Ktor Server GraphQL

About

Ktor Server GraphQL is a ktor plugin built on top of graphql-kotlin. The plugin is meant to ease the configuration of kotlin-graphql-server within a ktor project and includes the necessary libraries as dependencies.

Installation

Add the following dependency to your build.gradle.kts:

implementation("com.bscharm:ktor-server-graphql:2.0.0")

Usage

The plugin can be installed like any other ktor (2.0 +) plugin. Here installation is shown using ktor's embedded server syntax:

embeddedServer(Netty, port = 8080) {
    install(GraphQL) {
        queries = listOf(SomeQuery(), SomeOtherQuery())
        mutations = listOf(SomeMutation())
        packages = listOf("my.schema.package")
    }
}.start(wait = true)

Dependencies

As the underlying framework, graphql-java, relies on jackson for serialization, so too does this plugin. If you do not have the ContentNegotiation plugin installed it will be installed for you but scoped to the route for GraphQL. If you install on your own, be sure to use jackson as the serializer.

Configuration

Property	Type	Default Value	Description
queries	List<Query>	emptyList()	List of top level queries for your GraphQL schema. Each must meet the Query interface
mutations	List<Mutation>	emptyList()	List of top level mutations for your GraphQL schema. Each must meet the Mutation interface
subscriptions	List<Subscription>	emptyList()	List of top level subscriptions for your GraphQL schema. Each must meet the Subscription interface
packages	List<String>	emptyList()	List of packages where non-primitive types which are referenced in your schema (Queries or Mutations) are located. The schema will fail on app startup if misconfigured
hooks	SchemaGeneratorHooks	NoopSchemaGeneratorHooks	Custom SchemaGeneratorHooks used to support types beyond the supported primitives. See the documentation for more details. An example to support UUID is also given.
contextFactory	ContextFactoryFunction	NoopContextFactoryFunction	Custom ContextFactoryFunction used to build up the context map for each request. This function takes the ApplicationRequest and returns a map which can be consumed by resolvers. See the documentation for details and examples.
playground	Boolean	false	If enabled, will include the GraphQL Playground mounted at playgroundPath
authentication	Boolean	false	If enabled, will attempt to find the ktor auth plugin configuration using authenticationName (optional)
authenticationName	String?	null	Use a specific named auth configuration. If left null, will use the any unnamed auth configuration. See ktor docs for more details on auth configuration
path	String	"graphql"	Path where the GraphQL executor will be mounted
subscriptionsPath	String	"subscriptions"	Path where the GraphQL subscription websocket executor will be mounted
playgroundPath	String	"playground"	Path where the playground will be mounted if enabled

Examples

Authentication

embeddedServer(Netty, port = 8080) {
    install(Authentication) {
        basic("custom-auth-name") {
            validate {
                if (it.name == "foo" && it.password == "bar") {
                    UserIdPrincipal("foo")
                } else {
                    null
                }
            }
        }
    }

    install(GraphQL) {
        queries = listOf(SomeQuery(), SomeOtherQuery())
        mutations = listOf(SomeMutation())
        packages = listOf("my.schema.package")
        authentication = true
        authenticationName = "custom-auth-name" // this can be omitted if omitted above
    }
}.start(wait = true)

ContextFactory

embeddedServer(Netty, port = 8080) {
    val factoryFunction: ContextFactoryFunction = { request: ApplicationRequest ->
        // insert value from custom header into the map
        return request.headers.get("X-CUSTOM-HEADER")?.let { mapOf("customHeader" to it) } ?: emptyMap()
    }

    install(GraphQL) {
        queries = listOf(SomeQuery(), SomeOtherQuery())
        mutations = listOf(SomeMutation())
        packages = listOf("my.schema.package")
        authentication = true
        authenticationName = "custom-auth-name" // this can be omitted if omitted above
        contextFactory = factoryFunction
    }
}.start(wait = true)

Development

While the project is configured as kotlin multiplatform, currently only the JVM target is supported.

Tests

To run tests:

./gradlew jvmTest

You can also run the following to compile as well as run tests:

./gradlew check

Local Installation

To install the plugin to your local maven repository for testing, the maven-publish plugin is installed.

./gradlew publishToMavenLocal