Federation docs and examples

.circleci/check-coverage

@@ -3,5 +3,5 @@
 set -euo pipefail
 go get github.com/mattn/goveralls
 
-go test -coverprofile=/tmp/coverage.out -coverpkg=./... $(go list github.com/99designs/gqlgen/... | grep -v server)
+go test -coverprofile=/tmp/coverage.out -coverpkg=./... $(go list github.com/99designs/gqlgen/... | grep -v example)
 goveralls -coverprofile=/tmp/coverage.out -service=circle-ci -repotoken=$REPOTOKEN -ignore='example/*/*,example/*/*/*,integration/*,integration/*/*,codegen/testserver/*'

.circleci/check-federation

@@ -0,0 +1,13 @@
+#!/bin/bash
+
+set -euo pipefail
+
+cd example/federation
+
+./start.sh &
+
+sleep 10
+
+echo "### running jest integration spec"
+./node_modules/.bin/jest --color
+

.circleci/config.yml

@@ -36,6 +36,16 @@ jobs:
       - run: cd integration ; npm install
       - run: .circleci/check-integration
 
+  federation:
+    docker:
+      - image: alpine:3.10
+    steps:
+      - checkout
+      - run: apk add --no-cache --no-progress nodejs npm go musl-dev git bash
+      - run: go mod download
+      - run: cd example/federation ; npm install
+      - run: .circleci/check-federation
+
 workflows:
   version: 2
   build_and_test:
@@ -44,4 +54,5 @@ workflows:
       - test
       - cover
       - integration
+      - federation
 

.gitignore

@@ -4,6 +4,8 @@
 /integration/node_modules
 /integration/schema-fetched.graphql
 /example/chat/package-lock.json
+/example/federation/package-lock.json
+/example/federation/node_modules
 /codegen/gen
 /gen
 

docs/content/recipes/federation.md

@@ -0,0 +1,187 @@
+---
+title: 'Using Apollo federation gqlgen'
+description: How federate many services into a single graph using Apollo
+linkTitle: Apollo Federation
+menu: { main: { parent: 'recipes' } }
+---
+
+In this quick guide we are going to implement the example [Apollo Federation](https://www.apollographql.com/docs/apollo-server/federation/introduction/)
+server in gqlgen. You can find the finished result in the [examples directory](/example/federation).
+
+
+## Create the federated servers
+
+For each server to be federated we will create a new gqlgen project.
+
+```bash
+go run github.com/99designs/gqlgen
+```
+
+Update the schema to reflect the federated example
+```graphql
+type Review {
+  body: String
+  author: User @provides(fields: "username")
+  product: Product
+}
+
+type User @extends @key(fields: "id") {
+  id: ID! @external
+  reviews: [Review]
+}
+
+type Product @extends @key(fields: "upc") {
+  upc: String! @external
+  reviews: [Review]
+}
+```
+
+> Note
+>
+> gqlgen doesnt currently support `extend type Foo` syntax for apollo federation, we must use
+> the `@extends` directive instead.
+
+
+and regenerate
+```bash
+go run github.com/99designs/gqlgen
+```
+
+then implement the resolvers
+```go
+// These two methods are required for gqlgen to resolve the internal id-only wrapper structs.
+// This boilerplate might be removed in a future version of gqlgen that can no-op id only nodes.
+func (r *entityResolver) FindProductByUpc(ctx context.Context, upc string) (*model.Product, error) {
+	return &model.Product{
+		Upc: upc,
+	}, nil
+}
+
+func (r *entityResolver) FindUserByID(ctx context.Context, id string) (*model.User, error) {
+	return &model.User{
+		ID: id,
+	}, nil
+}
+
+// Here we implement the stitched part of this service, returning reviews for a product. Of course normally you would
+// go back to the database, but we are just making some data up here.
+func (r *productResolver) Reviews(ctx context.Context, obj *model.Product) ([]*model.Review, error) {
+	switch obj.Upc {
+	case "top-1":
+		return []*model.Review{{
+			Body: "A highly effective form of birth control.",
+		}}, nil
+
+	case "top-2":
+		return []*model.Review{{
+			Body: "Fedoras are one of the most fashionable hats around and can look great with a variety of outfits.",
+		}}, nil
+
+	case "top-3":
+		return []*model.Review{{
+			Body: "This is the last straw. Hat you will wear. 11/10",
+		}}, nil
+
+	}
+	return nil, nil
+}
+
+func (r *userResolver) Reviews(ctx context.Context, obj *model.User) ([]*model.Review, error) {
+	if obj.ID == "1234" {
+		return []*model.Review{{
+			Body: "Has an odd fascination with hats.",
+		}}, nil
+	}
+	return nil, nil
+}
+```
+
+> Note
+>
+> Repeat this step for each of the services in the apollo doc (accounts, products, reviews)
+
+## Create the federation gateway
+
+```bash
+npm install --save @apollo/gateway apollo-server graphql
+```
+
+```typescript
+const { ApolloServer } = require('apollo-server');
+const { ApolloGateway } = require("@apollo/gateway");
+
+const gateway = new ApolloGateway({
+    serviceList: [
+        { name: 'accounts', url: 'http://localhost:4001/query' },
+        { name: 'products', url: 'http://localhost:4002/query' },
+        { name: 'reviews', url: 'http://localhost:4003/query' }
+    ],
+});
+
+const server = new ApolloServer({
+    gateway,
+
+    subscriptions: false,
+});
+
+server.listen().then(({ url }) => {
+    console.log(`🚀 Server ready at ${url}`);
+});
+```
+
+## Start all the services
+
+In separate terminals:
+```bash
+go run accounts/server.go
+go run products/server.go
+go run reviews/server.go
+node gateway/index.js
+```
+
+## Query the federated gateway
+
+The examples from the apollo doc should all work, eg
+
+```graphql
+query {
+  me {
+    username
+    reviews {
+      body
+      product {
+        name
+        upc
+      }
+    }
+  }
+}
+```
+
+should return
+
+```json
+{
+  "data": {
+    "me": {
+      "username": "Me",
+      "reviews": [
+        {
+          "body": "A highly effective form of birth control.",
+          "product": {
+            "name": "Trilby",
+            "upc": "top-1"
+          }
+        },
+        {
+          "body": "Fedoras are one of the most fashionable hats around and can look great with a variety of outfits.",
+          "product": {
+            "name": "Trilby",
+            "upc": "top-1"
+          }
+        }
+      ]
+    }
+  }
+}
+```

