Try Out Visual Studio Code Development Containers: Kotlin

Ideas are based on the official VS Code Remote Try Java Project

The docker image is based on the ideas from the VS Code java project, but I wanted to try gradle instead. It also uses JDK version 12.

SDKMAN! is used to install kotlin in the container, inspiration for this is from the docker-sdkman project.

This is a sample project that lets you try out the VS Code Remote - Containers extension in a few easy steps.

Challenges

SDKMAN! comes with a sdkman-init.sh script that sets up the environment for the packages installed by SDKMAN! The file has to be sourced in the current /bin/bash which runs inside VS Code. I expected several options to work:

1. Use the CMD directive in the Dockerfile. This is the command that gets executed when the container started. Didn't work...
2. In devcontainer.json you find the option postCreateCommand where I put the source command. Didn't work either
3. I echoed the source command into .bashrc file in the vscode users home. Feels kinda hacky, but maybe you have a better idea. PRs are happily accepted.

Setting up the development container

Follow these steps to open this sample in a container:

1. If this is your first time using a development container, please follow the getting started steps.

2. Linux users: You can update USER_UID and USER_GID in .devcontainer/Dockerfile with your user UID/GID to avoid creating files as root.

3. If you're not yet in a development container:

   • Clone this repository.
   • Press F1 and select the Remote-Containers: Open Folder in Container... command.
   • Select the cloned copy of this folder, wait for the container to start, and try things out!

First steps

Examples are from Venkat Subramaniam Programming Kotlin book.

Open the firststeps folder and run kotlinc-jvm Hello.kt -d Hello.jar and build a JAVA jar file that you can run with java -jar Hello.jar, call the class directly as in java -classpath Hello.jar HelloKt or use the kotlin tool instead: kotlin -classpath Hello.jar HelloKt

Scripting

Runnable kotlin scripts. Files are executable, using the shebang facilities. Alternatively run with: kotlinc-jvm -script script.kts

If all else fails: I put the alias kts into the vscode users .bashrc file so that you can simply execute any script with kts script.kts.