app/populateData.json:ro
+    command:
+      - /bin/sh
+      - -c
+      - |
+        curl -v -X POST http://dgraph:8080/admin/schema --data-binary '@products.graphql'
+        curl -v -X POST -H 'Content-Type:application/json' http://dgraph:8080/graphql --data-binary '@populateData.json'
+  
+  products:
+    image: nginx:alpine
+    ports:
+      - 4001:4001
+    depends_on:
+      dgraph:
+        condition: service_healthy
+    environment:
+      DGRAPH_URL: http://dgraph:8080/graphql
+    volumes:
+      - ./implementations/dgraph/proxy.conf.template:/etc/nginx/conf.d/proxy.conf.template
+    command: /bin/sh -c "envsubst < /etc/nginx/conf.d/proxy.conf.template > /etc/nginx/conf.d/default.conf && nginx -g 'daemon off;'"
+
+volumes:
+  dgraph: {}

implementations/dgraph/metadata.yaml

@@ -0,0 +1,3 @@
+fullName: Dgraph
+language: Other Solutions
+documentation: https://dgraph.io/docs/graphql/overview/

implementations/dgraph/populateData.json

@@ -0,0 +1,65 @@
+{
+  "query": "mutation populateData($products: [AddProductInput!]!, $deprecatedProd: [AddDeprecatedProductInput!]!) { addProduct(input: $products) { numUids }, addDeprecatedProduct(input: $deprecatedProd) { numUids } }",
+  "variables": {
+    "products": [{
+      "id": "apollo-federation",
+      "sku": "federation",
+      "package": "@apollo/federation",
+      "variation": {
+        "id": "OSS"
+      },
+      "dimensions": {
+        "size": "small",
+        "weight": 1,
+        "unit": "kg"
+      },
+      "research": [
+        {
+          "study": {
+            "caseNumber": "1234",
+            "description": "Federation Study"
+          }
+        }
+      ],
+      "createdBy": {
+        "email": "[email protected]",
+        "name": "Jane Smith",
+        "totalProductsCreated": 1337
+      }
+    },{
+      "id": "apollo-studio",
+      "sku": "studi",
+      "variation": {
+        "id": "platform"
+      },
+      "dimensions": {
+        "size": "small",
+        "weight": 1,
+        "unit": "kg"
+      },
+      "research": [
+        {
+          "study": {
+            "caseNumber": "1235",
+            "description": "Studio Study"
+          }
+        }
+      ],
+      "createdBy": {
+        "email": "[email protected]",
+        "name": "Jane Smith",
+        "totalProductsCreated": 1337
+      }
+    }],
+    "deprecatedProd": [{
+      "sku": "apollo-federation-v1",
+      "package": "@apollo/federation-v1",
+      "reason": "Migrate to Federation V2",
+      "createdBy": {
+        "email": "[email protected]",
+        "name": "Jane Smith",
+        "totalProductsCreated": 1337
+      }
+    }]
+  }
+}

implementations/dgraph/products.graphql

@@ -0,0 +1,54 @@
+type Product @key(fields: "id")  @generate(query: { get: true, query: false, aggregate: false }) {
+  # dgraph does not support custom values for ID fields
+  id: String! @id
+  sku: String
+  package: String
+  variation: ProductVariation
+  dimensions: ProductDimension
+  createdBy: User @provides(fields: "totalProductsCreated")
+  notes: String
+  research: [ProductResearch!]!
+}
+
+type DeprecatedProduct @generate(query: { get: true, query: false, aggregate: false }) {
+  sku: String! @id
+  package: String! @id
+  reason: String
+  createdBy: User
+}
+
+type ProductVariation @generate(query: { get: false, query: false, aggregate: false }) {
+  id: String! @id
+  # dgraph does not allow creating types with just ID value
+  dummy: String
+}
+
+type ProductResearch @generate(query: { get: false, query: false, aggregate: false }) {
+  study: CaseStudy!
+  outcome: String
+}
+
+type CaseStudy @generate(query: { get: false, query: false, aggregate: false }) {
+  caseNumber: String! @id
+  description: String
+}
+
+type ProductDimension @generate(query: { get: false, query: false, aggregate: false }) {
+  size: String
+  weight: Float
+  unit: String
+}
+
+type Query {
+  product(id: String!): Product @lambda
+  deprecatedProduct(sku: String!, package: String!): DeprecatedProduct @deprecated(reason: "Use product query instead") @lambda
+}
+
+extend type User @key(fields: "email") @generate(query: { get: false, query: false, aggregate: false }) {
+  averageProductsCreatedPerYear: Int @requires(fields: "totalProductsCreated yearsOfEmployment") @lambda
+  email: String! @id
+  name: String
+  totalProductsCreated: Int @external
+  # dgraph does not support non-nullable external types
+  yearsOfEmployment: Int @external
+}

implementations/dgraph/proxy.conf.template

@@ -0,0 +1,8 @@
+server { 
+    listen 4001;
+    server_name products;
+    location / {
+        proxy_ssl_server_name on;
+        proxy_pass ${DGRAPH_URL};
+    }
+}

implementations/dgraph/resolvers.js

@@ -0,0 +1,43 @@
+async function productById({ args, graphql }) {
+    const results = await graphql(`query GetProductById($productId: String!) { 
+        getProduct(id: $productId) {
+            id
+            sku
+            package
+            variation { id }
+            dimensions { size weight unit }
+            createdBy { email name totalProductsCreated }
+            research { study { caseNumber description }}
+        }
+    }`, {"productId": args.id})
+    return results.data.getProduct
+  }
+
+async function deprecatedProductBySkuAndPackage({ args, graphql }) {
+    console.log("executing deprecated product by sku and package", args)
+    const results = await graphql(`query GetDeprecatedProductBySkuAndPackage($sku: String!, $pkg: String!) { 
+        getDeprecatedProduct(sku: $sku, package: $pkg) {
+            sku
+            package
+            reason
+            createdBy { email name totalProductsCreated }
+        }
+    }`, {"sku": args.sku, "pkg": args.package})
+    console.log("executed query")
+    console.log("results", results)
+    return results.data.getDeprecatedProduct
+}
+
+async function userAverageProductsCreatedPerYear({parent: {totalProductsCreated, yearsOfEmployment}}) {
+    if (totalProductsCreated) { 
+        Math.round(totalProductsCreated / yearsOfEmployment)
+      } else { 
+        null
+      }
+}
+
+self.addGraphQLResolvers({
+    "Query.product": productById,
+    "Query.deprecatedProduct": deprecatedProductBySkuAndPackage,
+    "User.averageProductsCreatedPerYear": userAverageProductsCreatedPerYear
+})

src/index.ts

@@ -54,7 +54,7 @@ async function runDockerCompose(libraryName: string, librariesPath: string) {
 
   return async () => {
     console.log(`Stopping ${libraryName} and related containers...`);
-    await execa("docker-compose", ["down", "--remove-orphans"]);
+    await execa("docker-compose", ["down", "--remove-orphans", "-v"]);
   };
 }