Ktor Arrow Real World Example

While most "todo" demos provide an excellent cursory glance at a framework's capabilities, they typically don't convey the knowledge & perspective required to actually build real applications with it.

Read the full blog post announcing RealWorld on Medium.

Over 100 implementations have been created using various languages, libraries, and frameworks.

Explore them on CodebaseShow.

In order for Real World back-end and front-end examples to be able to work together we need to follow a predefined openapi.yml.

Looking to contribute?

If you're looking to contribute check-out CONTRIBUTING.MD. Also, this project participates in hacktoberfest!

I will provide personal guidance, and support to everyone that is interested in learning about Ktor, Arrow and Kotlin by contributing to this repository!

How it works

This example uses Kotlin with Ktor and Arrow as the main building blocks. Other technologies used:

• SqlDelight for the persistence layer
• Kotest for testing
• GraalVM to build an optional native binary

Running the project

To run the project, you first need to start the environment. This can be done with docker-compose up, and then you can start the Ktor server with ./gradlew run.

docker-compose up
./gradlew run
curl -i 0.0.0.0:8080/readiness

Beware that ./gradlew run doesn't properly run JVM Shutdown hooks, and the port remains bound.

GraalVM

The project can be built into a native image with GraalVM.

Getting started

1. Ensure a suitable GraalVM is installed
   • Tested versions include:
     • Oracle GraalVM 21+35.1 (project default)
     • Oracle GraalVM 17.0.8
2. Build using ./gradlew nativeCompile
   • An image will be built at /build/nativeCompile/ktor-arrow-sample
3. Start ./gradlew nativeRun (remember to docker-compose up)
   • Verify with curl -i 0.0.0.0:8080/readiness

Known issues

• Ktor uses reflection internally when calling either call.receive() or call.respond()
  • As a workaround, use call.receiveText()/call.respondText() and (de)serialize manually
• nativeTestCompile and nativeTestRun are not supported currently

Troubleshooting & helpful resources

• Configuring GraalVM Gradle buildtool
• Reachability metadata