Apache Sling Starter

This module is part of the Apache Sling project.

The starter project produces feature artifacts that can be launched using the Feature Launcher.

It is not meant to be a production-ready setup, more as a way to facilitate experimenting and learning Sling.

See Releasing a new version of the Sling starter for how to create a release of this module.

How to run the Sling Starter module in Standalone mode

Note This is a note “mvn clean” deletes the “launcher” work directory in the project base directory. It is advisable to use a work directory outside of the project directory.

1. Build the Sling Starter using

   mvn clean install
   

   in the current directory.

   Hint You can defer stopping the instance after running the ITs with argument -Dfeature-launcher.waitForInput=true to do some manual checks.

2. Start Sling backed by

   • Oak SegmentStore with

     target/dependency/org.apache.sling.feature.launcher/bin/launcher -f target/slingfeature-tmp/feature-oak_tar.json
     

     If you are using Windows:

     target\dependency\org.apache.sling.feature.launcher\bin\launcher.bat -f target\slingfeature-tmp\feature-oak_tar.json
     

   • Oak MongoDB DocumentStore with

     target/dependency/org.apache.sling.feature.launcher/bin/launcher -f target/slingfeature-tmp/feature-oak_mongo.json
     

     If you are using Windows:

     target\dependency\org.apache.sling.feature.launcher\bin\launcher.bat -f target\slingfeature-tmp\feature-oak_mongo.json
     

     This expects a MongoDB server to be running, search for mongodb:// in the feature files for the expected URL (currently mongodb://localhost:27017).

3. Browse Sling in localhost:8080

How to run the Sling Starter Docker image

The following tags are supported

1. Start Sling Docker image backed by
   • Oak SegmentStore with

     docker volume create sling-launcher
     docker run --rm -p 8080:8080 -v sling-launcher:/opt/sling/launcher apache/sling:snapshot
     

   • Oak MongoDB DocumentStore with

     docker volume create sling-launcher
     docker run --rm -p 27017:27017 mongo:4.4.6
     docker run --rm -p 8081:8080 -v sling-launcher:/opt/sling/launcher apache/sling:snapshot oak_mongo
     

The docker/ directory contains sample files related to container-based development.

Testing

The Sling Starter will execute two suites of tests using the maven-surefire-plugin:

1. A small set of smoke tests, embedded in the project, that verify the basic functionality of the Starter
2. An extensive set of end-to-end tests that verify the overall functionality of the Starter and the bundles that are embedded into it

By default, these are both executed when building the project against an Oak SegmentNodeStore backend.

Additionally, when the ci profile is enabled the smoke tests are also executed in against an Oak DocumentNodeStore backend. For technical resons, the full end-to-end tests are not executed.

Docker

The Sling Starter Docker image is only for testing/learning purposes. For your custom applications, please configure your Feature model and build your image with all dependencies and configurations built in.

Our example Docker image uses /opt/sling/bin/launch.sh script as the entrypoint. It supports the following environment variables:

The following command arguments are supported:

[!NOTE]
The --extra-features argument is intended for quick experiments and debugging. When using the this functionality there is no guarantee that the features are compatible with the Sling Starter configuration and startup will proceed even if some bundles cannot resolve. It is recommended to build a custom image with the required features and to run the appropriate feature model analysers during the build.

Example running Sling Starter in debug mode with custom memory settings

docker run -p 8080:8080 -p 5005:5005 -e JAVA_DEBUG_PORT=5005 -e EXTRA_JAVA_OPTS='-Xms256m -Xmx2048m' apache/sling:snapshot

running Sling Starter with an additional feature available in the default repositories

docker run -p 8080:8080 apache/sling:snapshot oak_tar --extra-features mvn:org.apache.sling/org.apache.sling.thumbnails/1.0.2/slingosgifeature/default

running Sling Starter with a SNAPSHOT feature available in the local Maven repository

docker run -p 8080:8080 -v $HOME/.m2/repository:/opt/sling/m2repo apache/sling:snapshot oak_tar --repository-urls file:///opt/sling/m2repo https://repo.maven.apache.org/maven2  --extra-features mvn:org.apache.sling/org.apache.sling.thumbnails/1.0.3-SNAPSHOT/slingosgifeature/default

Building the Docker image

This module can optionally build a Docker image. This is achieved by running a build with the -Ddocker.skip=false argument. By default, the image is built as apache/sling:snapshot. The tag can be overrriden using the docker.image.tag Maven property.

$ mvn clean package -Ddocker.skip=false -Ddocker.image.tag=local
$ docker run --rm -p 8080:8080 apache/sling:local

Extending the Sling Starter

If you wish the extend the Sling Starter but would like to keep various application-level features out, you can start with the nosample_base aggregate, which contains:

• all the base features
• Oak base features, without the NodeStore setup
• No applications ( Composum, Slingshot, etc )

For instance, launching an empty Sling Starter with segment persistence can be achieved by running

target/dependency/org.apache.sling.feature.launcher/bin/launcher -f target/slingfeature-tmp/feature-nosample_base.json,target/slingfeature-tmp/feature-oak_persistence_sns.json

Your own feature files can be added to the feature list.

Helper scripts

The scripts directory contains helper scripts that will aid with local development by simplifying the use of tools external to the Sling Starter.