Gradle + Scala Development Project Base

This is a simple development project base you can build upon and customize to jumpstart a new Gradle + Scala project, instead of starting from scratch. The template provides a skeleton with a range of options from which you can choose to keep only those relevant for your project.

Content Overview

The project base includes:

• template HOCON config file
• config file loading based on filepath from input args using PureConfig magic
• template log4J setup
• ScalaTest
• Gradle shadowJar (fatJAR) building with commit hash recorded in its Manifest
• Gradle TAR distribution packaging the fatJAR with additional resources and the configuration file
• Gradle template setup for docker image building (just the Gradle side of things, no Dockerfile)
• a template bash script to fill in with any pre-processing you need and trigger the JAR (if Docker is being used, this can be your Docker entrypoint)
• a base for keeping multiple configuration files and dynamically loading the correct one based on env build property

Prerequisites

• git

Setup

1. Use GitHub's Use this template feature to start your own repository with this structure or run git clone https://github.com/holuond/gradle_scala_dev_project_base.
2. In your IDE, create a new project from existing sources (select the build.gradle file).
3. Run gradlew clean build --info to build the project.
4. (Recommended) Replace all placeholder values. Search for all occurrences of your.app, your.pckg and your.repo and replace them with your custom values based on the context. Also replace your/package in the path under src/main/your/package and src/test/your/package and rename the root project directory.
5. (Optional) If you require a different Gradle version then provided via the wrapper, run gradle wrapper if you have a local Gradle installation or use gradlew wrapper --gradle-version <version>.

Usage Examples

1. You can choose to only use the part of the setup that outputs a distribution archive containing a HOCON config file, logging configuration and a fatJar and remove the Docker setup from build.gradle. Then, you can run the following to build and package the distribution tar archive:

   gradlew clean distTar --info

   And then you simply unpack the distribution and run the jar:

   dist_dir='your/project/build/distributions'
   artifact_name='example-0.0.1-SNAPSHOT'
   dist="$dist_dir/$artifact_name"
   
   if [ ! -d $dist ]; then
       tar -xf $dist.tar --directory $dist_dir
   fi
   $dist/bin/run.sh -j $dist/lib/$artifact_name-all.jar -c $dist/conf/application.conf -l $dist/conf/log4j.xml

2. Or you can wrap the output distribution archive in a Docker image. In that case, you can use the prepared docker task in the build.gradle file and connect it and its build arguments to your Dockerfile (where you can consume the ARGs from the docker task). You can leverage run.sh as your Docker entrypoint.