example/federation/accounts/gqlgen.yml

@@ -0,0 +1,55 @@
+# Where are all the schema files located? globs are supported eg  src/**/*.graphqls
+schema:
+  - graph/*.graphqls
+
+# Where should the generated server code go?
+exec:
+  filename: graph/generated/generated.go
+  package: generated
+
+federation:
+  filename: graph/generated/federation.go
+  package: generated
+
+# Where should any generated models go?
+model:
+  filename: graph/model/models_gen.go
+  package: model
+
+# Where should the resolver implementations go?
+resolver:
+  layout: follow-schema
+  dir: graph
+  package: graph
+
+# Optional: turn on use `gqlgen:"fieldName"` tags in your models
+# struct_tag: json
+
+# Optional: turn on to use []Thing instead of []*Thing
+# omit_slice_element_pointers: false
+
+# Optional: set to speed up generation time by not performing a final validation pass.
+# skip_validation: true
+
+# gqlgen will search for any type names in the schema in these go packages
+# if they match it will use them, otherwise it will generate them.
+autobind:
+  - "github.com/99designs/gqlgen/example/federation/accounts/graph/model"
+
+# This section declares type mapping between the GraphQL and go type systems
+#
+# The first line in each type will be used as defaults for resolver arguments and
+# modelgen, the others will be allowed when binding to fields. Configure them to
+# your liking
+models:
+  ID:
+    model:
+      - github.com/99designs/gqlgen/graphql.ID
+      - github.com/99designs/gqlgen/graphql.Int
+      - github.com/99designs/gqlgen/graphql.Int64
+      - github.com/99designs/gqlgen/graphql.Int32
+  Int:
+    model:
+      - github.com/99designs/gqlgen/graphql.Int
+      - github.com/99designs/gqlgen/graphql.Int64
+      - github.com/99designs/gqlgen/graphql.Int32

example/federation/accounts/graph/entity.resolvers.go

@@ -0,0 +1,26 @@
+// This file will be automatically regenerated based on the schema, any resolver implementations
+// will be copied through when generating and any unknown code will be moved to the end.
+package graph
+
+import (
+	"context"
+
+	"github.com/99designs/gqlgen/example/federation/accounts/graph/generated"
+	"github.com/99designs/gqlgen/example/federation/accounts/graph/model"
+)
+
+func (r *entityResolver) FindUserByID(ctx context.Context, id string) (*model.User, error) {
+	name := "User " + id
+	if id == "1234" {
+		name = "Me"
+	}
+
+	return &model.User{
+		ID:       id,
+		Username: name,
+	}, nil
+}
+
+func (r *Resolver) Entity() generated.EntityResolver { return &entityResolver{r} }
+
+type entityResolver struct{ *Resolver }