add ktor server plugin module (ExpediaGroup#1667)

### 📝 Description

Creates Ktor GraphQL Plugin with similar functionality as the existing SpringBoot auto-configuration module.

```kotlin
fun Application.graphQLModule() {
    install(GraphQL) {
        schema {
            packages = listOf("com.example")
            queries = listOf(HelloWorldQuery())
        }
    }
}
```

### 🔗 Related Issues

Resolves: ExpediaGroup#1471
---------

Co-authored-by: Jean-Michel Fayard <[email protected]>

Author: dariuszkuc

examples/server/ktor-server/build.gradle.kts

@@ -12,8 +12,7 @@ application {
 }
 
 dependencies {
-    implementation("com.expediagroup", "graphql-kotlin-server")
-    implementation(libs.ktor.server.core)
+    implementation("com.expediagroup", "graphql-kotlin-ktor-server")
     implementation(libs.ktor.server.netty)
     implementation(libs.logback)
     implementation(libs.kotlinx.coroutines.jdk8)

examples/server/ktor-server/src/main/kotlin/com/expediagroup/graphql/examples/server/ktor/KtorGraphQLContextFactory.kt renamed to examples/server/ktor-server/src/main/kotlin/com/expediagroup/graphql/examples/server/ktor/CustomGraphQLContextFactory.kt

@@ -16,27 +16,29 @@
 
 package com.expediagroup.graphql.examples.server.ktor
 
-import com.expediagroup.graphql.generator.extensions.toGraphQLContext
 import com.expediagroup.graphql.examples.server.ktor.schema.models.User
-import com.expediagroup.graphql.server.execution.GraphQLContextFactory
+import com.expediagroup.graphql.generator.extensions.plus
+import com.expediagroup.graphql.server.ktor.DefaultKtorGraphQLContextFactory
 import io.ktor.server.request.ApplicationRequest
 import graphql.GraphQLContext
 
 /**
  * Custom logic for how this example app should create its context given the [ApplicationRequest]
  */
-class KtorGraphQLContextFactory : GraphQLContextFactory<ApplicationRequest> {
+class CustomGraphQLContextFactory : DefaultKtorGraphQLContextFactory() {
     override suspend fun generateContext(request: ApplicationRequest): GraphQLContext =
-        mutableMapOf<Any, Any>(
-            "user" to User(
-                email = "[email protected]",
-                firstName = "Someone",
-                lastName = "You Don't know",
-                universityId = 4
-            )
-        ).also { map ->
-            request.headers["my-custom-header"]?.let { customHeader ->
-                map["customHeader"] = customHeader
+        super.generateContext(request).plus(
+            mutableMapOf<Any, Any>(
+                "user" to User(
+                    email = "[email protected]",
+                    firstName = "Someone",
+                    lastName = "You Don't know",
+                    universityId = 4
+                )
+            ).also { map ->
+                request.headers["my-custom-header"]?.let { customHeader ->
+                    map["customHeader"] = customHeader
+                }
             }
-        }.toGraphQLContext()
+        )
 }

examples/server/ktor-server/src/main/kotlin/com/expediagroup/graphql/examples/server/ktor/GraphQLModule.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2022 Expedia, Inc
+ * Copyright 2023 Expedia, Inc
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -13,40 +13,42 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
 package com.expediagroup.graphql.examples.server.ktor
 
-import com.expediagroup.graphql.generator.extensions.print
-import io.ktor.http.ContentType
+import com.expediagroup.graphql.dataloader.KotlinDataLoaderRegistryFactory
+import com.expediagroup.graphql.examples.server.ktor.schema.BookQueryService
+import com.expediagroup.graphql.examples.server.ktor.schema.CourseQueryService
+import com.expediagroup.graphql.examples.server.ktor.schema.HelloQueryService
+import com.expediagroup.graphql.examples.server.ktor.schema.LoginMutationService
+import com.expediagroup.graphql.examples.server.ktor.schema.UniversityQueryService
+import com.expediagroup.graphql.examples.server.ktor.schema.dataloaders.BookDataLoader
+import com.expediagroup.graphql.examples.server.ktor.schema.dataloaders.CourseDataLoader
+import com.expediagroup.graphql.examples.server.ktor.schema.dataloaders.UniversityDataLoader
+import com.expediagroup.graphql.server.ktor.GraphQL
 import io.ktor.server.application.Application
-import io.ktor.server.application.call
 import io.ktor.server.application.install
-import io.ktor.server.response.respondText
-import io.ktor.server.routing.Routing
-import io.ktor.server.routing.get
-import io.ktor.server.routing.post
-import io.ktor.server.routing.routing
 
