Add sangria as library implementing GraphQL Federation (#237)

One test is still mising: with @link

Fix #232

Author: yanns

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

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

implementations/sangria/.scalafmt.conf

@@ -0,0 +1,4 @@
+version = "3.1.1"
+runner.dialect = scala213
+
+maxColumn = 120

implementations/sangria/Dockerfile

@@ -0,0 +1,8 @@
+FROM hseeberger/scala-sbt:17.0.2_1.6.2_3.1.1 AS build
+
+WORKDIR /build
+COPY project/build.properties ./project/
+COPY build.sbt ./
+COPY src ./src
+EXPOSE 4001
+CMD sbt run

implementations/sangria/README.md

@@ -0,0 +1,18 @@
+# federated subgraph with sangria
+
+Implementation of a federated subgraph based on the scala library [sangria](https://sangria-graphql.github.io/).
+
+
+# Usage
+
+## Starting the GraphQL server
+
+```
+sbt run
+```
+
+## Printing the GraphQL schema (SQL)
+
+```
+sbt "run printSchema"
+```

implementations/sangria/build.sbt

@@ -0,0 +1,18 @@
+import sbt._
+
+version := "1.0.0"
+scalaVersion := "2.13.9"
+
+val http4sVersion = "1.0.0-M37"
+val circeVersion = "0.14.3"
+
+libraryDependencies ++= List(
+  "org.sangria-graphql" %% "sangria-federated" % "0.3.0",
+  "org.sangria-graphql" %% "sangria-circe" % "1.3.2",
+  "org.http4s" %% "http4s-ember-server" % http4sVersion,
+  "org.http4s" %% "http4s-dsl" % http4sVersion,
+  "org.http4s" %% "http4s-circe" % http4sVersion,
+  "io.circe" %% "circe-core" % circeVersion,
+  "io.circe" %% "circe-generic" % circeVersion,
+  "io.circe" %% "circe-optics" % "0.14.1"
+)

implementations/sangria/docker-compose.yaml

@@ -0,0 +1,6 @@
+services:
+  products:
+    # must be relative to the root of the project
+    build: implementations/sangria
+    ports:
+      - 4001:4001

implementations/sangria/metadata.yaml

@@ -0,0 +1,3 @@
+fullName: Sangria
+language: Scala
+documentation: https://sangria-graphql.github.io/learn/#graphql-federation

implementations/sangria/products.graphql

@@ -0,0 +1,56 @@
+extend schema
+  @link(
+    url: "https://specs.apollo.dev/federation/v2.0",
+    import: ["@extends", "@external", "@inaccessible", "@key", "@override", "@provides", "@requires", "@shareable", "@tag"]
+  )
+
+type Product @key(fields: "id") @key(fields: "sku package") @key(fields: "sku variation { id }") {
+  id: ID!
+  sku: String
+  package: String
+  variation: ProductVariation
+  dimensions: ProductDimension
+  createdBy: User @provides(fields: "totalProductsCreated")
+  notes: String @tag(name: "internal")
+  research: [ProductResearch!]!
+}
+
+type DeprecatedProduct @key(fields: "sku package") {
+  sku: String!
+  package: String!
+  reason: String
+  createdBy: User
+}
+
+type ProductVariation {
+  id: ID!
+}
+
+type ProductResearch @key(fields: "study { caseNumber }") {
+  study: CaseStudy!
+  outcome: String
+}
+
+type CaseStudy {
+  caseNumber: ID!
+  description: String
+}
+
+type ProductDimension @shareable {
+  size: String
+  weight: Float
+  unit: String @inaccessible
+}
+
+extend type Query {
+  product(id: ID!): Product
+  deprecatedProduct(sku: String!, package: String!): DeprecatedProduct @deprecated(reason: "Use product query instead")
+}
+
+type User @key(fields: "email") {
+  averageProductsCreatedPerYear: Int @requires(fields: "totalProductsCreated yearsOfEmployment")
+  email: ID! @external
+  name: String @override(from: "users")
+  totalProductsCreated: Int @external
+  yearsOfEmployment: Int! @external
+}

implementations/sangria/project/build.properties

@@ -0,0 +1 @@
+sbt.version=1.6.2

implementations/sangria/src/main/scala/Main.scala

@@ -0,0 +1,57 @@
+import cats.effect.{ExitCode, IO, IOApp}
+import com.comcast.ip4s.IpLiteralSyntax
+import graphql.{AppContext, GraphQLSchema, ProductGraphQLSchema, UserGraphQLSchema}
+import http.{GraphQLExecutor, GraphQLServer}
+import io.circe.Json
+import sangria.federation.v2.Federation
+import sangria.marshalling.InputUnmarshaller
+import sangria.renderer.QueryRenderer
+import sangria.schema.Schema
+import service.{ProductResearchService, ProductService, UserService}
+
+object Main extends IOApp {
+
+  override def run(args: List[String]): IO[ExitCode] = (args match {
+    case "printSchema" :: Nil => printSchema
+    case _                    => runGraphQLServer
+  }).as(ExitCode.Success)
+
+  private def printSchema: IO[Unit] =
+    for {
+      schema <- IO(schemaAndUm).map(_._1)
+      _ <- IO.println(QueryRenderer.renderPretty(schema.toAst))
+    } yield ()
+
+  private def runGraphQLServer: IO[Unit] =
+    for {
+      ctx <- appContext
+      executor <- graphQLExecutor(ctx)
+      host = host"0.0.0.0"
+      port = port"4001"
+      _ <- IO.println(s"starting GraphQL HTTP server on http://$host:$port")
+      _ <- GraphQLServer.bind(executor, host, port).use(_ => IO.never)
+    } yield ()
+
+  private def appContext: IO[AppContext] = IO {
+    new AppContext {
+      override def productService: ProductService = ProductService.inMemory
+      override def productResearchService: ProductResearchService = ProductResearchService.inMemory
+      override def userService: UserService = UserService.inMemory
+    }
+  }
+
+  private def schemaAndUm: (Schema[AppContext, Unit], InputUnmarshaller[Json]) =
+    Federation.federate(
+      GraphQLSchema.schema,
+      sangria.marshalling.circe.CirceInputUnmarshaller,
+      ProductGraphQLSchema.productResolver,
+      ProductGraphQLSchema.deprecatedProductResolver,
+      ProductGraphQLSchema.productResearchResolver,
+      UserGraphQLSchema.userResolver
+    )
+
+  private def graphQLExecutor(context: AppContext): IO[GraphQLExecutor[AppContext]] = IO {
+    val (schema, um) = schemaAndUm
+    GraphQLExecutor(schema, context)(um)
+  }
+}