General

Simple example application to explore the Kotlin programming language.

This project is set up as Gradle multi-project build, consisting of two subprojects:

• app: The actual application
• lib: Common utilities and functions used by the application

Application

Starts a simple HTTP server providing following endpoints:

• GET /actuator/health - Returns OK
• GET /actuator/info - Returns some infos like version, commit, JVM version, etc.
• POST /actuator/gc - Run GC
• POST /actuator/shutdown - Shutdown application

Library

The code was written for educational purposes. Don't expect full-flegded production-ready implementations.

Provides basic building blocks for applications, including

• Logging
• Loading HOCON, YAML and property files from classpath
• Dependency injection
• Profiles
• Event bus
• Task scheduling
• NIO HTTP server
• Development mode

Profiles

Profiles can be used to control the behaviour of the application in different environments. The active profile is read from the environment variable BNB1_PROFILE. If not set, 'default' is used.

gradle run activates the profile 'dev'.

Development mode

Development mode watches the source directory for changes and stops the application if a file is modified, added or deleted. This is intended to be used with gradle run -t to trigger compilation and restart on code changes.

Testing

Following libraries are used:

• Kotest (Link)
• MockK (Link)

Build

The build process is configured using Gradle Kotlin DSL.

Used Gradle plugins

• Versions: Checks for dependency updates (Link))
• Dokka: Creates KDoc documentation (Link)
• Shadow: Creates Fat Jar (Link)
• Jib: Containerizes app (Link)
• Test Logger: Prints test logs to console (Link)
• kotlinx.benchmark: Runs JMH benchmarks (Link)
• Ktlint Gradle: Runs ktlint (Link)

Custom extensions

• There is a file 'project.properties' in the root direcotry, which is used for build configuration
• Building the project creates a file 'build.properties', with information like timestamp, commit, ...

Useful Gradle tasks

• List all tasks: ./gradlew tasks
• Clean: ./gradlew clean
• Check for dependency updates: ./gradlew dependencyUpdates
• Run application: ./gradlew run
• Continuous run: ./gradlew run -t
• Run ktlint: ./gradlew ktlintCheck
• Run detekt: ./gradlew detekt
• Run tests: ./gradlew test
• Run benchmarks: ./gradlew benchmark
• Build project and create JAR: ./gradlew build
• Build Docker image: ./gradlew jibDockerBuild
• Build documentation: ./gradlew dokkaHtml
• Update Gradle wrapper: ./gradlew wrapper --gradle-version=X.Y.Z