Deploying Sling CMS Apps with GitHub Actions

I use Apache Sling CMS for my personal site, so I can easily author my blog posts from nearly anywhere. Unfortunately, since this is a personal site, I'm not exactly spending the dollars on building out a full Continuous Integration / Delivery process. 

Enter GitHub Actions

GitHub provides Actions, a free for limited use solution for executing code on Git repository events. With GitHub Actions, I can set up a pipeline to automatically deploy my code on changes to the master branch.

Actions Pipeline Definition

The pipeline is defined as a YAML file, deploy.yaml, under the directory .github.workflows in my code repository.

# Deploys code updates to my personal site on push to the master branch

name: Deploy on Push
on:
  push:
    branches:
      - master
jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v2
    - name: Set up JDK 1.8
      uses: actions/setup-java@v1
      with:
        java-version: 1.8
        server-id: github
        settings-path: ${{ github.workspace }}
    - name: Build and Deploy
      run: mvn install -B -s $GITHUB_WORKSPACE/settings.xml -PautoInstallBundle,ci
      env:
        SLING_HOST: ${{ secrets.DEPLOY_HOST }}
        SLING_USERNAME: ${{ secrets.DEPLOY_USERNAME }}
        SLING_PASSWORD: ${{ secrets.DEPLOY_PASSWORD }}
        SLING_PROTOCOL: https
        SLING_PORT: 443

A few things to note about the pipeline definition:

• The definition on object contains my invocation definition, in this case, pushes to master
• In the Maven command, I've added a custom profile ci, this profile will copy the environment variables seen in the env object
• The env parameter to Build and Deploy contains the parameters, including secret parameters for deploying the code

Keeping Secrets, Secret

In order to deploy my code, I have to provide the CMS authoring URL and the username / password for an Administrative user. Naturally, I don't want to put this information on the web. With GitHub Actions, I can create secrets within the project: 

And then use the ci profile in the POM to copy those secrets as environment variables from the env parameter in the Github Actions pipeline into the Maven project properties.

<profile>
    <id>ci</id>
    <properties>
        <sling.host>${env.SLING_HOST}</sling.host>
        <sling.port>${env.SLING_PORT}</sling.port>
        <sling.username>${env.SLING_USERNAME}</sling.username>
        <sling.password>${env.SLING_PASSWORD}</sling.password>
        <sling.protocol>${env.SLING_PROTOCOL}</sling.protocol>
    </properties>
</profile>

Once this is all wired up, you can push in a small change to execute the pipeline and you should see the deployment succeed. Note that the secrets are hidden from the logs so even if a user can see the pipeline, they cannot see the secret values.

With Github Actions, you can not only host a small Apache Sling CMS website for free, but you can even have a reliable CI/CD process!