Executing Gradle builds on Jenkins#
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Building Gradle projects doesn't stop with the developer's machine. Continuous Integration (CI) has been a long-established practice for running a build for every single change committed to version control to tighten the feedback loop.
In this guide, we'll discuss how to configure Jenkins for a typical Gradle project.
What you'll need#
- A text editor
- A command prompt
- The Java Development Kit (JDK), version 1.7 or higher
- A Jenkins installation (setup steps explained in this post)
Setup a typical project#
As an example, this guide is going to focus on a Java-based project. More specifically, a Gradle plugin written in Java and tested with Spek. First, we'll get the project set up on your local machine before covering the same steps on CI.
Just follow these steps:
Clone the Gradle Site Plugin repository#
$ git clone https://github.com/gradle/gradle-site-plugin.git
Cloning into 'gradle-site-plugin'...
$ cd gradle-site-plugin
Build the project#
As a developer of a Java project, you'll typically want to compile the source code, run the tests, and assemble the JAR artifact. That's no different for Gradle plugins. The following command achieves exactly that:
The project provides the Gradle Wrapper as part of the repository. It is a recommended practice for any Gradle project as it enables your project to be built on CI without having to install the Gradle runtime.
Build scan integration#
The sample project is equipped with support for generating build scans. Running the build with the command line option --scan renders a link in the console.
The following section will describe how to build the project with the help of Jenkins.
Setup Jenkins#
Jenkins is one of the most prominent players in the field. In the course of this section, you'll learn how to set up Jenkins, configure a job to pull the source code from GitHub, and run the Gradle build.
Install and start Jenkins#
On the Jenkins website, you can pick from a variety of distributions. This post uses the runnable WAR file. A simple Java command brings up the Jenkins server.
In the browser, navigate to localhost with port 8080 to render the Jenkins dashboard. You will be asked to set up a new administration user and which plugins to install.
Installation of plugins#
Confirm to install the recommended plugins when starting Jenkins for the first time. Under "Manage Jenkins > Manage Plugins," ensure that you have the following two plugins installed:
Next, we can set up the job for building the project.
Create a Jenkins job#
Setting up a new Gradle job can be achieved with just a couple of clicks. From the left navigation bar, select "New Item > Freestyle project". Enter a new name for the project. We'll pick "gradle-site-plugin" for the project.
Select the radio button "Git" in the section "Source Code Management". Enter the URL of the GitHub repository: https://github.com/gradle/gradle-site-plugin.git.
Furthermore, create a "Build step" in the section "Build" by selecting "Invoke Gradle script". As mentioned before, we'll want to use the Wrapper to execute the build. In the "Tasks" input box, enter build and use the "Switches" --scan -s to generate a build scan and render a stack trace in case of a build failure.
Execute the job#
Save the configuration of the job and execute an initial build by triggering the "Build Now" button. The build should finish successfully and render a "Gradle Build Scan" icon that brings you directly to the build scan for the given build.
There are various options to trigger Jenkins builds continuously: from polling the repository periodically, to building on a set schedule, or via callback URL.
Further reading#
You can learn more about advanced Jenkins usage through these resources:
- Using credentials with Jenkins
- Pipeline as code with Jenkins
- Modeling a Continuous Deployment pipeline for a Spring Boot application
Summary#
Executing Gradle builds on CI can be set up and configured with just a handful of steps. The benefit of receiving fast feedback clearly speaks for itself. If you are not using Jenkins, no problem, many CI products tightly integrate with Gradle as a first-class citizen.