Ktor GraalVM Server Example

This repository contains an example project to build a ktor jvm server with GraalVM native-image.

Features

• JSON Rest API (/api/v1/news)
• Exposed DB persistence
• H2 in-memory database
• Micrometer + Prometheus monitoring
• Automatic error handling
• CallID plugin
• Custom Logging Middleware (Ktor Application Plugin)

Required

• Linux/MacOS
• GraalVM installed and set as environment variable JAVA_HOME (sdkman easiest variant)
• native-image installed (use gu) and reachable

Build & Run native image

• Directly run with ./gradlew nativeRun
• Compile
  • ./gradlew nativeCompile
  • Run with ./graal-server
• Use option --native-quick-build or evironment variable GRAALVM_QUICK_BUILD=true for faster builds

Docker Image (not tested!)

• Use Dockerfile for multistage native-image build.
• Results image is minmal size based of scratch

Known Issues

• Micrometer not working correct on native
• Serialization is not working for native-image out of the box
  • Follow this GitHub Issue for progress
  • Somewhat workaround: Analyze reflection by running Jar with tracing mode
    • Run with tracing ./gradlew -Pagent run
      • Try to test all possible paths (also possible via running tests)
    • Copy tracing config ./gradlew metadataCopy --task run --dir src/main/resources/META-INF/native-image