 fun Application.graphQLModule() {
-    install(Routing)
-
-    routing {
-        post("graphql") {
-            KtorServer().handle(this.call)
+    install(GraphQL) {
+        schema {
+            packages = listOf("com.expediagroup.graphql.examples.server")
+            queries = listOf(
+                HelloQueryService(),
+                BookQueryService(),
+                CourseQueryService(),
+                UniversityQueryService(),
+            )
+            mutations = listOf(
+                LoginMutationService()
+            )
         }
-
-        get("sdl") {
-            call.respondText(graphQLSchema.print())
+        engine {
+            dataLoaderRegistryFactory = KotlinDataLoaderRegistryFactory(
+                UniversityDataLoader, CourseDataLoader, BookDataLoader
+            )
         }
-
-        get("playground") {
-            this.call.respondText(buildPlaygroundHtml("graphql", "subscriptions"), ContentType.Text.Html)
+        server {
+            contextFactory = CustomGraphQLContextFactory()
         }
     }
 }
-
-private fun buildPlaygroundHtml(graphQLEndpoint: String, subscriptionsEndpoint: String) =
-    Application::class.java.classLoader.getResource("graphql-playground.html")?.readText()
-        ?.replace("\${graphQLEndpoint}", graphQLEndpoint)
-        ?.replace("\${subscriptionsEndpoint}", subscriptionsEndpoint)
-        ?: throw IllegalStateException("graphql-playground.html cannot be found in the classpath")

examples/server/ktor-server/src/main/kotlin/com/expediagroup/graphql/examples/server/ktor/KtorGraphQLRequestParser.kt

@@ -68,6 +68,8 @@ ktor-client-cio = { group = "io.ktor", name = "ktor-client-cio", version.ref = "
 ktor-client-content = { group = "io.ktor", name = "ktor-client-content-negotiation", version.ref = "ktor" }
 ktor-client-serialization = { group = "io.ktor", name = "ktor-client-serialization", version.ref = "ktor" }
 ktor-serialization-jackson = { group = "io.ktor", name = "ktor-serialization-jackson", version.ref = "ktor" }
+ktor-server-core = { group = "io.ktor", name = "ktor-server-core", version.ref = "ktor" }
+ktor-server-content = { group = "io.ktor", name = "ktor-server-content-negotiation", version.ref = "ktor" }
 maven-plugin-annotations = { group = "org.apache.maven.plugin-tools", name = "maven-plugin-annotations", version.ref = "maven-plugin-annotation" }
 maven-plugin-api = { group = "org.apache.maven", name = "maven-plugin-api", version.ref = "maven-plugin-api" }
 maven-project = { group = "org.apache.maven", name = "maven-project", version.ref = "maven-project" }
@@ -91,7 +93,6 @@ kotlinx-benchmark = { group = "org.jetbrains.kotlinx", name = "kotlinx-benchmark
 kotlinx-coroutines-test = { group = "org.jetbrains.kotlinx", name = "kotlinx-coroutines-test", version.ref = "kotlinx-coroutines" }
 ktor-client-logging = { group = "io.ktor", name = "ktor-client-logging", version.ref = "ktor" }
 ktor-client-okhttp = { group = "io.ktor", name = "ktor-client-okhttp", version.ref = "ktor" }
-ktor-server-core = { group = "io.ktor", name = "ktor-server-core", version.ref = "ktor" }
 ktor-server-cio = { group = "io.ktor", name = "ktor-server-cio", version.ref = "ktor" }
 ktor-server-netty = { group = "io.ktor", name = "ktor-server-netty", version.ref = "ktor" }
 ktor-server-test-host = { group = "io.ktor", name = "ktor-server-test-host", version.ref = "ktor" }

examples/server/ktor-server/src/main/kotlin/com/expediagroup/graphql/examples/server/ktor/KtorServer.kt

@@ -0,0 +1,36 @@
+description = "GraphQL plugin for Ktor servers"
+
+plugins {
+    id("com.expediagroup.graphql.conventions")
+}
+
+dependencies {
+    api(projects.graphqlKotlinServer)
+    api(projects.graphqlKotlinFederation)
+    api(libs.ktor.serialization.jackson)
+    api(libs.ktor.server.core)
+    api(libs.ktor.server.content)
+    testImplementation(libs.kotlinx.coroutines.test)
+    testImplementation(libs.ktor.client.content)
+    testImplementation(libs.ktor.server.cio)
+    testImplementation(libs.ktor.server.test.host)
+}
+
+tasks {
+    jacocoTestCoverageVerification {
+        violationRules {
+            rule {
+                limit {
+                    counter = "INSTRUCTION"
+                    value = "COVEREDRATIO"
+                    minimum = "0.65".toBigDecimal()
+                }
+                limit {
+                    counter = "BRANCH"
+                    value = "COVEREDRATIO"
+                    minimum = "0.45".toBigDecimal()
+                }
+            }
+        }
+    }
+}