How to run a Kotlin script on GitHub Actions?

Running Kotlin scripts on GitHub Actions is a valuable technique, especially when integrating Kotlin code into automated build and test pipelines. Below, I will outline the steps to configure and run Kotlin scripts on GitHub Actions.

Step 1: Prepare Kotlin Scripts

First, ensure your project includes one or more Kotlin scripts. For example, assume a simple Kotlin script located in the scripts directory named hello.kts, with the following content:

kotlin
println("Hello from Kotlin script!")

Step 2: Set Up GitHub Repository

Ensure your Kotlin scripts have been pushed to the GitHub repository. If you don't have a repository, create a new one on GitHub and push your project code to it.

Step 3: Create GitHub Actions Workflow File

In your GitHub repository, create a .github/workflows directory (if it doesn't exist) and create a new YAML file within it, such as run-kotlin.yml. This file will define the GitHub Actions workflow.

Step 4: Configure the Workflow

In the run-kotlin.yml file, define a workflow to install the Kotlin environment and run the Kotlin script. Here is a basic configuration example:

yaml
name: Run Kotlin Script

on: [push]

jobs:
  run-script:
    runs-on: ubuntu-latest

    steps:
    - uses: actions/checkout@v2
      name: Check out repository

    - name: Set up JDK 11
      uses: actions/setup-java@v1
      with:
        java-version: '11'  # Set JDK version

    - name: Run Kotlin script
      run: |
        curl -s https://get.sdkman.io | bash
        source "$HOME/.sdkman/bin/sdkman-init.sh"
        sdk install kotlin
        kotlinc -script scripts/hello.kts  # Run Kotlin script

Explanation

1. Trigger Condition: This workflow triggers when code is pushed to the repository.
2. Workflow Job: Defines a job named run-script that runs in the latest Ubuntu virtual environment provided by GitHub.
3. Steps:
   • Checkout Code: actions/checkout@v2 is used to check out the GitHub repository code into the virtual environment where the workflow runs.
   • Set up JDK: Since Kotlin is Java-based, a Java environment is required. Here, actions/setup-java@v1 is used to install JDK 11.
   • Run Kotlin Script: First, use curl to download and install SDKMAN, then use SDKMAN to install the Kotlin compiler and runtime environment. Finally, execute the Kotlin script using the kotlinc -script command.

Step 5: Commit and Push Changes

Commit and push the run-kotlin.yml file to your GitHub repository. GitHub will automatically detect YAML files in the .github/workflows directory and execute the defined workflow when the trigger condition is met.

With the above steps, you can successfully run Kotlin scripts on GitHub Actions. This automated approach is well-suited for continuous integration and continuous deployment scenarios.