Building with Gradle

Relevant source files

The following files were used as context for generating this wiki page:

• complete/gradlew
• complete/gradlew.bat
• initial/gradlew.bat
• test/run.sh
• README.adoc
• complete/manifest.yml

This document provides a technical overview of the Gradle build system as configured in the gs-rest-service project. The project utilizes the Gradle Wrapper, which ensures a consistent and reproducible build environment by using a specific version of Gradle without requiring a manual installation. This allows developers to compile, test, and package the application using simple commands.

The build process is initiated via the gradlew (for Unix-like systems) or gradlew.bat (for Windows) scripts. These scripts handle the setup of the Java environment and execute the Gradle Wrapper Java application, which in turn performs the build tasks. The primary output of the build is an executable JAR file.

Sources: README.adoc:28-30, complete/gradlew.bat, test/run.sh:26

Gradle Wrapper Scripts

The project includes wrapper scripts for both Windows (gradlew.bat) and Unix-like (gradlew) operating systems. These scripts are the entry points for all Gradle tasks.

Sources: complete/gradlew, complete/gradlew.bat, initial/gradlew.bat

Script Execution Flow

The wrapper scripts perform several key steps before executing Gradle:

1. Environment Setup: The script sets up its home directory (APP_HOME).
2. Java Virtual Machine (JVM) Configuration: It defines default JVM options, such as memory allocation (-Xmx64m, -Xms64m). These can be overridden by JAVA_OPTS or GRADLE_OPTS environment variables.
3. Java Executable Discovery: The script searches for a Java executable. It first checks if the JAVA_HOME environment variable is set and valid. If not, it attempts to use the java command from the system's PATH.
4. Gradle Wrapper Execution: Once Java is found, the script executes the gradle-wrapper.jar file, passing along any command-line arguments. The main class executed is org.gradle.wrapper.GradleWrapperMain.

Sources: complete/gradlew.bat:26-60, initial/gradlew.bat:26-60

The following diagram illustrates the execution flow of the gradlew.bat script.

Environment Variables

The wrapper scripts can be configured using several environment variables.

Variable	Description	Source File
JAVA_HOME	Specifies the location of the JDK installation. If not set, the script searches for java in the system's PATH.	complete/gradlew.bat:31-32
JAVA_OPTS	Used to pass additional JVM options to the Gradle process.	complete/gradlew.bat:60
GRADLE_OPTS	Also used to pass JVM options to the Gradle process.	complete/gradlew.bat:60
DEBUG	If set, script execution commands are echoed to the console.	initial/gradlew.bat:20

Build and Test Lifecycle

The project's build lifecycle is managed through Gradle tasks. The test automation script test/run.sh demonstrates the primary commands used for building and cleaning the project.

Sources: test/run.sh, README.adoc

Key Gradle Tasks

• ./gradlew build: This is the main command to build the project. It compiles the source code, runs tests, and packages the application into an executable JAR file. The test/run.sh script executes this command on the complete version of the project.
• ./gradlew compileJava: This task, used in test/run.sh on the initial project, compiles the Java source files without running tests or packaging the application.
• ./gradlew clean: While not explicitly shown as a command, the test/run.sh script simulates a clean by manually removing the build directory (rm -rf build), which is the standard output directory for Gradle builds.

Sources: test/run.sh:10,13,26,32, README.adoc:103

The following sequence diagram shows the interaction when a developer runs the build command.

Build Artifacts

The primary output of the build task is a JAR file located in the build/libs directory. The complete/manifest.yml file, used for deployment, specifies the exact path to this artifact.

• Artifact Path: build/libs/gs-rest-service-0.1.0.jar

This JAR is an executable "fat jar" containing all necessary dependencies to run the Spring Boot application.

Sources: complete/manifest.yml:7, test/run.sh:10,32

The build process can be summarized as taking source files and producing a runnable application.

Summary

The gs-rest-service project relies on the Gradle Wrapper for a standardized and portable build system. By using the gradlew and gradlew.bat scripts, developers can easily compile, test, and package the REST service into an executable JAR. The process is self-contained, only requiring a JDK to be available on the host system, which simplifies the development and continuous integration workflow.

Sources: complete/gradlew.bat, README.adoc